@article{angle_lechner_reece_stevie_kelley_2023, title={Analysis of furnace contamination on superconducting radio frequency niobium using secondary-ion mass spectrometry}, volume={41}, ISSN={["2166-2754"]}, DOI={10.1116/6.0002624}, abstractNote={Detection of surface contamination on niobium materials used in superconducting radio frequency (SRF) applications is difficult due to quantitative sensitivity and near-atomic depth resolution needed. Inspection of samples known to have experienced surface contamination was found to have inconsistent nitride coverage after high-temperature nitrogen gas exposure (“doping”). We compare contaminating species found on samples treated in several different vacuum furnaces, both “exposed” directly in the chamber and “protected” by containment shielding from evaporative sources with “furnace caps.” Typically, furnace caps are used to impede contamination from reaching the interior surface of cavities during the high-temperature vacuum bake that immediately precedes exposure to nitrogen gas. Although, to date, little is known about the effectiveness of these caps, SIMS results showed that they were effective in limiting contamination arising from the furnace environment. Inspection of sample surfaces by SEM showed a lack of nitrides present on contaminated specimens. TEM with energy dispersive spectroscopy performed on these samples revealed that a carbon-rich layer now existed, indicating that a relatively high contaminant load prevents the nucleation and growth of surface nitrides, while thus inhibiting interstitial nitrogen uptake. Except in extreme cases, subsequent removal of the top several micrometers of the surface via electropolishing appears to effectively eliminate any strong influence on the subsequent SRF cavity performance. With the absence of furnace cleaning, carbon contamination was found to be nearly 10× higher for protected nitrogen-doped and electropolished samples, with minimal metallic contamination detected for both processes. SIMS analysis was also performed to compare the cleanliness of samples fully prepared by such nitrogen “doping” with those prepared by a related process, involving the dissolution of niobium surface oxide and diffusion of oxygen into the surface. This oxygen doping or alloying process offers attractive advantages.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Angle, Jonathan W. and Lechner, Eric M. and Reece, Charles E. and Stevie, Fred A. and Kelley, Michael J.}, year={2023}, month={May} }
 @article{garcia_giannuzzi_stevie_strader_2022, title={Enhanced focused ion beam milling with use of nested raster patterns}, volume={40}, ISSN={["2166-2754"]}, DOI={10.1116/6.0001411}, abstractNote={The focused ion beam (FIB) instrument is designed to provide the removal of material with nanometer-scale precision. However, one often needs to remove a substantial amount of material to expose the region of interest or prepare a specimen for transmission electron microscopy analysis. The maximum current available on Ga+ FIB sources is less than 100 nA, and this is a limiting factor when removal on the millimeter scale is desired. Any improvement in the removal rate reduces the analysis time and increases the range of samples that can be analyzed. Optimization of ion beam parameters, such as dwell time and overlap, can improve material removal and reduce redeposition. Since sputtering occurs faster at an edge, the use of a nested arrangement of raster patterns to more frequently present an edge to the ion beam was able to improve the removal of material at the region of interest by over 30% in the silicon and polycrystalline copper substrates used for this study. A confocal laser scanning microscope made possible an accurate determination of the material removed.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Garcia, Roberto and Giannuzzi, Lucille A. and Stevie, Fred A. and Strader, Phillip}, year={2022}, month={Jan} }
 @article{angle_lechner_palczewski_reece_stevie_kelley_2022, title={Improved quantitation of SIMS depth profile measurements of niobium via sample holder design improvements and characterization of grain orientation effects}, volume={40}, ISSN={["2166-2754"]}, DOI={10.1116/6.0001741}, abstractNote={The importance of SIMS analyses for “N-doped” impurity alloyed niobium and other surface-alloyed materials continues to increase. A major hurdle is the uncertainty of instrument calibration due to changes in sample height either from sample surface topography or from the sample holder itself. The CAMECA sample holder design allows for many types of samples to be analyzed. However, a drawback is that the holder faceplate can bend, contributing an uncertainty in the relative sensitivity factor (RSF) used to quantify the SIMS results. Here, we describe an improved sample holder having a reinforced faceplate, which prevents deflection and reduces uncertainty. Simulations show that the new design significantly reduces deflection from 10  μm to 5 nm. Sample measurements show a reduction of RSF uncertainty from this source from 4.1% to 0.95%. Grain orientation has long been suspected to affect RSF measurement as well. A bicrystal implant standard, consisting of randomly oriented and [001] grains, was successively rotated 15° between analyses. It was observed that 20% of the analyses performed on the randomly oriented grain exhibited anomalously high RSF values as well as slow sputter rates. These features were associated with the changing grain normal orientation with respect to the primary Cs+ beam. The grain orientation associated with the rise in RSF was simulated and determined to be the [101] crystallographic plane, thus indicating that ion channeling was responsible for the significantly increased RSF. Focused ion beam analysis confirmed slower sputter rates for the cardinal crystallographic orientations, indicating that ion channeling occurred for each.}, number={2}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Angle, Jonathan W. and Lechner, Eric M. and Palczewski, Ari D. and Reece, Charles E. and Stevie, Fred A. and Kelley, Michael J.}, year={2022}, month={Mar} }
 @article{ramaswamy_devkota_pokharel_nalamati_stevie_jones_reynolds_iyer_2021, title={A study of dopant incorporation in Te-doped GaAsSb nanowires using a combination of XPS/UPS, and C-AFM/SKPM}, volume={11}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-021-87825-4}, abstractNote={Abstract We report the first study on doping assessment in Te-doped GaAsSb nanowires (NWs) with variation in Gallium Telluride (GaTe) cell temperature, using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), conductive-atomic force microscopy (C-AFM), and scanning Kelvin probe microscopy (SKPM). The NWs were grown using Ga-assisted molecular beam epitaxy with a GaTe captive source as the dopant cell. Te-incorporation in the NWs was associated with a positive shift in the binding energy of the 3d shells of the core constituent elements in doped NWs in the XPS spectra, a lowering of the work function in doped NWs relative to undoped ones from UPS spectra, a significantly higher photoresponse in C-AFM and an increase in surface potential of doped NWs observed in SKPM relative to undoped ones. The carrier concentration of Te-doped GaAsSb NWs determined from UPS spectra are found to be consistent with the values obtained from simulated I–V characteristics. Thus, these surface analytical tools, XPS/UPS and C-AFM/SKPM, that do not require any sample preparation are found to be powerful characterization techniques to analyze the dopant incorporation and carrier density in homogeneously doped NWs.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Ramaswamy, Priyanka and Devkota, Shisir and Pokharel, Rabin and Nalamati, Surya and Stevie, Fred and Jones, Keith and Reynolds, Lew and Iyer, Shanthi}, year={2021}, month={Apr} }
 @article{angle_palczewski_reece_stevie_kelley_2021, title={Advances in secondary ion mass spectrometry for N-doped niobium}, volume={39}, ISSN={["2166-2754"]}, DOI={10.1116/6.0000848}, abstractNote={Accurate secondary ion mass spectroscopy measurement of nitrogen in niobium relies on the use of closely equivalent standards, made by ion implantation, to convert nitrogen signal intensity to nitrogen content by determination of relative sensitivity factors (RSFs). Accurate RSF values for ppm-range nitrogen contents are increasingly critical, as more precision is sought in processes for next-generation superconducting radiofrequency (SRF) accelerator cavities. Factors influencing RSF value measurements were investigated with the aim of reliably attaining better than 10% accuracy in nitrogen concentrations at various depths into the bulk. This has been accomplished for materials typical of SRF cavities at the cost of increased attention to all aspects.}, number={2}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Angle, Jonathan W. and Palczewski, Ari D. and Reece, Charles E. and Stevie, Fred A. and Kelley, Michael J.}, year={2021}, month={Mar} }
 @article{zhou_stevie_garcia_2020, title={Analysis of permethrin treated fabric using ToF-SIMS}, volume={38}, ISSN={["2166-2746"]}, DOI={10.1116/1.5141467}, abstractNote={Recent studies have shown that it is possible to use ToF-SIMS to identify and quantify mosquito insecticides, such as permethrin and deltamethrin, on mosquito netting. The insecticide in those studies was incorporated in the netting fiber. Permethrin treated fabric is in common usage to provide mosquito repellent clothing and is the only approved insecticide for apparel. The insecticide is applied to the fabric and will no longer be effective after a certain number of washing cycles. ToF-SIMS analyses have now been conducted on fabric composed of nylon and cotton before washing and after 10 and 30 washes to measure the reduction in insecticides. The results show a significant decrease in the insecticide between 10 and 30 washes. The 30 washes sample was known to be no longer effective against mosquitoes. ToF-SIMS was also able to differentiate cotton and nylon fibers. A cross-sectional analysis of cryomicrotomed samples showed the distribution of the insecticide in the individual fibers. The insecticide was found to penetrate completely through the fibers during its application. After ten washes, the insecticide was depleted more rapidly in the cotton than the nylon fibers. The results have implications for the number of acceptable washes for mosquito repellent fabric.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Zhou, Chuanzhen and Stevie, Fred and Garcia, Roberto}, year={2020}, month={May} }
 @article{stevie_donley_2020, title={Introduction to x-ray photoelectron spectroscopy}, volume={38}, ISSN={["1520-8559"]}, DOI={10.1116/6.0000412}, abstractNote={X-ray photoelectron spectroscopy (XPS) has become one of the most widely used surface analysis techniques, and XPS instrumentation has become more user friendly, making the technique available to a large number of researchers. The number of experts in the field, however, has not increased, and XPS data are often misinterpreted in the literature. This paper is intended to provide an introduction to XPS for prospective or novice users. We present the basic principles of the technique including (1) the photoelectric effect, (2) how electrons interact with matter and escape from a surface and how this determines the surface sensitivity of the technique, and (3) how the chemical environment around an element affects the binding energy of its electrons. A description of the instrumentation helps a novice user understand how data are acquired, and information is included on sample preparation and mounting. The important parameters for data acquisition are noted to help guide users starting to acquire data. Interpretation of data on both a qualitative and quantitative level is discussed, and additional sections provide information on more advanced techniques such as angle resolved XPS, small area analysis, near ambient pressure XPS, valence XPS, and ultraviolet photoelectron spectroscopy.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Stevie, Fred A. and Donley, Carrie L.}, year={2020}, month={Dec} }
