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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Optical studies of calcium arsenide, heavily doped with phosphorus by ion-implantation.

January 1992 (has links)
by Mok Wing Keung. / Parallel title in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 149-154). / Acknowledgement --- p.i / Abstract --- p.ii / Table Of Contents --- p.iii / List Of Figures --- p.v / List Of Tables --- p.ix / List Of Plates --- p.x / Chapter Chapter One --- Introduction / Chapter 1.1 --- General introduction --- p.1 / Chapter 1.2 --- Gallium arsenide --- p.4 / Chapter 1.2.1 --- Basic facts --- p.4 / Chapter 1.2.2 --- Band structure --- p.6 / Chapter 1.2.3 --- Production of GaAs --- p.9 / Chapter 1.3 --- Ion implantation --- p.11 / Chapter 1.3.1 --- Principle of ion implantation --- p.11 / Chapter 1.3.2 --- Basic facts --- p.17 / Chapter 1.3.3 --- Radiation damage and annealing --- p.21 / Chapter 1.4 --- Optical measurements --- p.27 / Chapter 1.4.1 --- Basic facts --- p.27 / Chapter 1.4.2 --- Optical reflectance --- p.29 / Chapter 1.4.3 --- Oxide overlayer --- p.39 / Chapter Chapter Two --- Experimental / Chapter 2.1 --- Sample preparation --- p.42 / Chapter 2.2 --- Ion implantation --- p.46 / Chapter 2.2.1 --- Implantation parameters --- p.46 / Chapter 2.2.2 --- Computer modeling of implantation profiles --- p.48 / Chapter 2.3 --- Annealing --- p.57 / Chapter 2.3.1 --- Conventional annealing --- p.57 / Chapter 2.3.2 --- Rapid thermal annealing --- p.61 / Chapter 2.4 --- Optical reflectance measurement --- p.69 / Chapter 2.4.1 --- Principle of measurement --- p.69 / Chapter 2.4.1.1 --- Relative reflectance measurement --- p.71 / Chapter 2.4.1.2 --- Absolute reflectance measurement --- p.79 / Chapter 2.4.2 --- Error estimation and data reduction --- p.82 / Chapter 2.4.2.1 --- Error estimation --- p.84 / Chapter 2.4.2.2 --- Data reduction --- p.86 / Chapter 2.5 --- Optical microscopy and photoluminescence --- p.90 / Chapter Chapter Three --- Results And Discussion / Chapter 3.1 --- Surface morphology --- p.93 / Chapter 3.2 --- Optical reflectance measurement --- p.101 / Chapter 3.2.1 --- Reflectance spectrum --- p.101 / Chapter 3.2.1.1 --- Reference mirror --- p.101 / Chapter 3.2.1.2 --- Crystalline GaAs --- p.104 / Chapter 3.2.1.3 --- Implanted GaAs before annealing --- p.108 / Chapter 3.2.1.4 --- Conventional annealed GaAs --- p.115 / Chapter 3.2.1.5 --- Rapid thermal annealed GaAs (proximity) --- p.120 / Chapter 3.2.2 --- Extraction of optical constants --- p.128 / Chapter 3.2.2.1 --- Oxide overlayer --- p.128 / Chapter 3.2.2.2 --- Dielectric function --- p.132 / Chapter 3.3 --- Photoluminescence results --- p.143 / Chapter Chapter Four --- Conclusions And Suggestions For Further Work --- p.147 / References --- p.149
122

Optical waveguides in GaAs by MeV ion implantation.

