@article{brummel_zhou_ihlefeld_2024, title={Effect of background gas composition on the stoichiometry and lithium ion conductivity of pulse laser deposited epitaxial lithium lanthanum tantalate (Li<sub>3<i>x</i></sub>La<sub>1/3-<i>x</i></sub>TaO<sub>3</sub>)}, volume={42}, ISSN={["1520-8559"]}, DOI={10.1116/6.0003457}, abstractNote={Lithium lanthanum tantalate (Li3xLa1/3−xTaO3, x = 0.075) thin films were grown via pulsed laser deposition using background gas atmospheres with varying partial pressures of oxygen and argon. The background gas composition was varied from 100% to 6.6% oxygen, with the pressure fixed at 150 mTorr. The maximum ion conductivity of 1.5 × 10−6 S/cm was found for the film deposited in 100% oxygen. The ion conductivity of the films was found to decrease with reduced oxygen content from 100% to 16.6% O2 in the background gas. The 6.6% oxygen background condition produced ion conductivity that approached that of the 100% oxygen condition film. The lithium transfer from the target to the film was found to decrease monotonically with decreasing oxygen content in the background gas but did not account for all changes in the ion conductivity. The activation energy of ion conduction was measured and found to correlate well with the measured ion conductivity trends. Analysis of x-ray diffraction results revealed that the films also exhibited a change in the lattice parameter that directly correlated with the ion conduction activation energy, indicating that a primary factor for determining the conductivity of these films is the changing size of the ion conduction bottleneck, which controls the activation energy of ion conduction.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Brummel, Ian A. and Zhou, Chuanzhen and Ihlefeld, Jon F.}, year={2024}, month={May} }
 @article{ramesh_davis_roros_zhou_he_gao_menegatti_khan_genzer_2022, title={Nonwoven Membranes with Infrared Light-Controlled Permeability}, volume={9}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.2c13280}, abstractNote={This study presents the development of the first composite nonwoven fiber mats (NWFs) with infrared light-controlled permeability. The membranes were prepared by coating polypropylene NWFs with a photothermal layer of poly(N-isopropylacrylamide) (PNIPAm)-based microgels impregnated with graphene oxide nanoparticles (GONPs). This design enables "photothermal smart-gating" using light dosage as remote control of the membrane's permeability to electrolytes. Upon exposure to infrared light, the GONPs trigger a rapid local increase in temperature, which contracts the PNIPAm-based microgels lodged in the pore space of the NWFs. The contraction of the microgels can be reverted by cooling from the surrounding aqueous environment. The efficient conversion of infrared light into localized heat by GONPs coupled with the phase transition of the microgels above the lower critical solution temperature (LCST) of PNIPAm provide effective control over the effective porosity, and thus the permeability, of the membrane. The material design parameters, namely the monomer composition of the microgels and the GONP-to-microgel ratio, enable tuning the permeability shift in response to IR light; control NWFs coated with GONP-free microgels displayed thermal responsiveness only, whereas native NWFs showed no smart-gating behavior at all. This technology shows potential toward processing temperature-sensitive bioactive ingredients or remote-controlled bioreactors.}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Ramesh, Srivatsan and Davis, Jack and Roros, Alexandra and Zhou, Chuanzhen and He, Nanfei and Gao, Wei and Menegatti, Stefano and Khan, Saad and Genzer, Jan}, year={2022}, month={Sep} }
