TY - PAT TI - Method for water vapor enhanced charged-particle-beam machining AU - Russell, P. E. AU - Griffis, D. P. AU - Shedd, G. M. AU - Stark, T. J. AU - Vitarelli, J. C2 - 1999/// DA - 1999/// PY - 1999/// ER - TY - JOUR TI - Comparative study of field emission-scanning electron microscopy and atomic force microscopy to assess self-assembled monolayer coverage on any type of substrate AU - Neves, BRA AU - Salmon, ME AU - Russell, PE AU - Troughton, EB T2 - MICROSCOPY AND MICROANALYSIS AB - : In this work, we show how field emission-scanning electron microscopy (FE-SEM) can be a useful tool for the study of self-assembled monolayer systems. We have carried out a comparative study using FE-SEM and atomic force microscopy (AFM) to assess the morphology and coverage of self-assembled monolayers (SAM) on different substrates. The results show that FE-SEM images present the same qualitative information obtained by AFM images when the SAM is deposited on a smooth substrate (e.g., mica). Further experiments with rough substrates (e.g., Al grains on glass) show that FE-SEM is capable of unambiguously identifying SAMs on any type of substrate, whereas AFM has significant difficulties in identifying SAMs on rough surfaces. DA - 1999/// PY - 1999/// DO - 10.1017/S1431927699990475 VL - 5 IS - 6 SP - 413-419 SN - 1431-9276 KW - field emission-scanning electron microscopy KW - atomic force microscopy KW - scanning probe microscopy KW - self-assembled monolayers KW - octadecylphosphonic acid ER - TY - JOUR TI - Effects of oxygen on selective silicon deposition using disilane AU - PA O'Neil, AU - Ozturk, MC AU - Batchelor, AD AU - Maher, DM T2 - MATERIALS LETTERS AB - Using Si2H6 in an ultrahigh vacuum rapid thermal chemical vapor deposition reactor, we have investigated the role of high levels of oxygen (>5×10−6 Torr) introduced during selective silicon deposition. The effects of oxygen have been investigated with regard to oxygen incorporation, selectivity with respect to thermal SiO2, growth rate, and epitaxial quality. The addition of oxygen was found to enhance the inherent process selectivity of Si2H6 to SiO2 while causing no reduction in the silicon growth rate or measurable oxygen incorporation into the growing film for oxygen pressures below 5×10−5 Torr. Contrary to published reports, the silicon film was devoid of the pyramidal defects usually characteristic to highly oxygenated processes. The silicon surface morphology, however, exhibited increased roughness with increasing oxygen partial pressure. The surface roughness is believed to be a result of the high levels of oxygen adsorbed at the initial growth surface. DA - 1999/3// PY - 1999/3// DO - 10.1016/S0167-577X(98)00200-6 VL - 38 IS - 6 SP - 418-422 SN - 0167-577X KW - silicon KW - CVD KW - disilane KW - selective silicon deposition ER - TY - JOUR TI - Pendeo-epitaxy of gallium nitride thin films AU - Linthicum, K. J. AU - Gehrke, T. AU - Thomson, D. B. AU - Carlson, E. P. AU - Rajagopal, P. AU - Smith, T. AU - Batchelor, D. AU - Davis, R. T2 - Applied Physics Letters AB - Pendeoepitaxy, a form of selective lateral growth of GaN thin films has been developed using GaN/AlN/6H–SiC(0001) substrates and produced by organometallic vapor phase epitaxy. Selective lateral growth is forced to initiate from the (112̄0) GaN sidewalls of etched GaN seed forms by incorporating a silicon nitride seed mask and employing the SiC substrate as a pseudomask. Coalescence over and between the seed forms was achieved. Transmission electron microscopy revealed that all vertically threading defects stemming from the GaN/AlN and AlN/SiC interfaces are contained within the seed forms and a substantial reduction in the dislocation density of the laterally grown GaN. Atomic force microscopy analysis of the (112̄0) face of discrete pendeoepitaxial structures revealed a root mean square roughness of 0.98 Å. The pendeoepitaxial layer photoluminescence band edge emission peak was observed to be 3.454 eV and is blueshifted by 12 meV as compared to the GaN seed layer. DA - 1999/// PY - 1999/// DO - 10.1063/1.124317 VL - 75 IS - 2 SP - 196-198 ER - TY - JOUR TI - Observation of topography inversion in atomic force microscopy of self-assembled monolayers AU - Neves, BRA AU - Leonard, DN AU - Salmon, ME AU - Russell, PE AU - Troughton, EB T2 - NANOTECHNOLOGY AB - In this paper, we report on atomic force microscopy (AFM) investigation of a self-assembled monolayer (SAM) system - octadecylphosphonic acid (OPA) deposited on mica. With the deposition methods employed in this work, the SAM presents a partial coverage, i.e., the OPA covers only a fraction of the mica surface and, therefore, some bare mica regions are