 @article{stevie_garcia_shallenberger_newman_donley_2020, title={Sample handling, preparation and mounting for XPS and other surface analytical techniques}, volume={38}, ISSN={["1520-8559"]}, DOI={10.1116/6.0000421}, abstractNote={Sample preparation and mounting are important aspects of x-ray photoelectron spectroscopy (XPS) analysis. New users do not know many techniques that are familiar to analysts with years of experience, and these observations and “tricks of the trade” are typically not published. This article is intended to convey the experience of the authors in this field who have creatively analyzed a wide range of samples. Samples can include solids, powders, fibers, porous solids, and even liquids. This information is also important to anyone submitting samples for analysis, since the preparation of the sample may influence the usefulness of the data collected. These techniques are also applicable to other surface analysis methods.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Stevie, Fred A. and Garcia, Roberto and Shallenberger, Jeffrey and Newman, John G. and Donley, Carrie L.}, year={2020}, month={Dec} }
 @article{tuggle_pudasaini_angle_eremeev_reece_stevie_kelley_2019, title={Electron backscatter diffraction of Nb3Sn coated niobium: Revealing structure as a function of depth}, volume={37}, ISSN={["2166-2746"]}, DOI={10.1116/1.5096338}, abstractNote={Over the last two decades, advances in Electron Backscatter Diffraction (EBSD) have moved the technique from a research tool to an essential characterization technique in many fields of material research. EBSD is the best suited technique for determining structure as a function of depth. This characterization is critically important but has been previously absent from Nb3Sn efforts. While EBSD is the technique of choice, obtaining quality data can be difficult. Sample preparation in particular is nontrivial. Here, we summarize the general principles of EBSD, discuss specific sample preparation techniques for Nb3Sn coated SRF cavity materials, and give examples of how EBSD is being used to understand fundamental growth mechanisms for Nb3Sn coatings.Over the last two decades, advances in Electron Backscatter Diffraction (EBSD) have moved the technique from a research tool to an essential characterization technique in many fields of material research. EBSD is the best suited technique for determining structure as a function of depth. This characterization is critically important but has been previously absent from Nb3Sn efforts. While EBSD is the technique of choice, obtaining quality data can be difficult. Sample preparation in particular is nontrivial. Here, we summarize the general principles of EBSD, discuss specific sample preparation techniques for Nb3Sn coated SRF cavity materials, and give examples of how EBSD is being used to understand fundamental growth mechanisms for Nb3Sn coatings.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Tuggle, Jay and Pudasaini, Uttar and Angle, Jonathan and Eremeev, Grigory and Reece, Charlie E. and Stevie, Fred A. and Kelley, Michael J.}, year={2019}, month={Sep} }
 @article{zhou_sun_garcia_stevie_2018, title={Determination of chemical composition in multilayer polymer film using ToF-SIMS}, volume={10}, ISSN={["1759-9679"]}, DOI={10.1039/c8ay00344k}, abstractNote={Time-of-flight secondary ion mass spectrometry is a widely used surface analytical technique, which can provide chemical information from both the uppermost surface and underneath the surface for various materials. For identification of the structure of a multilayer polymer film with unknown chemical composition, it is generally not practical to perform depth profiling using atomic ion sputtering because it will destroy the chemical information and it is difficult to obtain accurate chemical depth distributions. In this study, we present an alternative approach to microtome the polymer film to reveal the multilayer cross-section followed by imaging the cross-section with bismuth liquid metal ion gun (LMIG). To identify the spatial distribution of the thin inorganic layer in the multilayer film, bismuth sputtering was employed on the same analysis area to remove organic mass interference. Overlaid images from two separate analyses allow us to determine both inorganic and organic layers chemically and laterally with high lateral resolution.}, number={21}, journal={ANALYTICAL METHODS}, author={Zhou, Chuanzhen and Sun, Dayong and Garcia, Roberto and Stevie, Fred A.}, year={2018}, month={Jun}, pages={2444–2449} }
 @article{smith_zhou_stevie_garcia_2018, title={Imaging and quantitative analysis of insecticide in mosquito net fibers using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS)}, volume={13}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0209119}, abstractNote={Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis was used to qualitatively and quantitatively assess the distribution of permethrin insecticide on the surfaces and interiors of Olyset long-lasting insecticidal net (LLIN) fibers. Total insecticide content in LLINs has been established using many analytical methods. However, it is important to quantify the bioavailable portion residing on the fiber surfaces for incorporated LLINs. ToF-SIMS is a very surface sensitive technique and can directly image the spatial distribution of permethrin insecticide on the surface of Olyset fibers. Surface permethrin appeared as patchy deposits which were easily removed by acetone and reappeared after several days as interior permethrin migrated (bloomed) from the fiber interior. After a wash/incubation cycle, permethrin deposits were more diffuse and less concentrated than those on the as-received fibers. ToF-SIMS is particularly sensitive to detect the Cl- ion, which is the characteristic ion of permethrin. Ion implantation and quantification of dopants using SIMS is well established in the semiconductor industry. In this study, quantitative depth profiling was carried out using 35Cl- ion implantation to correlate secondary ion yield with permethrin concentration, yielding a limit of detection of 0.051 wt% for permethrin. In some cases, surface concentration differed greatly from the fiber interior (>1 μm below the surface). Two- and three-dimensional mapping of Cl at sub-micrometer resolution showed permethrin to be dissolved throughout the fiber, with about 2 vol% residing in disperse, high-concentration domains. This suggests that these fibers fall into the class of monolithic sustained-release devices. It is expected that ToF-SIMS can be a valuable tool to provide insight into the insecticide release behavior of other LLIN products, both current and future.}, number={12}, journal={PLOS ONE}, author={Smith, Stephen C. and Zhou, Chuanzhen and Stevie, Fred A. and Garcia, Roberto}, year={2018}, month={Dec} }
 @article{klump_zhou_stevie_collazo_sitar_2018, title={Improvement in detection limit for time-of-flight SIMS analysis of dopants in GaN structures}, volume={36}, ISSN={["2166-2746"]}, DOI={10.1116/1.5013001}, abstractNote={Secondary ion mass spectrometry (SIMS) has been used extensively to monitor dopant levels in semiconductor materials. The preponderance of these measurements has been made with magnetic sector or quadrupole analyzers. Use of time-of-flight (ToF) analyzers has been limited because of an inability to match the detection limit of the other analyzers. Optimization of the ToF-SIMS analysis beam pulse width and analysis frames per cycle is shown to provide as much as an order of magnitude improvement in detection limit. The magnesium dopant in GaN structures was used for the study and analysis was made with Cs+ sputtering source and Bi3+. The count rate for CsMg+ increased by a factor of 11.3 with both improvements applied. This was evidenced by a detection limit improvement for magnesium from 7.5 × 1017 atoms/cm3 to low 1017 atoms/cm3. Increasing the number of analysis frames from one to ten causes cycle time to increase by a factor of five. Hence, there is a tradeoff between improved detection limit and analysis time.Secondary ion mass spectrometry (SIMS) has been used extensively to monitor dopant levels in semiconductor materials. The preponderance of these measurements has been made with magnetic sector or quadrupole analyzers. Use of time-of-flight (ToF) analyzers has been limited because of an inability to match the detection limit of the other analyzers. Optimization of the ToF-SIMS analysis beam pulse width and analysis frames per cycle is shown to provide as much as an order of magnitude improvement in detection limit. The magnesium dopant in GaN structures was used for the study and analysis was made with Cs+ sputtering source and Bi3+. The count rate for CsMg+ increased by a factor of 11.3 with both improvements applied. This was evidenced by a detection limit improvement for magnesium from 7.5 × 1017 atoms/cm3 to low 1017 atoms/cm3. Increasing the number of analysis frames from one to ten causes cycle time to increase by a factor of five. Hence, there is a tradeoff between improved detection limit and analy...}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Klump, Andrew and Zhou, Chuanzhen and Stevie, Frederick A. and Collazo, Ramon and Sitar, Zlatko}, year={2018}, month={May} }
 @article{zhou_stevie_smith_2018, title={Quantification of organic materials by ion implantation}, volume={36}, ISSN={["2166-2746"]}, DOI={10.1116/1.5011735}, abstractNote={Secondary ion mass spectrometry was initially considered to be a semiquantitative technique because of as much as 5 orders of magnitude variation in secondary ion yields over the periodic table for oxygen and cesium bombardment. The use of ion implantation to create standards has made it possible to accurately quantify elements and isotopes in a wide range of inorganic materials. The development of new ion sources has extended depth profiling to organic materials. It is of interest to explore ion implantation to quantify elements and molecular species in organic substrates. It is unrealistic to ion implant an organic molecule. Even if the molecular species was formed into a charged beam, the species will disintegrate upon impact with the substrate. However, if the species of interest contains an element not present in the substrate, then it should be possible to implant that element into the substrate and make a quantitative determination. In recent work, the authors demonstrated quantification of the ins...}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Zhou, Chuanzhen and Stevie, Fred A. and Smith, Stephen C.}, year={2018}, month={May} }
 @article{tuggle_pudasaini_stevie_kelley_palczewski_reece_2018, title={Secondary ion mass spectrometry for superconducting radiofrequency cavity materials}, volume={36}, ISSN={["2166-2746"]}, DOI={10.1116/1.5041093}, abstractNote={Historically, many advances in superconducting radio frequency (SRF) cavities destined for use in advanced particle accelerators have come empirically, through the iterative procedure of modifying processing and then performance testing. However, material structure is directly responsible for performance. Understanding the link between processing, structure, and performance will streamline and accelerate the research process. In order to connect processing, structure, and performance, accurate and robust materials characterization methods are needed. Here, one such method, secondary ion mass spectrometry (SIMS), is discussed with focus on the analysis of SRF materials. In addition, several examples are presented, showing how SIMS is being used to further understanding of material-based SRF technologies.Historically, many advances in superconducting radio frequency (SRF) cavities destined for use in advanced particle accelerators have come empirically, through the iterative procedure of modifying processing and then performance testing. However, material structure is directly responsible for performance. Understanding the link between processing, structure, and performance will streamline and accelerate the research process. In order to connect processing, structure, and performance, accurate and robust materials characterization methods are needed. Here, one such method, secondary ion mass spectrometry (SIMS), is discussed with focus on the analysis of SRF materials. In addition, several examples are presented, showing how SIMS is being used to further understanding of material-based SRF technologies.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Tuggle, Jay and Pudasaini, Uttar and Stevie, Fred A. and Kelley, Michael J. and Palczewski, Ari D. and Reece, Charlie E.}, year={2018}, month={Sep} }