 @article{alcala_richter_materano_lomenzo_zhou_jones_mikolajick_schroeder_2021, title={Influence of oxygen source on the ferroelectric properties of ALD grown Hf1-xZrxO2 films}, volume={54}, ISSN={["1361-6463"]}, DOI={10.1088/1361-6463/abbc98}, abstractNote={Hafnium oxide (HfO2), zirconium oxide (ZrO2), and the solid-solution (Hf1-xZrxO2) system continue to be some of the most relevant ferroelectric materials, in particular, for their promising application in CMOS integrated ferroelectric memories. Recent understanding of the influence of oxygen supplied during film deposition on the structural phase formation process in Hf1-xZrxO2 films has drawn attention to a commonly overlooked parameter for tuning ferroelectric and electrical properties of these films. In this paper, a comparison of O3 and O2 plasma used as the oxygen source in an atomic layer deposition process for Hf1-xZrxO2 films within the full compositional range is discussed. A combination of structural and electrical characterization methods grant insight on the influence of each of the oxygen sources on the crystalline phase formation during deposition of Hf1-xZrxO2 films. These observations are then correlated to the material’s behavior regarding its ferroelectric and electrical properties; mainly, dielectric constant, ferroelectric remanent polarization, and number of electric field cycles to breakdown.}, number={3}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Alcala, Ruben and Richter, Claudia and Materano, Monica and Lomenzo, Patrick D. and Zhou, Chuanzhen and Jones, Jacob L. and Mikolajick, Thomas and Schroeder, Uwe}, year={2021}, month={Jan} }
 @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{materano_mittmann_lomenzo_zhou_jones_falkowski_kersch_mikolajick_schroeder_2020, title={Influence of Oxygen Content on the Structure and Reliability of Ferroelectric HfxZr1-xO2 Layers}, volume={2}, ISSN={["2637-6113"]}, DOI={10.1021/acsaelm.0c00680}, abstractNote={Although some years have passed since the discovery of the ferroelectric phase in HfO2 and ZrO2 and their solid solution system HfxZr1–xO2, the details of the emergence of this phase are still unde...}, number={11}, journal={ACS APPLIED ELECTRONIC MATERIALS}, author={Materano, Monica and Mittmann, Terence and Lomenzo, Patrick D. and Zhou, Chuanzhen and Jones, Jacob L. and Falkowski, Max and Kersch, Alfred and Mikolajick, Thomas and Schroeder, Uwe}, year={2020}, month={Nov}, pages={3618–3626} }
 @article{hany_yang_zhou_sun_gundogdu_seyitliyev_danilov_castellano_sun_vetter_et al._2019, title={Low temperature cathodoluminescence study of Fe-doped β-Ga2O3}, volume={257}, ISSN={0167-577X}, url={http://dx.doi.org/10.1016/j.matlet.2019.126744}, DOI={10.1016/j.matlet.2019.126744}, abstractNote={Optical and electrical properties along the b-axis of Fe-doped β-Ga2O3 were studied using low temperature cathodoluminescence (CL) spectroscopy, optical absorption spectroscopy and current-voltage (IV) measurements. The optical absorption spectroscopy showed an absorption edge without near edge shoulder and the corresponding optical bandgap was calculated to be 4.45 eV using direct band gap treatment. The temperature dependent CL measurements exhibited a strong blue to ultraviolet (UV) band composed of multiple low intensity peaks in the blue range, a main blue peak, a main UV peak, and a weak UV band from the as-grown Fe-doped β-Ga2O3. After a controlled annealing in air, the emissions changed to a red to near infrared (R-NIR) band with two sharp peaks and an UV band that is resolved at room temperature to three UV broad peaks. The R-NIR sharp peaks from the air-annealed sample were ascribed to incorporation of nitrogen during air annealing.}, journal={Materials Letters}, publisher={Elsevier BV}, author={Hany, Ibrahim and Yang, Ge and Zhou, Chuanzhen Elaine and Sun, Cheng and Gundogdu, Kenan and Seyitliyev, Dovletgeldi and Danilov, Evgeny O. and Castellano, Felix N. and Sun, Dali and Vetter, Eric and et al.}, year={2019}, month={Dec}, pages={126744} }
 @article{zhang_yang_zhou_chung_hany_2019, title={Optical and electrical properties of all-inorganic Cs2AgBiBr6 double perovskite single crystals}, volume={9}, ISSN={["2046-2069"]}, url={https://doi.org/10.1039/C9RA04045E}, DOI={10.1039/c9ra04045e}, abstractNote={Temperature-dependent resistivity and cathodoluminescence (CL) measurements of solution-processed Cs2AgBiBr6 double perovskite single crystals.}, number={41}, journal={RSC ADVANCES}, publisher={Royal Society of Chemistry (RSC)}, author={Zhang, Zheng and Yang, Ge and Zhou, Chuanzhen and Chung, Ching-Chang and Hany, Ibrahim}, year={2019}, month={Aug}, pages={23459–23464} }