January 1994 (has links)
by Choi Kup Sze. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references. / Acknowledgement / Abstract / Chapter 1. --- Introduction --- p.1-1 / Chapter 1.1 --- Introduction --- p.1-1 / Chapter 1.2 --- References --- p.1-6 / Chapter 2. --- Theory of Optical Waveguides --- p.2-1 / Chapter 2.1 --- Theory of Planar Slab Waveguides --- p.2-2 / Chapter 2.2 --- Theory of Channel Dielectric Waveguides --- p.2-13 / Chapter 2.2.1 --- Marcatili's Method --- p.2-13 / Chapter 2.2.2 --- Effective Index Method --- p.2-20 / Chapter 2.3 --- References --- p.2-24 / Chapter 3. --- A Numerical Method for Optical Waveguides --- p.3-1 / Chapter 3.1 --- Introduction --- p.3-1 / Chapter 3.2 --- two-dimensional Fourier Series Expansion Method --- p.3-2 / Chapter 3.3 --- References --- p.3-13 / Chapter 4. --- Theory of Directional Couplers --- p.4-1 / Chapter 4.1 --- Dual-Channel Coupler --- p.4-1 / Chapter 4.2 --- Multi-channel Directional Coupler --- p.4-8 / Chapter 4.3 --- References --- p.4-9 / Chapter 5. --- Waveguide Formation by Ion Implantation --- p.5-1 / Chapter 5.1 --- Introduction --- p.5-1 / Chapter 5.2 --- Physics of Ion Implantation --- p.5-3 / Chapter 5.3 --- Lattice Damage and Annealing --- p.5-5 / Chapter 5.3.1 --- Lattice Damage --- p.5-5 / Chapter 5.3.2 --- Annealing --- p.5-6 / Chapter 5.4 --- Index Change due to Implantation --- p.5-8 / Chapter 5.5 --- Waveguide Processing Techniques --- p.5-10 / Chapter 5.5.1 --- Photolithography --- p.5-10 / Chapter 5.5.2 --- Processing Techniques --- p.5-11 / Chapter 5.6 --- References --- p.5-13 / Chapter 6. --- Optical Loss in Waveguides --- p.6-1 / Chapter 6.1 --- Loss Mechanisms in Optical Waveguides --- p.6-1 / Chapter 6.2 --- Principle of Propagation Loss Measurement --- p.6-4 / Chapter 6.2.1 --- Cut-back Method --- p.6-5 / Chapter 6.2.2 --- Scattering Light Method --- p.6-7 / Chapter 6.2.3 --- Fabry-Perot Interference Technique --- p.6-9 / Chapter 6.3 --- References --- p.6-16 / Chapter 7. --- Fabrication and Measurement of Optical Waveguides --- p.7-1 / Chapter 7.1 --- Fabrication of Optical Waveguides --- p.7-1 / Chapter 7.1.1 --- Fabrication of waveguides in GaAs by MeV oxygen ion implantation --- p.7-1 / Chapter 7.1.2 --- Waveguide End Facet Preparation --- p.7-4 / Chapter 7.2 --- Measurement of Optical Waveguides --- p.7-7 / Chapter 7.2.1 --- Laser Sources --- p.7-7 / Chapter 7.2.2 --- Guided Wave Excitation --- p.7-10 / Chapter 7.2.3 --- Intensity Profile Measurement --- p.7-17 / Chapter 7.2.4 --- Coupling Coefficient Measurement --- p.7-20 / Chapter 7.2.5 --- Propagation Loss Measurement --- p.7-25 / Chapter 7.3 --- References --- p.7-34 / Chapter 8. --- Results and Discussions --- p.8-1 / Chapter 8.1 --- Near Field Pattern Measurement --- p.8-1 / Chapter 8.2 --- Discussion on the Index Change of the Implanted GaAs --- p.8-5 / Chapter 8.3 --- Propagation Loss Measurement --- p.8-8 / Chapter 8.4 --- Observation of Optical Coupling in Directional Coupler --- p.8-14 / Chapter 8.5 --- References --- p.8-19 / Chapter 9. --- Conclusion --- p.9-1 / Chapter 10. --- Improvement and Extension --- p.10-1 / Appendix 1 Evaluation of the product〈n2 φuvφu'v'〉 --- p.A1-1 / Appendix 2 Transmission of Lossy Fabry-Perot Cavity --- p.A2-1 / Appendix 3 Effective Index versus Index Difference --- p.A3-1 / Appendix 4 Effect of Temperature on the Transmission of a Fabry-Perot Cavity --- p.A4-1 / Appendix 5 Evaluation of An from the Near Field Pattern --- p.A5-1
123

Characterisation and crystal growth of GaAs and AlxGa1-xAs epilayers on [100] GaAs by liquid phase epitaxy (LPE).