 @article{zhou_stevie_smith_rading_zakel_2018, title={ToF-SIMS analysis of ion implanted standard to quantify insecticide in mosquito netting with cesium and argon gas cluster sputtering beams}, volume={36}, ISSN={["2166-2746"]}, DOI={10.1116/1.5011751}, abstractNote={Ion implantation has been investigated for quantification of species in organic materials. Quantitative analysis of two insecticides in mosquito netting was recently achieved by ion implantation and time-of-flight secondary ion mass spectroscopy analysis with a Cs+ sputtering beam [Zhou et al., J. Vac. Sci. Technol., B 34, 03H107 (2016) and Zhou et al., J. Vac. Sci. Technol., B 35, 031802 (2017)]. Gas cluster ion beams (GCIBs) are of increasing utility in depth profiling of organic materials, and it was of interest to try the ion implantation approach with argon GCIB. The study was conducted on permethrin treated mosquito netting and on the substrate material [high density polyethylene (HDPE)] which was ion implanted with chlorine. The negative ion mass spectrum of permethrin is dominated by Cl−. Analysis of the ion implanted HDPE with Cs+ provided the expected Gaussian distribution, but analysis with argon GCIB shows a very sharp change in matrix species intensity at the penetration depth of the ion impl...}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Zhou, Chuanzhen and Stevie, Fred A. and Smith, Stephen C. and Rading, Derk and Zakel, Julia}, year={2018}, month={May} }
 @article{stevie_2016, title={Analysis of hydrogen in materials with and without high hydrogen mobility}, volume={48}, ISSN={["1096-9918"]}, DOI={10.1002/sia.5930}, abstractNote={Hydrogen is a very important element but analysis of hydrogen in solids can be difficult and is not available for many analytical techniques. This paper provides an overview of the capabilities of SIMS and NRA to measure hydrogen concentrations and distributions. Bulk analysis methods provide an overall result, but depth profiles are often needed. SIMS can produce useful and quantifiable depth profiles for hydrogen and the isotopes deuterium and tritium. Hydrogen analysis at the surface and imaging with good lateral resolution can also be achieved with SIMS. However, hydrogen can have high mobility in a variety of materials and this will affect SIMS analysis. For those cases, other surface analysis methods such as hydrogen forward scattering and nuclear reaction analysis are preferred. Hydrogen analysis examples in silicon and in niobium are used for materials without and with high hydrogen mobility respectively. Copyright © 2016 John Wiley & Sons, Ltd.}, number={5}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Stevie, F. A.}, year={2016}, month={May}, pages={310–314} }
 @inproceedings{zhang_hengstebeck_stevie_hopstaken_2016, title={Improvement of hydrogen detection limit for quadruple SIMS tool}, DOI={10.1109/asmc.2016.7491119}, abstractNote={Hydrogen is an element of significant interest for semiconductor process; however it cannot be detected by many available elemental analysis techniques. Secondary ion mass spectrometry (SIMS) is one of the few techniques for the measurement of hydrogen amount and depth distribution. Among all kinds of SIMS tools, magnetic sector, quadrupole and time-of-flight, quadrupole SIMS instrument usually has lowest vacuum pressure and therefore should have better hydrogen detection limit. But high blast-through noise from mass 0 to mass 1 significantly affects the hydrogen detection limit. Various methods to improve hydrogen detection limit were investigated in this study. With field axis potential bias and higher mass edge measurement, hydrogen detection limit of quadrupole SIMS tool was improved by one order of magnitude to 2.2×1018 atoms/cm3.}, booktitle={2016 27th annual semi advanced semiconductor manufacturing conference (asmc)}, author={Zhang, Z. and Hengstebeck, B. and Stevie, F. A. and Hopstaken, M.}, year={2016}, pages={172–175} }
 @article{zhou_stevie_smith_2016, title={Method for quantification of insecticide in mosquito netting using ion implantation and ToF-SIMS analysis}, volume={34}, ISSN={["2166-2746"]}, DOI={10.1116/1.4940394}, abstractNote={Permethrin is used worldwide as a mosquito insecticide for netting and fabric. Permethrin is a contact insecticide so only the permethrin on the surface can directly impact the mosquito. Therefore, knowledge of the surface concentration of the insecticide is essential to measure the effectiveness of the treated material. Time-of-flight secondary ion mass spectrometry analysis of permethrin showed Cl− as the predominant species in the negative ion mass spectrum. The netting material in this study is composed of high density polyethylene (HDPE). Ion implantation was used to place a known amount of chlorine into the netting material, sheet HDPE, and silicon samples. Depth profile analysis of the implanted samples showed distinct chlorine implant profiles, with the silicon sample used to verify implant dose. Quantification and detection limit for chlorine have been obtained for HDPE sheet and netting. The chlorine detection limit in HDPE is approximately 2 × 1018 atoms/cm3, and the chlorine concentration in n...}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Zhou, Chuanzhen and Stevie, Fred A. and Smith, Stephen C.}, year={2016} }
 @article{stevie_zhou_hopstaken_saccomanno_zhang_turansky_2016, title={SIMS measurement of hydrogen and deuterium detection limits in silicon: Comparison of different SIMS instrumentation}, volume={34}, ISSN={["2166-2746"]}, DOI={10.1116/1.4940151}, abstractNote={Hydrogen is the most abundant element in the universe, but it cannot be detected by many analytical techniques. This element is used to improve interface quality and reduce the impact of defects in silicon technology. Knowledge of the amount and distribution of hydrogen is of significant interest for many technologies, such as ZnO and glass manufacturing. Secondary ion mass spectrometry (SIMS) can provide analysis for hydrogen and the isotopes deuterium and tritium. Lower instrument vacuum will improve the hydrogen detection limit. Vacuum conditions can be optimized by methods such as overnight pumping of samples and sample holder heating. Adsorption of hydrogen from the vacuum environment during analysis can be minimized with use of high sputtering rate. The species monitored may be atomic or molecular, such as H− or Cs2H+. The latter species provides a practical means for hydrogen profiling in dielectric films in magnetic sector instruments with conventional charge compensation. It is of interest to com...}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Stevie, Fred A. and Zhou, Chaunzhen and Hopstaken, Marinus and Saccomanno, Michael and Zhang, Zhichun and Turansky, Andrew}, year={2016} }
 @article{stevie_2015, title={SRF Niobium Characterization Using SIMS and FIB-TEM}, volume={1687}, ISSN={["0094-243X"]}, DOI={10.1063/1.4935321}, abstractNote={Our understanding of superconducting radio frequency (SRF) accelerator cavities has been improved by elemental analysis at high depth resolution and by high magnification microscopy. This paper summarizes the technique development and the results obtained on poly-crystalline, large grain, and single crystal SRF niobium. Focused ion beam made possible sample preparation using transmission electron microscopy and the images obtained showed a very uniform oxide layer for all samples analyzed. Secondary ion mass spectrometry indicated the presence of a high concentration of hydrogen and the hydrogen content exhibited a relationship with improvement in performance. Depth profiles of carbon, nitrogen, and oxygen did not show major differences with heat treatment. Niobium oxide less than 10 nm thick was shown to be an effective hydrogen barrier. Niobium with titanium contamination showed unexpected performance improvement.}, journal={SCIENCE AND TECHNOLOGY OF INGOT NIOBIUM FOR SUPERCONDUCTING RADIO FREQUENCY APPLICATIONS}, author={Stevie, F. A.}, year={2015} }
 @article{stevie_garcia_richardson_zhou_2014, title={Back side SIMS analysis}, volume={46}, ISSN={["1096-9918"]}, DOI={10.1002/sia.5470}, abstractNote={Depth profiling SIMS analysis to determine diffusion of an element from a surface layer into a substrate or penetration of a species through a barrier layer can be very difficult to achieve because one cannot readily detect a trace amount of an element after depth profiling through a matrix level of the same element. Removal of the substrate and analysis from the back of the sample has provided a solution to this problem. Substrate removal methods have been either mechanical polish followed by a chemical etch or mechanical polish alone. The latter method has provided successful results for a wide range of studies including penetration of Cu though a barrier material, diffusion from high‐k dielectric layers, and site specific analysis on a product wafer. In order to make the polishing method more routine and reduce the time required, substrate removal was investigated with use of a milling machine designed to de‐process packaged semiconductor devices. Initial work on an Si substrate shows residual Si less than 100 nm could be obtained in a region that was subsequently analyzed with good depth resolution in a SIMS depth profile. Mesa sample preparation with this instrument was also demonstrated. Copyright © 2014 John Wiley & Sons, Ltd.}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Stevie, F. A. and Garcia, R. and Richardson, C. and Zhou, C.}, year={2014}, month={Nov}, pages={241–243} }
 @article{stevie_sedlacek_babor_jiruse_principe_klosova_2014, title={FIB-SIMS quantification using TOF-SIMS with Ar and Xe plasma sources}, volume={46}, ISSN={["1096-9918"]}, DOI={10.1002/sia.5483}, abstractNote={A novel time of flight SIMS analyzer provides a new approach to SIMS analysis as an addition to a focused ion beam SEM instrument. The combination of this analyzer with a high current plasma ion source offers new opportunities for analysis, particularly in the study of coatings, which require ultra‐deep profiling. Use of this instrumentation showed the ability to detect and quantify a number of elements. Quantification was obtained for Li, Na, K ion implanted in Si and for B in a sample with known concentration. Use of the electron beam from the electron column permitted analysis of 300‐nm SiO2/Si implanted with BF2. Copyright © 2014 John Wiley & Sons, Ltd.}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Stevie, F. A. and Sedlacek, L. and Babor, P. and Jiruse, J. and Principe, E. and Klosova, K.}, year={2014}, month={Nov}, pages={285–287} }
 @article{maheshwari_stevie_myneni_ciovati_rigsbee_dhakal_griffis_2014, title={SIMS analysis of high-performance accelerator niobium}, volume={46}, ISSN={["1096-9918"]}, DOI={10.1002/sia.5461}, abstractNote={Niobium is used to fabricate superconducting radio frequency accelerator modules because of its high critical temperature, high critical magnetic field, and easy formability. Recent experiments have shown a very significant improvement in performance (over 100%) after a high‐temperature bake at 1400 °C for 3 h. SIMS analysis of this material showed the oxygen profile was significantly deeper than the native oxide with a shape that is indicative of diffusion. Positive secondary ion mass spectra showed the presence of Ti with a depth profile similar to that of O. It is suspected that Ti is associated with the performance improvement. The source of Ti contamination in the anneal furnace has been identified, and a new furnace was constructed without Ti. Initial results from the new furnace do not show the yield improvement. Further analyses should determine the relationship of Ti to cavity performance. Copyright © 2014 John Wiley & Sons, Ltd.}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Maheshwari, P. and Stevie, F. A. and Myneni, G. R. and Ciovati, G. and Rigsbee, J. M. and Dhakal, P. and Griffis, D. P.}, year={2014}, month={Nov}, pages={288–290} }