 @article{mittmann_materano_lomenzo_park_stolichnov_cavalieri_zhou_chung_jones_szyjka_et al._2019, title={Origin of Ferroelectric Phase in Undoped HfO2 Films Deposited by Sputtering}, volume={6}, ISSN={2196-7350 2196-7350}, url={http://dx.doi.org/10.1002/ADMI.201900042}, DOI={10.1002/admi.201900042}, abstractNote={Abstract}, number={11}, journal={Advanced Materials Interfaces}, publisher={Wiley}, author={Mittmann, Terence and Materano, Monica and Lomenzo, Patrick D. and Park, Min Hyuk and Stolichnov, Igor and Cavalieri, Matteo and Zhou, Chuanzhen and Chung, Ching‐Chang and Jones, Jacob L. and Szyjka, Thomas and et al.}, year={2019}, month={Jun}, pages={1900042} }
 @article{malur_mohan_barrington_leffler_malur_muller-borer_murray_kew_zhou_russell_et al._2019, title={Peroxisome Proliferator-activated Receptor-gamma Deficiency Exacerbates Fibrotic Response to Mycobacteria Peptide in Murine Sarcoidosis Model}, volume={61}, ISSN={["1535-4989"]}, DOI={10.1165/rcmb.2018-0346OC}, abstractNote={We established a murine model of multiwall carbon nanotube (MWCNT)-elicited chronic granulomatous disease which bears similarities to human sarcoidosis pathology including alveolar macrophage deficiency of peroxisome-proliferator-activated receptor gamma (PPARγ). Because lymphocyte reactivity to mycobacterial antigens has been reported in sarcoidosis, we hypothesized that addition of mycobacterial Early Secreted Antigenic Target Protein 6 (ESAT-6) to MWCNT might exacerbate pulmonary granulomatous pathology. MWCNT with or without ESAT-6 peptide-14 were instilled by oropharyngeal route into macrophage-specific PPARγ KO or wild-type mice. Controls received PBS or ESAT-6. Lung tissues, bronchoalveolar lavage (BAL) cells and fluid, were evaluated 60 days post instillation. PPARγ-KO mice receiving MWCNT+ESAT-6 had increased granulomas and significantly elevated fibrosis (trichrome staining) vs wild-type mice or PPARγ-KO mice receiving only MWCNT. Immunostaining of lung tissues noted elevated fibronectin and Siglec F expression on CD11c(+) infiltrating alveolar macrophages in the presence of MWCNT+ESAT-6 compared to MWCNT. Analyses of BALF proteins indicated increased levels of Transforming Growth Factor-β (TGF-β) and the TGF-β pathway mediator IL-13, in PPARγ-KO mice receiving MWCNT+ESAT-6 compared to wild-type or PPARγ KO receiving MWCNT. Similarly, mRNA levels of matrix metalloproteinase (MMP)-9, another requisite factor for TGF-β production, was elevated in PPARγKO by MWCNT+ESAT-6. Analysis of ESAT-6 in lung tissues by mass spectrometry revealed ESAT-6 retention in lung tissues of PPARγ-KO but not wild-type mice. Data indicate that PPARγ deficiency promotes pulmonary ESAT-6 retention, exacerbates macrophage responses to MWCNT+ESAT-6, and intensifies pulmonary fibrosis. Findings suggest that the model may facilitate understanding of the effects of environmental factors on sarcoidosis-associated pulmonary fibrosis.}, number={2}, journal={AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY}, author={Malur, Anagha and Mohan, Arjun and Barrington, Robert A. and Leffler, Nancy and Malur, Amrita and Muller-Borer, Barbara and Murray, Gina and Kew, Kim and Zhou, Chuanzhen and Russell, Josh and et al.}, year={2019}, month={Aug}, pages={198–208} }
 @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.}, 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.}, 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{schroeder_richter_park_schenk_pesic_hoffmann_fengler_pohl_rellinghaus_zhou_et al._2018, title={Lanthanum-Doped Hafnium Oxide: A Robust Ferroelectric Material}, volume={57}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.7b03149}, abstractNote={Recently simulation groups have reported the lanthanide series elements as the dopants that have the strongest effect on the stabilization of the ferroelectric non-centrosymmetric orthorhombic phase in hafnium oxide. This finding confirms experimental results for lanthanum and gadolinium showing the highest remanent polarization values of all hafnia-based ferroelectric films until now. However, no comprehensive overview that links structural properties to the electrical performance of the films in detail is available for lanthanide-doped hafnia. La:HfO2 appears to be a material with a broad window of process parameters, and accordingly, by optimization of the La content in the layer, it is possible to improve the performance of the material significantly. Variations of the La concentration leads to changes in the crystallographic structure in the bulk of the films and at the interfaces to the electrode materials, which impacts the spontaneous polarization, internal bias fields, and with this the field cycling behavior of the capacitor structure. Characterization results are compared to other dopants like Si, Al, and Gd to validate the advantages of the material in applications such as semiconductor memory devices.