observed. Using standard intermittent contact AFM (IC-AFM) techniques (with medium to high oscillation damping), the topographic profile of this system clearly shows the flat SAM on top of the mica surface. However, when a small oscillation damping mode is employed, the topographic profile is inverted, i.e., the mica regions appear higher than the surrounding OPA layer. AFM experiments, carried out to assess the origin of this effect, yield strong evidences that it is related to the presence of a water contamination layer on the bare mica regions only. A semi-quantitative model is utilized to understand the experimental results. DA - 1999/12// PY - 1999/12// DO - 10.1088/0957-4484/10/4/307 VL - 10 IS - 4 SP - 399-404 SN - 0957-4484 ER - TY - JOUR TI - Quality of selective silicon epitaxial films deposited using disilane and chlorine AU - PA O'Neil, AU - Ozturk, MC AU - Batchelor, AD AU - Xu, MM AU - Maher, DM T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - We have previously reported on the selectivity and growth of a silicon epitaxy process using and in an ultrahigh‐vacuum rapid thermal chemical vapor deposition reactor. In this report, we have extended the previous work and provide information regarding the structural and electrical quality of thick (3000 Å) selective silicon epitaxial layers deposited under a variety of growth conditions. Electrical test structures, including enclosed n‐channel metal oxide semiconductor field effect transistors (MOSFETs) and large‐area gated diodes, were fabricated within the epitaxial layers. We demonstrate that variations in the chlorine to silicon ratio (Cl/Si) and the process temperature can lead to structural defects and low generation lifetimes. The defects, however, had a benign effect over the MOSFET drive current and channel transconductance. Overall, the results in this study indicate that high levels of chlorine, as well as low growth temperatures, can potentially inhibit the structural and/or electrical quality of selectively deposited silicon films. However, for growth at or above 800°C with a Cl/Si ratio of 0.23, excellent selectivity as well as extremely high bulk generation lifetimes can be obtained for films with structural defect densities well below the detection limits used within this study. © 1999 The Electrochemical Society. All rights reserved. DA - 1999/6// PY - 1999/6// DO - 10.1149/1.1391937 VL - 146 IS - 6 SP - 2337-2343 SN - 0013-4651 ER - TY - JOUR TI - Pendeo-epitaxy of gallium nitride and aluminum nitride films and heterostructures on silicon carbide substrate AU - Gehrke, T. AU - Linthicum, K. J. AU - Thomson, D. B. AU - Rajagopal, P. AU - Batchelor, A. D. AU - Davis, R. F. T2 - MRS Internet Journal of Nitride Semiconductor Research DA - 1999/// PY - 1999/// VL - 4S1 IS - G3.2 ER - TY - JOUR TI - Growth of selective silicon epitaxy using disilane and chlorine on heavily implanted substrates - II. Role of implanted arsenic AU - PA O'Neil, AU - Ozturk, MC AU - Batchelor, AD AU - Venables, D AU - Maher, DM T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - In this report, we present results on the low thermal budget deposition of selective silicon epitaxy on heavily arsenic implanted substrates using and in an ultrahigh vacuum rapid thermal chemical vapor deposition reactor. The selectivity of silicon to as well as the silicon growth kinetics, epitaxial quality, and dopant incorporation for varying substrate implant dose conditions and varying levels of chlorine during processing were investigated. We demonstrate that an increase in the arsenic implant dose can reduce the silicon growth by means of an inherent incubation time for deposition occurring in a chlorinated ambient. The extent to which the silicon growth suppression occurs, however, can be lessened by specific changes in the system conditions, and therefore, growth reductions due to arsenic can be minimized. In addition to changes in the silicon growth kinetics, arsenic implanted substrates have demonstrated a tendency to degrade the surface morphology and enhance the density of defects within the deposited silicon epitaxial films. Furthermore, by depositing the silicon film immediately following implantation and prior to any high temperature anneal, movement of arsenic into the deposited silicon layers has been observed at growth temperatures as low as 800°C. Therefore, the incorporation of arsenic into the deposited epitaxial films has been found to be controllable such that abrupt profiles or intentional diffuse structures can be achieved by variation of the process sequence and the annealing conditions. © 1999 The Electrochemical Society. All rights reserved. DA - 1999/8// PY - 1999/8// DO - 