 @article{stevie_maheshwari_pierce_adekore_griffis_2013, title={SIMS analysis of zinc oxide LED structures: quantification and analysis issues}, volume={45}, ISSN={["1096-9918"]}, DOI={10.1002/sia.4919}, abstractNote={Zinc oxide (ZnO) is a wide band gap semiconductor that shows great promise for development of light emitting diode structures. Interest in this technology has increased significantly, but even though controlled n‐type doping can be readily achieved, p‐type doping has been difficult. Numerous potential p‐type dopants were investigated in this SIMS study using a CAMECA IMS‐6F. The dopants and other elements of interest were quantified by use of ion implantation into ZnO substrates. Relative sensitivity factor values were obtained for H, Li, N, F, Na, Mg, Al, Si, K, Ga, As, Se, Ag, Cd, Te. Sample charging was encountered for some specimens, and adjacent electron neutralization procedures were employed. ZnO structures were prepared and subsequently analyzed with both O2+ and Cs+ primary beams. Depth profiles exposed a number of analysis issues. Because of the large number of elements, especially those at low atomic number, that were present in the structures, many mass interferences were encountered. Ag in particular was very difficult to monitor. Matrix effects were also noted, especially when high Mg doping was used. The need to monitor Al, Na, and K in the near surface region required analysis without conductive Au coating to reduce contamination. With careful choice of secondary ion species, it was possible to monitor the elements of primary interest using O2+ primary beam. SIMS demonstrated the ability to characterize the layers in the ZnO structure, including quantum wells, and to determine dopant and contaminant levels. Copyright © 2012 John Wiley & Sons, Ltd.}, number={1}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Stevie, F. A. and Maheshwari, P. and Pierce, J. M. and Adekore, B. T. and Griffis, D. P.}, year={2013}, month={Jan}, pages={352–355} }
 @article{santeufemio_gorman_zhou_giannuzzi_stevie_2013, title={TOF SIMS analyses of stray Ga during FIB milling}, volume={31}, ISSN={["0734-2101"]}, DOI={10.1116/1.4825403}, abstractNote={A blind study using two different 30 keV state-of-the-art Ga+ focused ion beam (FIB) columns was performed to analyze the surface concentration of Ga as a function of distance from a FIB milled feature. Time of flight secondary ion mass spectrometry was used to measure Ga surface and near surface concentration by a series of depth profiles at a distance up to 6.5 mm from a 100 μm ×100 μm constant dose FIB milled square. In column “A,” >1 × 1012 atoms/cm2 of Ga was detected up to ∼5 mm from the FIB milled square. Column “B” showed considerably less Ga but still detected >1 × 1012 atoms/cm2 at ∼250 μm from the FIB milled square. The depth profiles show that the Ga concentration was similar to a depth of ∼1 nm from the surface for both columns, indicating that these implantation depths correspond to a particle energy <250 eV. The low energy presence of Ga far from the intended region of interest was likely due to either secondary sputtering from instrument optics and other structures near the sample, or rede...}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Santeufemio, Christopher and Gorman, Brian P. and Zhou, Chuanzhen and Giannuzzi, Lucille A. and Stevie, Fred A.}, year={2013} }
 @article{penley_stevie_griffis_2012, title={Quantification of cesium surface contamination on silicon resulting from SIMS analysis}, volume={30}, ISSN={["2166-2746"]}, DOI={10.1116/1.3698400}, abstractNote={In order to improve the understanding of unintended cesium (Cs) contamination that occurs during SIMS depth profiling, Cs concentrations on sample surfaces were measured before analysis and at various distances from a depth profile crater after analysis. Cs concentrations in excess of 1 at. % were found directly adjacent to the depth profile analysis site. Cs was also detected at significant concentrations hundreds of micrometers from the depth profile measurement location. This Cs contamination can originate from a number of sources including Cs beam tails, Cs neutral beam, and secondary sputtering from instrument optics and other structures. Since the presence of cesium significantly affects the secondary ion yield of electronegative elements (e.g., phosphorus) in silicon, the unintended presence of cesium on the surface of a previously analyzed sample can strongly affect the reproducibility and accuracy of low dose electronegative element measurements, especially at the surface.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Penley, C. and Stevie, F. A. and Griffis, D. P.}, year={2012} }
 @article{maheshwari_stevie_myeneni_ciovati_rigsbee_griffis_2011, title={Analysis of Interstitial Elements in Niobium with Secondary Ion Mass Spectrometry (SIMS)}, volume={1352}, ISBN={["978-0-7354-0909-5"]}, ISSN={["0094-243X"]}, DOI={10.1063/1.3579233}, abstractNote={Superconducting Radio Frequency (SRF) cavities provide enhanced efficiency and reduced energy utilization in present day particle accelerators. Niobium (Nb) is the material of choice for these cavities due to its high critical temperature and critical magnetic field. In order to understand why certain treatments, especially a low temperature bake, improve performance, it is important to study Nb surface characteristics and identify elemental contamination that can affect the performance of the cavity. H, C, O, and N are of interest because they are interstitial impurities in Nb. In earlier work, SIMS analysis using a CAMECA IMS‐6F with Cs+ primary beam showed that C and N were probably not significant factors impacting performance but there was a very high level of H in the Nb. Ion implants of C, N, O, and D into Nb provided quantification of C, N, O and indicated that D is very mobile in the Nb. Further analyses showed that heat treated Nb has lower levels of surface H than non heat treated Nb and subseq...}, journal={INTERNATIONAL SYMPOSIUM ON THE SUPERCONDUCTING SCIENCE & TECHNOLOGY OF INGOT NIOBIUM}, author={Maheshwari, P. and Stevie, F. A. and Myeneni, G. and Ciovati, G. and Rigsbee, J. M. and Griffis, D. P.}, year={2011}, pages={151-+} }
 @article{maheshwari_tian_reece_kelley_myneni_stevie_rigsbee_batchelor_griffis_2011, title={Surface analysis of Nb materials for SRF cavities}, volume={43}, ISSN={["1096-9918"]}, DOI={10.1002/sia.3513}, abstractNote={Superconducting Radio Frequency (SRF) cavities provide enhanced efficiency and reduced energy consumption in present‐day particle accelerators. Niobium is the material of choice for SRF cavities due to its high critical temperature and critical magnetic field. In order to understand why certain treatments, especially a low temperature bake, improve performance, it is important to study Nb surface characteristics and identify elemental contaminants which may affect the performance of the cavity. 1 Initial studies using SIMS and Focused Ion Beam (FIB) prepared specimens for Transmission Electron Microscopy (TEM) have helped to characterize the Nb surface and measure the surface oxide layer thickness. 2 C, N and O are of particular interest as interstitial contaminants and earlier studies suggested very high H concentration. In the present study, ion implants of C, N, O and deuterium (D) in Nb and Si were analyzed using SIMS. D was implanted to characterize H while avoiding interference from the high H background. The D implant was easily detectable in Si, but showed a constant value and no implant shape in Nb. This result implies either that D (and by implication, hydrogen) has a high mobility in Nb, or that there is movement of D due to the primary ion beam. Nevertheless, C, N, and O could be quantified using the ion implants. Depth profiles of polycrystalline and single crystal Nb samples were also obtained. While both types of Nb samples contained low C concentration, the single crystal Nb samples showed higher N and O content. Copyright © 2010 John Wiley & Sons, Ltd.}, number={1-2}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Maheshwari, P. and Tian, H. and Reece, C. E. and Kelley, M. J. and Myneni, G. R. and Stevie, F. A. and Rigsbee, J. M. and Batchelor, A. D. and Griffis, D. P.}, year={2011}, pages={151–153} }
 @article{ciovati_myneni_stevie_maheshwari_griffis_2010, title={High field Q slope and the baking effect: Review of recent experimental results and new data on Nb heat treatments}, volume={13}, ISSN={["1098-4402"]}, DOI={10.1103/physrevstab.13.022002}, abstractNote={Here, the performance of superconducting radio-frequency (SRF) cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT) is characterized by exponentially increasing rf losses (high-field Q-slope), in the absence of field emission, which are often mitigated by low temperature (100-140 °C, 12-48 h) baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q-slope will be presented for cavities that had been heat treated in a vacuum furnace at high temperature without subsequent chemical etching. These studies are aimed at understanding the role of hydrogen on the high-field Q-slope and at the passivation of the Nb surface during heat treatment. Improvement of the cavity performances, particularly of the cavities’ quality factor, have been obtained following the high temperature heat-treatments, while SIMS surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.}, number={2}, journal={PHYSICAL REVIEW SPECIAL TOPICS-ACCELERATORS AND BEAMS}, author={Ciovati, G. and Myneni, G. and Stevie, F. and Maheshwari, P. and Griffis, D.}, year={2010}, month={Feb} }
 @article{penley_stevie_griffis_siebel_kulig_lee_2010, title={Secondary ion mass spectrometry characterization of anomalous behavior for low dose ion implanted phosphorus in silicon}, volume={28}, ISSN={["2166-2746"]}, DOI={10.1116/1.3406141}, abstractNote={Significant changes over time have been observed in surface and near surface phosphorus concentration for low dose phosphorus implants measured using secondary ion mass spectrometry (SIMS) with cesium bombardment. These variations in concentration affect the ability to make reproducible dose measurements. Phosphorus measurements have been documented for samples from wafers kept at ambient conditions and also for those stored in a range of other conditions including heat, high humidity, low humidity, and liquid nitrogen. An initial study of wafers ion implanted over a range of doses showed that the change in the surface phosphorus concentration was most apparent for the lowest phosphorus dose (1×1012 atoms/cm2) and that heating the sample resulted in the most significant change (increase in almost three orders of magnitude) in apparent surface P concentration. Only the specimens stored at liquid nitrogen temperature showed no change in P surface concentration. SIMS analysis conditions were optimized and a ...}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Penley, C. and Stevie, F. A. and Griffis, D. P. and Siebel, S. and Kulig, L. and Lee, J.}, year={2010}, month={May}, pages={511–516} }