}, number={5}, journal={INORGANIC CHEMISTRY}, author={Schroeder, Uwe and Richter, Claudia and Park, Min Hyuk and Schenk, Tony and Pesic, Milan and Hoffmann, Michael and Fengler, Franz P. G. and Pohl, Darius and Rellinghaus, Bernd and Zhou, Chuanzhen and et al.}, year={2018}, month={Mar}, pages={2752–2765} }
 @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 insecticides permethrin and deltamethrin in mosquito netting, which is high density polyethylene, by ion implantation of chlorine and bromine, respectively [C. Zhou, F. A. Stevie, and S. C. Smith, J. Vac. Sci. Technol., B 34, 03H107 (2016) and C. Zhou, F. A. Stevie, and S. C. Smith, J. Vac. Sci. Technol., B 35, 031802 (2017)]. The authors have now explored extension of this method to a nitrogen containing an insect growth regulator, pyriproxyfen, by ion implantation of nitrogen. The species 12C14N− was monitored because of high secondary ion yield as opposed to negligible yield for N−. Initial results show that nitrogen can be quantified, but the detection limit is insufficient to monitor this compound. The ion implantation approach may be applicable to other materials, and the use of minor abundance isotopes, such as 15N and 18O, should also be considered.}, 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{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 implant. This is presumably due to the degradation of the polymer structure by the implant. Even with reduced chlorine implant dose, the ability to use the analysis of the standard to quantify chlorine in insecticide treated fiber with GCIB was limited because of secondary ion yield variations. Analysis of netting which was no longer effective against mosquitoes showed significantly less chlorine at the surface than fresh netting, similar to the results obtained with the Cs+ sputtering beam. The results are useful to understand the effectiveness of insecticide treated nets and have implications for the analysis of other organic materials with the use of ion implantation for quantification.}, 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{park_schenk_fancher_grimley_zhou_richter_lebeau_jones_mikolajick_schroeder_2017, title={A comprehensive study on the structural evolution of HfO2 thin films doped with various dopants}, volume={5}, ISSN={["2050-7534"]}, DOI={10.1039/c7tc01200d}, abstractNote={Quantitative phase analysis is first performed on doped Hafnia films to elucidate the structural origin of unexpected ferroelectricity.}, number={19}, journal={JOURNAL OF MATERIALS CHEMISTRY C}, author={Park, M. H. and Schenk, T. and Fancher, C. M. and Grimley, E. D. and Zhou, C. and Richter, C. and LeBeau, J. M. and Jones, J. L. and Mikolajick, T. and Schroeder, U.}, year={2017}, month={May}, pages={4677–4690} }
 @article{lomenzo_chung_zhou_jones_nishida_2017, title={Doped Hf0.5Zr0.5O2 for high efficiency integrated supercapacitors}, volume={110}, number={23}, journal={Applied Physics Letters}, author={Lomenzo, P. D. and Chung, C. C. and Zhou, C. Z. and Jones, J. L. and Nishida, T.}, year={2017} }