10.1149/1.1392053 VL - 146 IS - 8 SP - 3079-3086 SN - 0013-4651 ER - TY - JOUR TI - Growth of selective silicon epitaxy using disilane and chlorine on heavily implanted substrates - I. Role of implanted BF2 AU - PA O'Neil, AU - Ozturk, MC AU - Batchelor, AD AU - Venables, D AU - Xu, MM AU - Maher, DM T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - In this report, we present results on the low thermal budget deposition of selective silicon epitaxy on heavily implanted substrates using and , in an ultrahigh vacuum rapid thermal chemical vapor deposition reactor. Si growth kinetics, selectivity to , dopant incorporation, and epitaxial quality have been investigated for varying implant dose conditions and varying levels of chlorine during processing. Contrary to published reports, no significant selectivity degradation mechanism has been observed for oxides implanted, and therefore, damaged by ions. Additionally, with heavily implanted boron substrates no reduction in silicon growth occurred despite the presence of a hydrophilic substrate surface just prior to epitaxial growth. Although the hydrophilic surface did not affect the silicon growth rate, the epitaxial defect density did increase with increasing implant dose and chlorine flow rate during processing. The nature of these defects has been studied using atomic force microscopy and transmission electron microscopy. The incorporation of boron into the deposited epitaxial films has been investigated and abrupt profiles or intentionally diffuse structures were achieved through variation of the process sequence and annealing conditions. © 1999 The Electrochemical Society. All rights reserved. DA - 1999/8// PY - 1999/8// DO - 10.1149/1.1392052 VL - 146 IS - 8 SP - 3070-3078 SN - 0013-4651 ER - TY - JOUR TI - Effects of oxygen during selective silicon epitaxial growth using disilane and chlorine AU - PA O'Neil, AU - Ozturk, MC AU - Batchelor, AD AU - Xu, MM AU - Maher, DM T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - Using and in an ultrahigh‐vacuum rapid thermal chemical vapor deposition reactor, we have investigated the effects of oxygen introduced during selective silicon deposition for both chlorinated and nonchlorinated process chemistries. The effects of oxygen have been investigated with regard to oxygen incorporation, selectivity with respect to thermal , growth rate, and epitaxial structure. Initial studies have revealed that during silicon depositions from , the inherent selectivity of to is enhanced upon the addition of oxygen to the process ambient. Furthermore, using a nonchlorinated process chemistry, oxygen adsorbs predominantly at the epitaxy‐substrate interface and causes increased surface roughness. We have found, however, that the addition of chlorine can play a significant role in the passivation of the epitaxy‐substrate interface with oxygen and improves the resulting film's surface morphology. © 1999 The Electrochemical Society. All rights reserved. DA - 1999/6// PY - 1999/6// DO - 10.1149/1.1391938 VL - 146 IS - 6 SP - 2344-2352 SN - 0013-4651 ER - TY - JOUR TI - Relaxation phenomena in GaN/ AlN/ 6H-SiC heterostructures AU - Edwards, N. V. AU - Batchelor, A. D. AU - Buyanova, I. A. AU - Madsen, L. D. AU - Bremser, M. D. AU - Davis, R. F. AU - Aspnes, D. E. AU - Monemar, B. T2 - MRS Internet Journal of Nitride Semiconductor Research AB - We have developed a method to modulate the strain state (normally > 4 kbar, tensile) of moderately thick (∼2 μm) GaN based structures grown on 6H-SiC to a range 0 to -2 kbar of compressive stresses by introducing a strain-mediating layer (SML) above the standard high-temperature AlN buffer layer. The strain characteristics of subsequently deposited nitride layers can be modulated by changing the growth parameters of the SML layer. This is achieved by in-situ techiniques during crystal growth without degrading the optical and structural properties of the deposited layers. DA - 1999/// PY - 1999/// DO - 10.1557/s1092578300002830 VL - 4S1 IS - G3.78 ER - TY - JOUR TI - Identification of two patterns in magnetic force microscopy of shape memory alloys AU - Neves, BRA AU - Andrade, MS T2 - APPLIED PHYSICS LETTERS AB - In this work, we report on the observation of two coexisting patterns in magnetic force microscopy (MFM) images of shape memory alloys. The MFM signal of both patterns presents similar behavior with tip–surface separation. An investigation on the origin of these patterns presents strong evidence that both are of magnetic nature only and, furthermore, can be assigned as bulk and surface-related, respectively. DA - 1999/4/5/ PY - 1999/4/5/ DO - 10.1063/1.123767 VL - 74 IS - 14 SP - 2090-2092 SN - 0003-6951 ER -