 @article{bishop_reynolds_molstad_stevie_barnhardt_davis_2009, title={On the origin of aluminum-related cathodoluminescence emissions from sublimation grown 4H-SiC(11(2)over-bar0)}, volume={255}, ISSN={["0169-4332"]}, DOI={10.1016/j.apsusc.2009.02.036}, abstractNote={The spatial origins of emissions from homoepitaxial 4H-SiC(112¯0) films have been investigated by cathodoluminescence, secondary ion mass spectrometry, and electron trajectory simulations. At 15 keV (300 K), the spectrum contained three peaks. The most intense peak corresponded (3.18 eV) to the nitrogen donor-to-valence band transition. The lesser two peaks at 2.94 eV and 2.75 eV involved aluminum and oxygen impurities, respectively; both impurities were determined to be in high concentrations in the film–substrate interfacial region. At 25 keV (300 K) the primary emission broadened into a band at ∼3.10 eV. Deconvolution revealed three peaks; the most intense emission was again the nitrogen donor-to-valence band transition. The remaining two peaks at 3.02 eV and 2.90 eV were consistent with transitions involving aluminum impurities. The former peak was not observed in the spectra obtained at lower electron beam energies and was correlated with the conduction band-to-aluminum acceptor level transition. Monte-Carlo simulations showed the origin of the 25 keV (300 K) spectrum was the film–substrate interface. An analysis of the aluminum impurity concentration in this region revealed that the cause of the 3.02 eV emission was a dramatic increase in the concentration of aluminum (3 × 1016 cm−3 to 1 × 1018 cm−3). The emissions comprising the 3.10 eV band were further investigated at 6 K and 25 keV. The difference in the intensity of the conduction band-to-aluminum acceptor level transition at 6 K and 300 K was attributed to thermal impurity ionization and the spike in the interfacial aluminum concentration previously described.}, number={13-14}, journal={APPLIED SURFACE SCIENCE}, author={Bishop, S. M. and Reynolds, C. L. and Molstad, J. C. and Stevie, F. A. and Barnhardt, D. E. and Davis, R. F.}, year={2009}, month={Apr}, pages={6535–6539} }
 @article{zhu_stevie_griffis_2008, title={Model study of electron beam charge compensation for positive secondary ion mass spectrometry using a positive primary ion beam}, volume={254}, DOI={10.1016/j.apsusc.2007.10.008}, abstractNote={A new modeling approach has been developed to assist in the SIMS analysis of insulating samples. This approach provides information on the charging phenomena occurring when electron and positive primary ion beams impact a low conductivity material held at a high positive potential. The concept of effective leakage resistance aids in the understanding of the dynamic electrical properties of an insulating sample under dynamic analysis conditions. Modeling of steady state electron beam charge compensation involves investigation of electron injection and charge drift. Using a Monte Carlo program to simulate electron injection and dc conduction calculations to predict charge drift, detailed information regarding charging phenomena can be determined.}, number={9}, journal={Applied Surface Science}, author={Zhu, Z. M. and Stevie, F. A. and Griffis, D. P.}, year={2008}, pages={2708–2711} }
 @article{stevie_griffis_2008, title={Quantification in dynamic SIMS: Current status and future needs}, volume={255}, ISSN={["0169-4332"]}, DOI={10.1016/j.apsusc.2008.05.041}, abstractNote={Dynamic SIMS has made great strides in quantification. The use of ion-implanted standards has made quantification routine for any element in a wide range of matrices. Both contaminant and matrix measurements can be reliably quantified in the same depth profile for selected multi-element substrates, such as SiGe and AlGaN. Dose measurements with less than 1% reproducibility have been demonstrated for magnetic sector, quadrupole, and time-of-flight instruments. Progress has been made in quantification at the surface, at interfaces, in thin layers, in insulators, within small areas, and for two and three dimensions. Current challenges include quantification in a proliferation of layers, interfaces, and elements, and obtaining quantitative information from the smallest possible area. Analyses using complementary techniques will be useful for these difficult SIMS measurements. Focused ion beam specimen preparation has shown promise for small area and three-dimensional analyses. Developments in ion sources show potential for small area analysis using focused ion beam SIMS.}, number={4}, journal={APPLIED SURFACE SCIENCE}, author={Stevie, F. A. and Griffis, D. P.}, year={2008}, month={Dec}, pages={1364–1367} }
 @article{bishop_reynolds_liliental-weber_uprety_ebert_stevie_park_davis_2008, title={Sublimation growth of an in-situ-deposited layer in SiC chemical vapor deposition on 4H-SiC(1 1 (2)over-bar 0)}, volume={311}, ISSN={["1873-5002"]}, DOI={10.1016/j.jcrysgro.2008.09.200}, abstractNote={Homoepitaxial growths of 4H-SiC(1 1 2¯ 0) epitaxial layers have been achieved using chemical vapor deposition from 1250 to 1600 °C and two process routes: (1) with and (2) without the addition of SiH4 and C2H4 to the growth ambient. An activation energy of 3.72 eV/atom (359 kJ/mol) was determined for the former route and associated with either reactions in the gas phase or the potential barrier associated with the temperature-dependent sticking coefficient. The activation energy for the latter route was 5.64 eV/atom (544 kJ/mol), which is consistent with published values for SiC sublimation epitaxy. Sublimation dominated the growth process at temperature ⩾1600 °C. The same effect resulted in the in-situ deposition of a thin film during the heating stage of route (1). At 1450 °C this layer was ∼100 nm thick and exhibited a specular surface microstructure with a roughness of 0.31 nm RMS. The in-situ-deposited layer was thus employed as an intermediate layer prior to epitaxial layer growth using route (1) at ∼1450 °C. Regions free of one- and two-dimensional defects were observed using cross-sectional transmission electron microscopy. Distinct interfaces were not observed between the substrate and the epitaxial layers.}, number={1}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Bishop, S. M. and Reynolds, C. L., Jr. and Liliental-Weber, Z. and Uprety, Y. and Ebert, C. W. and Stevie, F. A. and Park, J. -S. and Davis, R. F.}, year={2008}, month={Dec}, pages={72–78} }
 @article{harton_zhu_stevie_aoyama_ade_2007, title={Carbon-13 labeling for quantitative analysis of molecular movement in heterogeneous organic materials using secondary ion mass spectrometry}, volume={79}, ISSN={["1520-6882"]}, DOI={10.1021/ac070437q}, abstractNote={Secondary ion mass spectrometry (SIMS) is used to probe the movement of macromolecules in heterogeneous organic systems. Using 13C tracer labeling and two model systems, polystyrene/poly(2-vinylpyridine) (PS/P2VP) and polystyrene/poly(4-bromostyrene) (PS/P4BrS), the diffusion of 13C-labeled PS has been investigated near the respective heterogeneous interfaces using a CAMECA-IMS-6F magnetic sector mass spectrometer. 13C labeling has been shown to greatly minimize matrix effects (i.e., changes in secondary ion yields due to changing chemical environment) in heterogeneous systems. P2VP is a nitrogen-rich polymer (C7H7N monomer composition), making it an excellent model polymer for exploration of this technique for potential future use in biological applications, and probing the PS/P4BrS interface demonstrates the versatility of this technique for analysis of various heteroatom-containing materials. Results confirm that the 13C-labeling method does indeed allow for quantitative analysis of molecular movement in heterogeneous organic systems containing matrix-enhancing heteroatoms such as nitrogen. Therefore, extension of this method to more complicated biological systems involving multiple heteroatoms (oxygen, nitrogen, etc.), layers, and heterogeneous interfaces, as well as two- and three-dimensional profiling and imaging using SIMS, can be envisaged.}, number={14}, journal={ANALYTICAL CHEMISTRY}, author={Harton, Shane E. and Zhu, Zhengmao and Stevie, Frederick A. and Aoyama, Yoko and Ade, Harald}, year={2007}, month={Jul}, pages={5358–5363} }
 @article{zhu_gu_stevie_griffis_2007, title={Improved understanding of an electron beam charge compensation method for magnetic sector secondary ion mass spectrometer analysis of insulators}, volume={25}, ISSN={["0734-2101"]}, DOI={10.1116/1.2746044}, abstractNote={Good charge compensation has historically been difficult to achieve for secondary ion mass spectrometry positive secondary ion depth profile analysis of highly insulating samples using a magnetic sector secondary ion mass spectrometer. A new charge compensation method has been developed utilizing an adjacent electron beam approach. A combination of computational simulation and quantitative characterization of the charge compensation phenomenon was used to elucidate the underlying mechanisms of this charge compensation technique with the goal of further improving this method. Results of this approach show that a low intensity electron shower consisting of secondary and backscattered electrons resulting from the impact of the primary electron beam with elements in the electron beam flight path may be responsible for charge compensation. It is also determined that the charge compensation provided by the adjacent impact technique can be further improved to provide better profile stability, higher mass resolut...}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Zhu, Z. and Gu, C. and Stevie, F. A. and Griffis, D. P.}, year={2007}, pages={769–774} }
 @article{harton_zhu_stevie_griffis_ade_2007, title={Mass fractionation of carbon and hydrogen secondary ions upon Cs+ and O-2(+) bombardment of organic materials}, volume={25}, ISSN={["1520-8559"]}, DOI={10.1116/1.2718957}, abstractNote={A phenomenon known as mass fractionation has been probed in organic materials using secondary ion mass spectrometry (SIMS). Mass fractionation occurs because two isotopes of a particular species (i.e., identical number of protons, but different number of neutrons) do not have identical secondary ion yields in a constant chemical environment. Two primary ion probes, Cs+ and O2+, have been utilized with detection of negative and positive secondary ions, respectively, using a magnetic sector mass spectrometer. These two analysis conditions have been found to yield considerably different mass fractionation effects as a result of different sputtering and ionization mechanisms. Also, as determined previously with SIMS analysis of inorganic materials, the lower molecular weight species carbon and hydrogen are particularly susceptible to mass fractionation effects. Because organic materials are primarily composed of carbon and hydrogen, and because isotopic labeling is often utilized to accurately analyze such ma...}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Harton, Shane E. and Zhu, Zhengmao and Stevie, Frederick A. and Griffis, Dieter P. and Ade, Harald}, year={2007}, pages={480–484} }
 @article{gu_stevie_bennett_garcia_griffis_2006, title={Back side SIMS analysis of hafnium silicate}, volume={252}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2006.02.099}, abstractNote={Abstract High-k dielectrics are under study as part of the effort to continually reduce semiconductor device dimensions and hafnium silicate (HfSixOy) is one of the most promising high-k materials. A requirement of the dielectric is that the constituent elements cannot diffuse into adjacent device regions during thermal processing. Analysis for inter-diffusion using front side SIMS of high-k dielectrics has been complicated by matrix and sputtering effects. Use of a back side analysis sample preparation procedure that was successful for copper diffusion and site specific studies produced a HfSiO specimen that has less than 250 nm silicon remaining and minimal slope over the analysis region. Magnetic Sector (CAMECA IMS-6F) SIMS analysis of this specimen with low energy O2+ bombardment does not show the matrix and sputtering effects noted in the front side data. Sufficient depth resolution was obtained to define the interface between the silicon substrate and the HfSiO layer and indicate what appears to be an interfacial layer. There is no indication of hafnium diffusion into the silicon substrate.}, number={19}, journal={APPLIED SURFACE SCIENCE}, publisher={Elsevier BV}, author={Gu, C. and Stevie, F. A. and Bennett, J. and Garcia, R. and GriffiS, D. P.}, year={2006}, month={Jul}, pages={7179–7181} }