 @article{mangum_podowitz-thomas_nikkel_zhou_jones_2017, title={Investigating Pb diffusion across buried interfaces in Pb(Zr0.2Ti0.8)O-3 thin films via time-of-flight secondary ion mass spectrometry depth profiling}, volume={49}, ISSN={["1096-9918"]}, DOI={10.1002/sia.6255}, abstractNote={The diffusion of Pb through Pb(Zr0.2Ti0.8)O3(PZT)/Pt/Ti/SiO2/Si thin film heterostructures is studied by using time‐of‐flight secondary ion mass spectrometry depth profiling. The as‐deposited films initially contained 10 mol% Pb excess and were thermally processed at temperatures ranging from 325 to 700°C to promote Pb diffusion. The time‐of‐flight secondary ion mass spectrometry depth profiles show that increasing processing temperature promoted Pb diffusion from the PZT top film into the buried heterostructure layers. After processing at low temperatures (eg, 325°C), Pb+ counts were low in the Pt region. After processing at elevated temperatures (eg, 700°C), significant Pb+ counts were seen throughout the Pt layer and into the Ti and SiO2 layers. Intermediate processing temperatures (400, 475, and 500°C) resulted in Pb+ profiles consistent with this overall trend. Films processed at 400°C show a sharp peak in PtPb+ intensity at the PZT/Pt interface, consistent with prior reports of a Pt3Pb phase at this interface after processing at similar temperatures.}, number={10}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Mangum, John S. and Podowitz-Thomas, Stephen and Nikkel, Jason and Zhou, Chuanzhen and Jones, Jacob L.}, year={2017}, month={Oct}, pages={973–977} }
 @article{richter_schenk_park_tscharntke_grimley_lebeau_zhou_fancher_jones_mikolajick_et al._2017, title={Si doped hafnium oxide-a "fragile" ferroelectric system}, volume={3}, number={10}, journal={Advanced Electronic Materials}, author={Richter, C. and Schenk, T. and Park, M. H. and Tscharntke, F. A. and Grimley, E. D. and LeBeau, J. M. and Zhou, C. Z. and Fancher, C. M. and Jones, J. L. and Mikolajick, T. and et al.}, year={2017} }
 @article{zhou_beck_hinks_crawford_blake_2016, title={Advancing the Forensic Analysis of Dyed Fibers by Time-of-Flight Mass Spectrometry}, volume={3}, ISSN={["2330-5517"]}, DOI={10.14504/ajr.3.2.4}, abstractNote={Dyed fibers are commonly obtained as trace evidence at crime scenes. Time-of-flight mass spectrometry (TOF MS) has potential to substantially advance forensic dyed fiber analysis by providing “exact mass” data of dyes and other chemicals present in dyed fibers. Data from two approaches to using TOF MS for accurately identifying the molecular formula of dyes are reported. One involves extraction of dye from 100 μg or less of fiber followed by high performance liquid chromatography (HPLC-TOF MS) analysis. The other is time-of-flight secondary ion mass spectrometric (TOF SIMS) analysis of the surface and cross sections of dyed fibers without extraction. Both approaches can clearly identify commercially important dyes applied to polyester fibers. Key Terms Acid Dyes, Disperse Dyes, Forensics, HPLC, Mass Spectrometry, Polyester, SIMS, TOF}, number={2}, journal={AATCC JOURNAL OF RESEARCH}, author={Zhou, Chuanzhen and Beck, Keith R. and Hinks, David and Crawford, Anne and Blake, Samantha}, year={2016}, pages={25–32} }
 @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 netting fibers ranged from 4 × 1019 to 1.2 × 1020 atoms/cm3, which compares very well with the amount of insecticide put into the netting during fabrication. The results make possible the study of insecticide content at the surface and in the bulk of the netting. Investigation is in progress for the effect of washing mosquito nets on surface chlorine concentration.}, 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 compare the detection limit that can be obtained for various SIMS instrument configurations under typical operating conditions. Time of flight, magnetic sector, and quadrupole analyzers were used to analyze hydrogen and deuterium ion implanted silicon. The detection limits varied for the different analyzers used and were in the 1018–1019 atoms/cm3 range for hydrogen and as low as 1016 atoms/cm3 for deuterium.}, 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{scott_xue_wang_kline_hoffman_dougherty_zhou_bazan_brendan t. o'connor_2016, title={Significantly Increasing the Ductility of High Performance Polymer Semiconductors through Polymer Blending}, volume={8}, ISSN={["1944-8244"]}, DOI={10.1021/acsami.6b01852}, abstractNote={Polymer semiconductors based on donor-acceptor monomers have recently resulted in significant gains in field effect mobility in organic thin film transistors (OTFTs). These polymers incorporate fused aromatic rings and have been designed to have stiff planar backbones, resulting in strong intermolecular interactions, which subsequently result in stiff and brittle films. The complex synthesis typically required for these materials may also result in increased production costs. Thus, the development of methods to improve mechanical plasticity while lowering material consumption during fabrication will significantly improve opportunities for adoption in flexible and stretchable electronics. To achieve these goals, we consider blending a brittle donor-acceptor polymer, poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)-alt-[1,2,5]thiadiazolo[3,4-c]pyridine] (PCDTPT), with ductile poly(3-hexylthiophene). We found that the ductility of the blend films is significantly improved compared to that of neat PCDTPT films, and when the blend film is employed in an OTFT, the performance is largely maintained. The ability to maintain charge transport character is due to vertical segregation within the blend, while the improved ductility is due to intermixing of the polymers throughout the film thickness. Importantly, the application of large strains to the ductile films is shown to orient both polymers, which further increases charge carrier mobility. These results highlight a processing approach to achieve high performance polymer OTFTs that are electrically and mechanically optimized.}, number={22}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Scott, Joshua I. and Xue, Xiao and Wang, Ming and Kline, R. Joseph and Hoffman, Benjamin C. and Dougherty, Daniel and Zhou, Chuanzhen and Bazan, Guillermo and Brendan T. O'Connor}, year={2016}, month={Jun}, pages={14037–14045} }
 @article{lomenzo_takmeel_zhou_chung_moghaddam_jones_nishida_2015, title={Mixed Al and Si doping in ferroelectric HfO2 thin films}, volume={107}, number={24}, journal={Applied Physics Letters}, author={Lomenzo, P. D. and Takmeel, Q. and Zhou, C. Z. and Chung, C. C. and Moghaddam, S. and Jones, J. L. and Nishida, T.}, year={2015} }
 @article{lomenzo_takmeel_zhou_fancher_lambers_rudawski_jones_moghaddam_nishida_2015, title={TaN interface properties and electric field cycling effects on ferroelectric Si-doped HfO2 thin films}, volume={117}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.4916715}, DOI={10.1063/1.4916715}, abstractNote={Ferroelectric HfO2-based thin films, which can exhibit ferroelectric properties down to sub-10 nm thicknesses, are a promising candidate for emerging high density memory technologies. As the ferroelectric thickness continues to shrink, the electrode-ferroelectric interface properties play an increasingly important role. We investigate the TaN interface properties on 10 nm thick Si-doped HfO2 thin films fabricated in a TaN metal-ferroelectric-metal stack which exhibit highly asymmetric ferroelectric characteristics. To understand the asymmetric behavior of the ferroelectric characteristics of the Si-doped HfO2 thin films, the chemical interface properties of sputtered TaN bottom and top electrodes are probed with x-ray photoelectron spectroscopy. Ta-O bonds at the bottom electrode interface and a significant presence of Hf-N bonds at both electrode interfaces are identified. It is shown that the chemical heterogeneity of the bottom and top electrode interfaces gives rise to an internal electric field, which causes the as-grown ferroelectric domains to preferentially polarize to screen positively charged oxygen vacancies aggregated at the oxidized bottom electrode interface. Electric field cycling is shown to reduce the internal electric field with a concomitant increase in remanent polarization and decrease in relative permittivity. Through an analysis of pulsed transient switching currents, back-switching is observed in Si-doped HfO2 thin films with pinched hysteresis loops and is shown to be influenced by the internal electric field.}, number={13}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Lomenzo, Patrick D. and Takmeel, Qanit and Zhou, Chuanzhen and Fancher, Chris M. and Lambers, Eric and Rudawski, Nicholas G. and Jones, Jacob L. and Moghaddam, Saeed and Nishida, Toshikazu}, year={2015}, month={Apr}, pages={134105} }
 @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} }
 @inproceedings{chiuhuang_zhou_huang_2014, title={Exploring lithium-ion intensity and distribution via a time-of-flight secondary ion mass spectroscopy}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 10}, author={ChiuHuang, C. K. and Zhou, C. Z. and Huang, H. Y. S.}, year={2014} }