 @article{harton_stevie_zhu_ade_2006, title={Carbon-13 labeled polymers: An alternative tracer for depth profiling of polymer films and multilayers using secondary ion mass spectrometry}, volume={78}, ISSN={["1520-6882"]}, DOI={10.1021/ac060133o}, abstractNote={13C labeling is introduced as a tracer for depth profiling of polymer films and multilayers using secondary ion mass spectrometry (SIMS). Deuterium substitution has traditionally been used in depth profiling of polymers but can affect the phase behavior of the polymer constituents with reported changes in both bulk-phase behavior and surface and interfacial interactions. SIMS can provide contrast by examining various functional groups, chemical moieties, or isotopic labels. 13C-Labeled PS (13C-PS) and unlabeled PS (12C-PS) and PMMA were synthesized using atom-transfer radical polymerization and assembled in several model thin-film systems. Depth profiles were recorded using a Cameca IMS-6f magnetic sector mass spectrometer using both 6.0-keV impact energy Cs+ and 5.5-keV impact energy O2+ primary ion bombardment with detection of negative and positive secondary ions, respectively. Although complete separation of 12C1H from 13C is achieved using both primary ion species, 6.0-keV Cs+ clearly shows improved detection sensitivity and signal-to-noise ratio for detection of 12C, 12C1H, and 13C secondary ions. The use of Cs+ primary ion bombardment results in somewhat anomalous, nonmonotonic changes in the 12C, 12C1H, and 13C secondary ion yields through the PS/PMMA interface; however, it is shown that this behavior is not due to sample charging. Through normalization of the 13C secondary ion yield to the total C (12C + 13C) ion yield, the observed effects through the PS/PMMA interface can be greatly minimized, thereby significantly improving analysis of polymer films and multilayers using SIMS. Mass spectra of 13C-PS and 12C-PS were also analyzed using a PHI TRIFT I time-of-flight mass spectrometer, with 15-keV Ga+ primary ion bombardment and detection of positive secondary ions. The (12)C7(1)H7 ion fragment and its 13C-enriched analogues have significant secondary ion yields with negligible mass interferences, providing an early indication of the potential for future use of this technique for cluster probe depth profiling of high molecular weight 13C-labeled fragments.}, number={10}, journal={ANALYTICAL CHEMISTRY}, author={Harton, S. E. and Stevie, F. A. and Zhu, Z. and Ade, H.}, year={2006}, month={May}, pages={3452–3460} }
 @article{harton_stevie_ade_2006, title={Carbon-13 labeling for improved tracer depth profiling of organic materials using secondary ion mass spectrometry}, volume={17}, ISSN={["1879-1123"]}, DOI={10.1016/j.jasms.2006.03.018}, abstractNote={13C labeling is introduced as an alternative to deuterium labeling for analysis of organic materials using secondary ion mass spectrometry (SIMS). A model macromolecular system composed of polystyrene (PS) and poly(methyl methacrylate) (PMMA) was used to compare the effects of isotopic labeling using both deuterium substitution (dPS) and 13C labeling (13C-PS). Clear evidence is shown that deuterium labeling does introduce changes in the thermodynamic properties of the system, with the observation of segregation of dPS to an hPS:dPS/hPMMA interface. This type of behavior could significantly impact many types of investigations due to the potential for improper interpretation of experimental results as a consequence of labeling-induced artifacts. 13C labeling is shown to provide a true tracer for analysis using SIMS.}, number={8}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY}, author={Harton, S. E. and Stevie, F. A. and Ade, H.}, year={2006}, month={Aug}, pages={1142–1145} }
 @article{salman_chow_chai_stevie_2006, title={Diffusion behavior of implanted Li ions in GaN thin films studied by secondary ion mass spectrometry}, volume={9}, ISSN={["1369-8001"]}, DOI={10.1016/j.mssp.2006.01.020}, abstractNote={Lithium ions with dosages of 2.6×1012, 2.6×1013, 2.6×1014, and 2.6×1015 cm−2 have been implanted into a GaN thin film grown on sapphire substrates. The diffusion behavior of these implanted Li ions in GaN thin film at different temperature anneals was studied using secondary ion mass spectrometry. In general, the diffusion profiles show relatively little movement of Li in the GaN thin film for temperatures up to 700 °C. At low-temperature anneals (<500 °C), up-hill diffusion dominated the Li profiles and at high-temperature anneals (>800 °C), out-diffusion dominated the Li profiles.}, number={1-3}, journal={MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING}, author={Salman, F. and Chow, L. and Chai, B. and Stevie, F. A.}, year={2006}, pages={375–379} }
 @article{salman_zhang_chow_stevie_2006, title={Diffusion profiles of low dosages chromium ions implanted into (100) crystalline silicon}, volume={9}, ISSN={["1369-8001"]}, DOI={10.1016/j.mssp.2006.01.010}, abstractNote={Chromium ions with low dosages (1×1012 and 1×1013 cm−2) are implanted into silicon (1 0 0) crystalline substrates. Thermal anneals were carried out at different temperatures between 300 and 1000 °C to study the effects of ion implantation dose on the Cr diffusion profiles. Secondary ion mass spectrometry (SIMS) has been used to characterize the profiles of the Cr impurities. At 1×1012 cm−2 dosage and 500 °C anneal, the diffusivity of Cr in Silicon is determined to be 1.0×10−14 cm2 s−1.}, number={1-3}, journal={MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING}, author={Salman, F. and Zhang, P. and Chow, L. and Stevie, F. A.}, year={2006}, pages={62–65} }
 @article{harton_stevie_ade_2006, title={Investigation of the effects of isotopic labeling, at a PS/PMMA interface using SIMS and mean-field theory}, volume={39}, ISSN={["1520-5835"]}, DOI={10.1021/ma052236z}, abstractNote={Isotopic labeling (deuteration) is known to affect the phase behavior of polystyrene (PS) and poly- (methyl methacrylate) (PMMA) blends, but little is known regarding the changes in the interfacial properties at the PS/PMMA interface due to deuteration of PS and/or PMMA. To investigate these potential changes, secondary ion mass spectrometry (SIMS) was used to measure real-space depth profiles of dPS in hPS:dPS/hPMMA bilayers, with the hPS:dPS blend being well within the single-phase region of the phase diagram. Profound changes in the thermodynamic behavior of this system at the polymer/polymer interface are observed in the form of significant segregation of dPS to the hPS:dPS/hPMMA interface. The observation of a depletion hole during the formation of an equilibrium excess of dPS implies that the energetic gain at the interface per dPS chain has to be >kT. These results cannot be described, even qualitatively, using previously reported changes in for PS/PMMA due to isotopic labeling. The previously reported values of for dPS/hPMMA and hPS/hPMMA actually predict a depletion of dPS at the hPS:dPS/hPMMA interface rather than the observed segregation. The observed interfacial excess is quantified by generating theoretical profiles, using self-consistent mean-field theory (SCMF), and fitting an effective interaction energy parameter ¢ p as a function of temperature. This parameter represents the asymmetry in dPS/hPMMA and hPS/PMMA interactions. The temperature dependency of ¢ p was found to be a factor of 3-4 greater than any of those reported for of PS/PMMA. It was also found that SCMF theory accurately describes the concentration dependency of dPS segregation at a constant dPS molecular weight using a concentration-independent ¢ p; however, ¢ p was found to be dependent on dPS molecular weight.}, number={4}, journal={MACROMOLECULES}, author={Harton, SE and Stevie, FA and Ade, H}, year={2006}, month={Feb}, pages={1639–1645} }
 @article{harton_stevie_griffis_ade_2006, title={SIMS depth profiling of deuterium labeled polymers in polymer multilayers}, volume={252}, ISSN={["0169-4332"]}, DOI={10.1016/j.apsusc.2006.02.146}, abstractNote={Abstract Thin planar polymer films are model systems for probing physical phenomena related to molecular confinement at polymer surfaces and polymer/polymer interfaces. Existing experimental techniques such as forward recoil spectrometry (FRES) and neutron reflectometry (NR) have been used extensively for analysis of these systems, although they suffer from relatively low depth resolution (FRES) or difficulties associated with inversion to real space (NR). In contrast, secondary ion mass spectrometry (SIMS) can provide real-space depth profiles of tracer labeled polymers directly with sufficient depth resolution for optimal analyses of these systems. Deuterated polystyrene (dPS) has been employed as the tracer polymer and has been embedded in a matrix of either unlabeled polystyrene (PS) or poly(cyclohexyl methacrylate) (PCHMA). These doped films have been placed on either poly(methyl methacrylate) (PMMA) or poly(2-vinyl pyridine) (P2VP) and thermally annealed. Varied analysis conditions for a magnetic sector SIMS instrument (CAMECA IMS-6f) were used to optimize the depth resolution and detection sensitivity while minimizing matrix effects and sample charging. Both Cs+ and O2+ primary ions have been used along with detection of negative and positive secondary ions, respectively. Impact energy and primary ion species have been shown to affect matrix secondary ion count rate for the various films studied.}, number={19}, journal={APPLIED SURFACE SCIENCE}, author={Harton, Shane E. and Stevie, Fred A. and Griffis, Dieter P. and Ade, Harald}, year={2006}, month={Jul}, pages={7224–7227} }
 @article{gu_stevie_hitzman_saripalli_johnson_griffis_2006, title={SIMS quantification of matrix and impurity species in AlxGa1-xN}, volume={252}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2006.02.148}, abstractNote={The quantification in Al x Ga 1-x N with different AlN mole fraction (x) is challenging because of matrix effects and charging effects. For quantitative characterization of both matrix and impurity elements in Al x Ga 1-x N, a novel charge neutralization method was employed and calibration curves were created using an O 2 + primary beam with positive secondary ion detection and a Cs + primary beam with negative and MCs + secondary ion detection. Over the range of 0 < x < 0.58, the matrix ion intensity ratios of Al + /Ga + and AlCs + /GaCs + appear linear with the mole fraction ratio x/(1-x), and the ratio of AlN - /GaN - is linear with AlN mole fraction (x). The sputter rate decreases as AlN mole fraction increases, while the relative sensitivity factors (RSF's) of impurities have an exponential relationship with AlN mole fraction. These calibration curves allow the quantification of both matrix and impurity species in AlGaN with varying AlN mole fraction. The technique can be employed for impurity control, composition and growth rate determination, as well as structural analysis of the finished optoelectronic and electronic devices.}, number={19}, journal={APPLIED SURFACE SCIENCE}, author={Gu, C. J. and Stevie, F. A. and Hitzman, C. J. and Saripalli, Y. N. and Johnson, M. and Griffis, D. P.}, year={2006}, month={Jul}, pages={7228–7231} }
 @article{sivasubramani_lee_kim_kim_gnade_wallace_edge_schlom_stevie_garcia_et al._2006, title={Thermal stability of lanthanum scandate dielectrics on Si(100)}, volume={89}, ISSN={["0003-6951"]}, DOI={10.1063/1.2405418}, abstractNote={The authors have examined the thermal stability of amorphous, molecular beam deposited lanthanum scandate dielectric thin films on top of Si (100) after a 1000°C, 10s rapid thermal anneal. After the anneal, crystallization of LaScO3 is observed. Excellent suppression of lanthanum and scandium diffusion into the substrate silicon is indicated by the back-side secondary ion mass spectrometry (SIMS) analyses. In contrast, front-side SIMS and high-resolution electron energy loss analyses of the amorphous Si∕LaScO3∕Si (100) stack indicated the outdiffusion of lanthanum and scandium into the silicon capping layer during the anneal.}, number={24}, journal={APPLIED PHYSICS LETTERS}, author={Sivasubramani, P. and Lee, T. H. and Kim, M. J. and Kim, J. and Gnade, B. E. and Wallace, R. M. and Edge, L. F. and Schlom, D. G. and Stevie, F. A. and Garcia, R. and et al.}, year={2006}, month={Dec} }
 @article{harton_stevie_ade_2005, title={Diffusion-controlled reactive coupling at polymer-polymer interfaces}, volume={38}, ISSN={["0024-9297"]}, DOI={10.1021/ma047421b}, abstractNote={Reactive coupling of an end-functionalized polymer A with another endor chain-functionalized polymer B at an A-B interface is technologically referred to as reactive compatibilization. It is a proven means by which to reduce interfacial tension and improve adhesion between domains in polymer blends.1 In reactive systems, whether small-molecule or macromolecular in nature, the two regimes that generally describe the ratelimiting mechanism of the reaction are classified as diffusionand reaction-controlled (DC and RC, respectively) regimes.2 A dimensionless Damkohler number (NDa) as defined below can be used to determine which regime dominates a particular reaction.3}, number={9}, journal={MACROMOLECULES}, author={Harton, SE and Stevie, FA and Ade, H}, year={2005}, month={May}, pages={3543–3546} }
 @article{pierce_adekore_davis_stevie_2005, title={Growth of dense ZnO films via MOVPE on GaN(0001) epilayers using a low/high-temperature sequence}, volume={277}, ISSN={["1873-5002"]}, DOI={10.1016/j.jcrysgro.2005.01.054}, abstractNote={Dense zinc oxide thin films have been achieved on GaN(0 0 0 1) epilayers via the repetition of an iterative sequence involving the growth at 480 °C of needles having a decreasing diameter as a function of height followed by the lateral growth from the sidewalls of these needles and coalescence of the growth fronts at 800 °C. Each sequence resulted in a contiguous layer having a thickness of approximately 200 nm. Diethylzinc and UHP oxygen were used as sources of zinc and atomic oxygen, respectively; UHP argon served as both the carrier and the diluent gas. The final growth surface of each densified film contained hexagonal depressions caused by growth among needles of different heights and growth pits that increased in number with an increase in film thickness. These microstructural features were manifest upon and affected the densities and magnitudes of similar features produced in subsequent layers. Triple-axis X-ray diffraction measurements revealed that the orientations of the crystallographic planes and directions within the films mimicked those of the underlying GaN substrate. Concentrations of carbon and hydrogen oscillated throughout the films due to their incorporation primarily within the lower and larger volumes of the needles during each low-temperature deposition of this microstructure.}, number={1-4}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Pierce, JM and Adekore, BT and Davis, RF and Stevie, FA}, year={2005}, month={Apr}, pages={345–351} }
 @article{pierce_adekore_davis_stevie_2005, title={Homoepitaxial growth of dense ZnO(0001) and ZnO (1120) films via MOVPE on selected ZnO substrates}, volume={283}, number={02-Jan}, journal={Journal of Crystal Growth}, author={Pierce, J. M. and Adekore, B. T. and Davis, R. F. and Stevie, F. A.}, year={2005}, pages={147–155} }
 @book{giannuzzi_stevie_2005, title={Introduction to focused ion beams: Instrumentation, theory, techniques, and practice}, ISBN={0387231161}, publisher={New York: Springer}, author={Giannuzzi, L. A. and Stevie, F. A.}, year={2005} }
 @article{harton_koga_stevie_araki_ade_2005, title={Investigation of blend miscibility of a ternary PS/PCHMA/PMMA system using SIMS and mean-field theory}, volume={38}, ISSN={["1520-5835"]}, DOI={10.1021/ma051595r}, abstractNote={Poly(cyclohexyl methacrylate) (PCHMA) and polystyrene (PS) are miscible with each other, but each is highly immiscible with PMMA. Identifiable by the asymmetries in the binary mean-field interaction parameters χ, PS preferentially segregates to the PCHMA/PMMA interface. Secondary ion mass spectrometry was used to provide real-space depth profiles of deuterated PS (dPS) in a miscible blend with PCHMA. The initial dPS concentration was varied from 5 to 20% (v/v), and the blend film was annealed at 150 °C on a film of PMMA for 42 h. X-ray reflectometry was used to determine the interfacial width between PCHMA and PMMA at 150 °C. Using self-consistent mean-field theory, good agreement was found between the experimental and theoretical interfacial excess Z* of dPS at each concentration. Because of their similar glass transition temperatures (∼100 °C for PS and PCHMA) and the ability of PS and PCHMA to be controllably synthesized with low polydispersities, we anticipate this blend to be a model system for futur...}, number={25}, journal={MACROMOLECULES}, author={Harton, SE and Koga, T and Stevie, FA and Araki, T and Ade, H}, year={2005}, month={Dec}, pages={10511–10515} }
 @article{harton_stevie_spontak_koga_rafailovich_sokolov_ade_2005, title={Low-temperature reactive coupling at polymer–polymer interfaces facilitated by supercritical CO2}, volume={46}, ISSN={0032-3861}, url={http://dx.doi.org/10.1016/j.polymer.2005.07.085}, DOI={10.1016/j.polymer.2005.07.085}, abstractNote={Supercritical CO2 (scCO2) has been used to facilitate reactions in thin film bilayers between functionalized polystyrene and poly(methyl methacrylate) at temperatures far below the glass transition temperatures of the respective polymers. Secondary ion mass spectrometry (SIMS) is used to monitor the reaction progression directly by measuring the interfacial excess of deuterated PS. Complementary X-ray reflectometry (XR) yields the interfacial width and surface roughness of bilayer films for reactive systems with and without the addition of scCO2, and comparisons are made with unreactive reference systems. From XR and SIMS analyses, the interfacial width and roughness have been found to be effectively independent of the reaction conditions employed here, and the primary impact of incorporated scCO2 is enhanced mobility of the reactive polymer chains. The use of scCO2 can change polymer mobility significantly enough over a very small temperature range (DTw15 8C) so that both diffusion- and reaction-controlled type behavior can be observed for otherwise identical systems. q 2005 Elsevier Ltd. All rights reserved.}, number={23}, journal={Polymer}, publisher={Elsevier BV}, author={Harton, S.E. and Stevie, F.A. and Spontak, R.J. and Koga, T. and Rafailovich, M.H. and Sokolov, J.C. and Ade, H.}, year={2005}, month={Nov}, pages={10173–10179} }
 @article{stoddard_duscher_karoui_stevie_rozgonyi_2005, title={Segregation and enhanced diffusion of nitrogen in silicon induced by low energy ion bombardment}, volume={97}, ISSN={["1089-7550"]}, DOI={10.1063/1.1866480}, abstractNote={A sample of nitrogen-doped, single crystal Czochralski silicon was subjected to several different surface preparations. Secondary ion mass spectrometry depth profiling has shown that prolonged glancing-angle bombardment by 3–5kV Ar+ ions significantly increases the nitrogen concentration in the near surface by up to an order of magnitude over the bulk value. Concentrations are observed to be elevated over the bulk value to a depth up to 25μm. Nitrogen-implanted samples and samples with a 1nm surface nitride did not exhibit nitrogen segregation under the same conditions, but a sample with 100nm of surface nitride did exhibit ion bombardment induced drive-in. In nitride-free samples, the source of the nitrogen is indicated to be a nitrogen-rich layer in the first micron of material. The diffusion behavior of nitrogen in silicon is discussed and the Crowdion mechanism for diffusion is suggested as the enabling mechanism for the enhanced low temperature diffusion.}, number={8}, journal={JOURNAL OF APPLIED PHYSICS}, author={Stoddard, N and Duscher, G and Karoui, A and Stevie, F and Rozgonyi, G}, year={2005}, month={Apr} }
 @article{zhang_stevie_vanfleet_neelakantan_klimov_zhou_chow_2004, title={Diffusion profiles of high dosage Cr and V ions implanted into silicon}, volume={96}, ISSN={["1089-7550"]}, DOI={10.1063/1.1756221}, abstractNote={The depth profiles of high dosage 52Cr+ and 51V+ ions implanted in (100) crystalline silicon after thermal anneal at temperatures between 300 °C and 1000 °C are studied by secondary ion mass spectrometry and cross-sectional transmission electron microscopy. At dosages of 1×1015 ions/cm2 and above, the surface layer of silicon substrate is amorphorized. During the subsequent thermal annealing, the depth profiles of the implanted ions are strongly coupled with the solid phase epitaxial growth of amorphous silicon. Silicide precipitate formation is important to understand the differences between Cr and V diffusion. After anneal of the 1×1015 ions/cm2 implanted samples at 900 °C and 1000 °C, most of the Cr has left the silicon, but only 10% of the V has escaped. The 1×1014 ions/cm2 Cr-implanted sample shows Cr ions exist only near the surface after 1000 °C anneal. The V-implanted sample, on the other hand, only shows a narrowing of the V profile after 1000 °C anneal.}, number={2}, journal={JOURNAL OF APPLIED PHYSICS}, author={Zhang, P and Stevie, F and Vanfleet, R and Neelakantan, R and Klimov, M and Zhou, D and Chow, L}, year={2004}, month={Jul}, pages={1053–1058} }
 @article{pivovarov_stevie_griffis_2004, title={Improved charge neutralization method for depth profiling of bulk insulators using O-2(+) primary beam on a magnetic sector SIMS instrument}, volume={231}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2004.03.070}, abstractNote={Use of electrons for charge neutralization during positive secondary ion SIMS analysis of insulators has typically been achieved using coincident primary ion and electron beams. The normal incidence electron gun on CAMECA magnetic sector SIMS instruments can effectively eliminate sample charging during analysis of thin insulating films if the electron energy is sufficient to penetrate the film. However, positive secondary ion SIMS bulk insulator analysis using this instrument can be difficult, especially if high sputtering rates are required. A neutralization method has been developed utilizing electron beam impact of a region adjacent to the sputtered area. Prior to analysis, the surface of the sample is coated with gold which provides a conductive surface layer and which has a high secondary and backscattered electron yield. Results have been obtained showing excellent neutralization for a variety of bulk insulators including glass, silica, alumina, and lithium niobate. Sputtering rates exceeding 2 nm/s have been achieved in bulk silica. The technique should be applicable to minerals and possibly for other materials in cases where the analyzed area cannot be directly irradiated with an electron beam.}, journal={APPLIED SURFACE SCIENCE}, author={Pivovarov, AL and Stevie, FA and Griffis, DP}, year={2004}, month={Jun}, pages={786–790} }
 @article{kachan_hunter_kouzminov_pivovarov_gu_stevie_griffis_2004, title={O-2(+) versus Cs+ for high depth resolution depth profiling of III-V nitride-based semiconductor devices}, volume={231}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2004.03.211}, abstractNote={Abstract Optimum depth resolution with adequate sensitivity for the elements of interest is required to obtain the information desired from SIMS analysis of multilayer nitride III–V structures. For many of the species of interest, particularly the p-type dopants, O2+ bombardment at low energy is often used. Use of Cs+ bombardment and detection of the cesium attachment secondary ions (CsM+ where M is the element of interest) may provide several advantages over O2+ analysis. Using similar low primary ion impact energy analysis conditions for O2+ and Cs+ on CAMECA IMS-6f and IMS-4f instruments, the depth resolution obtained for positive secondary ions is compared.}, journal={APPLIED SURFACE SCIENCE}, author={Kachan, M and Hunter, J and Kouzminov, D and Pivovarov, A and Gu, J and Stevie, F and Griffis, D}, year={2004}, month={Jun}, pages={684–687} }