 @article{chiuhuang_zhou_huang_2014, title={In-situ imaging of lithium-ion batteries via the secondary ion mass spectrometry}, volume={5}, number={2}, journal={Journal of Nanotechnology in Engineering and Medicine}, author={ChiuHuang, C.-K. and Zhou, C. and Huang, H.-Y. S.}, year={2014} }
 @article{lomenzo_takmeel_zhou_liu_fancher_jones_moghaddam_nishida_2014, title={The effects of layering in ferroelectric Si-doped HfO2 thin films}, volume={105}, number={7}, journal={Applied Physics Letters}, author={Lomenzo, P. D. and Takmeel, Q. and Zhou, C. Z. and Liu, Y. and Fancher, C. M. and Jones, J. L. and Moghaddam, S. and Nishida, T.}, year={2014} }
 @inproceedings{chiuhuang_zhou_huang_2013, title={Exploring lithium-ion intensity and distribution via a Time-of-Flight Secondary Ion Mass Spectroscopy}, DOI={10.1115/imece2013-63013}, abstractNote={For high rate-capability and low cost lithium-ion batteries, the prevention of capacity loss is one of major challenges facing by lithium-ion batteries today. During electrochemical processes, lithium ions diffuse from and insert into battery electrodes accompanied with the phase transformation, where ionic diffusivity and concentration are keys to the resultant battery capacity. In the current study, we first compare voltage vs. capacity curves at different C-rates (1C, 2C, 6C, 10C). Second, lithium-ion distributions and intensity are quantified via the Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The result shows that voltage vs. capacity relations are C-rate dependent and larger hystereses are observed in the higher C-rate samples. Detailed quantification of lithium-ion intensity for the 1C sample is conducted. It is observed that lithium-ions are distributed uniformly inside the electrode. Therefore, the current study provides a qualitative and quantitative data to better understand C-rate dependent phenomenon of LiFePO4 battery cells.}, booktitle={ASME 2013 International Mechanical Engineering Congress & Exposition}, author={ChiuHuang, C.-K. and Zhou, C. and Huang, H.-Y. S.}, year={2013} }
 @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 redeposited Ga from sputtered or backsputtered particles emitted from the area under primary ion irradiation.}, 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{zhou_li_garcia_crawford_beck_hinks_griffis_2012, title={Time-of-Flight-Secondary Ion Mass Spectrometry Method Development for High-Sensitivity Analysis of Acid Dyes in Nylon Fibers}, volume={84}, ISSN={["1520-6882"]}, DOI={10.1021/ac3025569}, abstractNote={A minimally destructive technique for the determination of dyes in finished fibers provides an important tool for crime scene and other forensic investigations. The analytical power and the minimal sample consumption of time-of-flight-secondary ion mass spectrometric (TOF-SIMS) analysis provides the ability to obtain definitive molecular and elemental information relevant to fiber identification, including identification of dyes, from a very small volume of sample. For both fiber surface analysis and, with the aid of cryomicrotomy, fiber cross-section analysis, TOF-SIMS was used to identify various dyes in finished textile fibers. The analysis of C.I. Acid Blue 25 in nylon is presented as a representative example. The molecular ion of C.I. Acid Blue 25 with lower than 3% on weight-of-fiber (owf) dye loading cannot be identified on dyed nylon surfaces by TOF-SIMS using a Bi(3)(+) primary ion beam. Sputtering with C(60)(+) provided the ability to remove surface contamination as well as at least partially remove Bi-induced damage, resulting in a greatly improved signal-to-noise ratio for the Acid Blue 25 molecular ion. The use of C(60)(+) for damage removal in a cyclic manner along with Bi for data acquisition provided the ability to unambiguously identify Acid Blue 25 via its molecular ion at a concentration of 0.1% owf from both fiber surfaces and cross sections.}, number={22}, journal={ANALYTICAL CHEMISTRY}, author={Zhou, Chuanzhen and Li, Min and Garcia, Roberto and Crawford, Anne and Beck, Keith and Hinks, David and Griffis, Dieter P.}, year={2012}, month={Nov}, pages={10085–10090} }