 @article{gu_pivovarov_garcia_stevie_griffis_moran_kulig_richards_2004, title={Secondary ion mass spectrometry backside analysis of barrier layers for copper diffusion}, volume={22}, ISSN={["1071-1023"]}, DOI={10.1116/1.1617278}, abstractNote={Secondary ion mass spectrometry (SIMS) backside analyses have been performed on a Cu/TaN/Ta/SiO2/Si structure to determine barrier effectiveness for Cu diffusion. Sample backside access to the barrier layers was obtained by removal of the Si substrate using a polishing method that maintains parallelism between the sample surface and the polished back side by monitoring changes in facets at the four corners of the specimen. Determination of the Si thickness remaining during the polishing process was improved through the use of optical interference measurements using a narrow band pass optical filter. Samples having slopes with respect to the original surface less than 6 nm over 60 μm have been obtained. A difference in polishing rate between SiO2 and Si was exploited to obtain this parallelism. For SIMS analyses, the presence of a SiO2 layer required electron gun charge neutralization for the O2+ 0.5 keV impact energy analysis. SIMS analyses show the ability to distinguish all layers and to monitor copper ...}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Gu, C and Pivovarov, A and Garcia, R and Stevie, F and Griffis, D and Moran, J and Kulig, L and Richards, JF}, year={2004}, pages={350–354} }
 @article{gu_garcia_pivovarov_stevie_griffis_2004, title={Site-specific SIMS backside analysis}, volume={231}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2004.03.140}, abstractNote={For maximum SIMS depth resolution for any layer in a sample, the depth profile should begin only as far from the layer as necessary to establish a constant implant concentration of the primary ion beam species. Depth resolution and detection limit can be severely degraded if it is necessary to sputter through an over layer having non uniform sputtering properties or containing a high level of the impurity of interest prior to reaching the layer of interest. A SIMS backside analysis method based on mechanical polishing is extended to allow site-specific SIMS backside depth profile analysis. Optical microscopy employing a red filter was used to allow direct viewing of the site to be depth profiled both during polishing and in situ during SIMS analysis. Depth profile analyses were performed on 100μm×100 μm device test structures. Sample charging resulting from insulator layers present in these device test structures was alleviated using a modified sample mounting technique. Backside SIMS depth profile analysis using an O2+ primary ion beam having an impact energy of 1.25 keV was used to determine if boron had penetrated a thin SiO2 layer.}, journal={APPLIED SURFACE SCIENCE}, publisher={Elsevier BV}, author={Gu, C and Garcia, R and Pivovarov, A and Stevie, F and Griffis, D}, year={2004}, month={Jun}, pages={663–667} }
 @article{hunter_schueler_stevie_2004, title={Special Issue - Secondary Ion Mass Spectrometry SIMS XIV - Proceedings of the Fourteenth International Conference on Secondary Ion Mass Spectrometry and Related Topics - San Diego, California, USA, September 14-19, 2003 - Preface}, volume={231}, ISSN={["0169-4332"]}, DOI={10.1016/j.apsusc.2004.03.206}, journal={APPLIED SURFACE SCIENCE}, author={Hunter, J and Schueler, BW and Stevie, FA}, year={2004}, month={Jun}, pages={1–2} }
 @article{pivovarov_gu_stevie_griffis_2004, title={Utilization of electron impact ionization of gaseous and sputtered species in the secondary ion acceleration region of a magnetic sector SIMS instrument}, volume={231}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2004.03.069}, abstractNote={Negative secondary ion insulator analysis using a normal incidence electron gun (NEG) on CAMECA magnetic sector SIMS instruments can be difficult due to an inability to adequately determine the electron beam impact region during NEG alignment. The electron impact energy is too low to utilize phosphor cathodoluminescent materials that can be used for NEG alignment for positive secondary ion analyses. Detection of electron beam desorbed H− is often used for NEG alignment, but the presence of H on the surface is not always uniform and it is transient, making it difficult to determine whether variations in the H− secondary ion intensity are due to non-uniformity of the electron beam or of the H on the sample. To overcome this difficulty, a new technique has been developed that takes advantage of sputtering of the sample surface by positive ions created by electron impact ionization in the spectrometer secondary ion acceleration region between the sample and the immersion lens of the mass spectrometer. The formation of the ions occurs by interaction of residual gas species in the spectrometer secondary ion acceleration region with the NEG electron beam. This method is used to align the NEG for negative secondary ion charge neutralization.}, journal={APPLIED SURFACE SCIENCE}, author={Pivovarov, A and Gu, C and Stevie, F and Griffis, D}, year={2004}, month={Jun}, pages={781–785} }
 @article{francois-saint-cyr_stevie_mckinley_elshot_chow_richardson_2003, title={Diffusion of 18 elements implanted into thermally grown SiO2}, volume={94}, ISSN={["0021-8979"]}, DOI={10.1063/1.1624487}, abstractNote={Diffusion data are presented for 18 elements implanted in SiO2 layers thermally grown on silicon and annealed at temperatures ranging from 300 to 1000 °C. Most species studied, (e.g., Be, B, Al, Sc, Ti, V, Zn, Ga, and Mo), showed negligible diffusion over the examined temperature range. In general, this study has shown that the diffusivity of dopants or impurities in SiO2 is significantly smaller than that in silicon. However we also observed that several elements (e.g., Rb and In) have a higher diffusivity in SiO2 than in Si. Because Ga and In are both used as sources for focused ion beam analyses, the lack of Ga diffusion and the movement of In in SiO2 is of interest.}, number={12}, journal={JOURNAL OF APPLIED PHYSICS}, author={Francois-Saint-Cyr, HG and Stevie, FA and McKinley, JM and Elshot, K and Chow, L and Richardson, KA}, year={2003}, month={Dec}, pages={7433–7439} }
 @article{pivovarov_stevie_griffis_guryanov_2003, title={Optimization of secondary ion mass spectrometry detection limit for N in SiC}, volume={21}, ISSN={["0734-2101"]}, DOI={10.1116/1.1595108}, abstractNote={Controlled changes in the Cs+ primary ion beam density and analytical expressions describing the sources (bulk concentration, memory effect, and adsorption of N from the residual vacuum) of secondary ion mass spectrometry analyte secondary ion intensities were used to determine the contributions to the N secondary ion intensity obtained during the analysis of trace levels of N in bulk SiC. This methodology allows the determination of N concentrations that can be substantially less than the apparent N secondary ion background intensity. It was shown that for the Cameca IMS-6F instrumental conditions used, memory effect is the main contributor to the N background signal. Taking into consideration the Cs+ beam diameter, the raster size, the diameter of the ion-extracted area, and the impurity secondary ion intensity, an optimized combination of primary ion beam current and raster size was determined that resulted in the best detection limit for N in bulk SiC. This detection limit for N in bulk SiC (∼6×1014 a...}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Pivovarov, AL and Stevie, FA and Griffis, DP and Guryanov, GM}, year={2003}, pages={1649–1654} }
 @article{santiesteban_mckinley_stevie_flatch_rodriguez_2002, title={In-fab techniques for baselining implant dose, contamination}, volume={45}, number={8}, journal={Solid State Technology}, author={Santiesteban, R. S. and McKinley, J. M. and Stevie, F. A. and Flatch, P. and Rodriguez, O.}, year={2002}, pages={63-} }
 @article{clark_jones_stevie_2002, title={Secondary ion mass spectrometry induced damage adjacent to analysis craters in silicon}, volume={20}, ISSN={["0734-2101"]}, DOI={10.1116/1.1497178}, abstractNote={Damage introduced by dynamic secondary ion mass spectrometry (SIMS) depth profiling is studied. A silicon sample with a boron marker layer was depth profiled by dynamic SIMS. After subsequent annealing at 750 °C for 30 min, the SIMS sample was reanalyzed by plan-view transmission electron microscope (PTEM) and SIMS. PTEM images showed the presence of interstitial defects near the original SIMS crater, and SIMS depth profiles of similar regions exhibited boron diffusivity enhancements. Excess interstitials were introduced into the Si surface up to 2 mm from the original 225 μm×225 μm crater. Both PTEM and SIMS results showed that the damage and its effects diminished with an increase in distance from the original crater.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Clark, MH and Jones, KS and Stevie, FA}, year={2002}, pages={1663–1666} }
 @article{schwarz_kempshall_giannuzzi_stevie_2002, title={Utilizing the SIMS technique in the study of grain boundary diffusion along twist grain boundaries in the Cu(Ni) system}, volume={50}, ISSN={["1359-6454"]}, DOI={10.1016/S1359-6454(02)00362-2}, abstractNote={The secondary ion mass spectrometry (SIMS) technique was used to study grain boundary diffusion along (100) twist grain boundaries in the Cu(Ni) system. Concentration profiles of Ni down Cu twist grain boundaries with nominal disorientation angles of 10°, 5 (36.87°), and 45°, were measured using the SIMS technique. The average activation energy for grain boundary diffusion, Qb, was found to be 245 ± 22, 140 ± 10, and 102 ± 15 kJ / mol, for the 10°, 5, and 45° twist grain boundaries, respectively. The average grain boundary diffusion pre-exponential term, sdDbo, was found to be 9.6 ± 1.24 × 10 9 , 1.1 ± 0.17 × 10 14 , and 1.3 ± 0.36 × 10 16 m 3 / s, for the 10°, 5, and 45° twist grain boundaries, respectively.}, number={20}, journal={ACTA MATERIALIA}, author={Schwarz, SM and Kempshall, BW and Giannuzzi, LA and Stevie, FA}, year={2002}, month={Dec}, pages={5079–5084} }
 @article{ferryman_fulghum_giannuzzi_stevie_2002, title={XPS analysis of FIB-milled Si}, volume={33}, ISSN={["0142-2421"]}, DOI={10.1002/sia.1448}, abstractNote={The development of focused ion beam (FIB) workstations with beam sizes <10 nm in diameter has initiated a revolution in the modification and characterization of materials on a nanoscale. Focused ion beams are now widely used to obtain site‐specific specimens for scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, but are being utilized also in connection with Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS). In order to understand the structure/property relationships of new materials, it is imperative that nano‐characterization techniques with site‐specific precision be available. In this work, x‐ray photoelectron spectroscopy and imaging are used to study the surface changes that occur due to FIB milling of Si(100). The FIB‐prepared specimen was analyzed ‘as received’ and after the specimen was stored at room temperature and in the atmosphere for 5 months. The XPS images were acquired to determine the distribution of Si4+ (SiO2) and Ga contamination on the Si0 surface. Small‐area XPS spectra of the Si FIB specimen were collected to evaluate the changes in SiO2 surface concentration. The XPS spectra were also extracted from areas ∼1 µm × 1 µm by exploiting the images‐to‐spectra approach to XPS analysis. This study demonstrates both the problems inherent in the analysis of small samples and the critical information that can be obtained from high spatial resolution XPS analysis. In this example, increased SiO2 was observed in the ‘aged’ sample relative to the ‘as‐received’ sample, and non‐uniform Ga contamination was detected. Copyright © 2002 John Wiley & Sons, Ltd.}, number={12}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Ferryman, AC and Fulghum, JE and Giannuzzi, LA and Stevie, FA}, year={2002}, month={Dec}, pages={907–913} }