January 1994 (has links)
by Clive Hau Ming Shiu. / On t.p., "x" and "1-x" are subscript. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves [126]-[130]). / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / TABLE OF CONTENTS --- p.iii / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter Chapter 2 --- THEORY --- p.3 / Chapter 2.1 --- Fundamentals of GaAs and AlGaAs --- p.3 / Chapter 2.1.1 --- Crystal structure and properties of GaAs --- p.4 / Chapter 2.1.2 --- General properties of GaAs at 300K --- p.5 / Chapter 2.1.3 --- Temperature dependence of bandgap for GaAs --- p.6 / Chapter 2.1.4 --- Dopants of GaAs --- p.7 / Chapter 2.1.5 --- Properties of AlGaAs --- p.8 / Chapter 2.2 --- Phase Equilibrium of GaAs and AlGaAs --- p.10 / Chapter 2.2.1 --- Phase diagram of Ga-As binary system --- p.11 / Chapter 2.2.2 --- Phase diagram of Al-Ga-As ternary system --- p.13 / Chapter 2.3 --- Principle of LPE growth --- p.17 / Chapter 2.3.1 --- General concept of liquid phase epitaxy --- p.17 / Chapter 2.3.2 --- Fundamental methods of LPE growth --- p.19 / Chapter 2.4 --- Dopants in GaAs and AlGaAs system --- p.21 / Chapter 2.4.1 --- Common dopants in GaAs --- p.22 / Chapter 2.4.2 --- Tellurium in GaAs --- p.23 / Chapter 2.4.3 --- Silicon in GaAs --- p.24 / Chapter 2.4.4 --- Tellurium and Tin in AlGaAs --- p.26 / Chapter Chapter 3 --- LPE SYSTEM FOR GaAs AND AlGaAs --- p.28 / Chapter 3.1 --- Basic requirements for horizontal sliding LPE system --- p.30 / Chapter 3.2 --- Cleaning process of the LPE system --- p.37 / Chapter 3.2.1 --- Cleaning procedures of the quartz parts --- p.37 / Chapter 3.2.2 --- Cleaning procedures of the stainless steel tubing --- p.38 / Chapter 3.2.3 --- Cleaning procedures of the graphite boat --- p.39 / Chapter 3.3 --- Final examination for LPE growth --- p.41 / Chapter 3.3.1 --- Examining the sealing of the system --- p.41 / Chapter 3.3.2 --- Examining the palladium hydrogen purifier --- p.41 / Chapter 3.3.2.1 --- Measuring the dew point --- p.41 / Chapter 3.3.2.2 --- Measuring the content of oxygen and nitrogen --- p.42 / Chapter 3.3.3 --- Adjusting and measuring the isothermal zone in the fumace --- p.42 / Chapter 3.3.4 --- Measuring of background impurity --- p.43 / Chapter 3.3.5 --- Inspection of the operating chamber --- p.44 / Chapter Chapter 4 --- EXPERIMENTALS --- p.45 / Chapter 4.1 --- Determination of GaAs and AlGaAs content in the source melt --- p.45 / Chapter 4.2 --- Calculation of GaAs and AlGaAs content in the source melt --- p.45 / Chapter 4.3 --- Experimental determination of source melt composition --- p.48 / Chapter 4.4 --- LPE growth method --- p.49 / Chapter 4.5 --- Thickness control of LPE epilayers --- p.49 / Chapter 4.6 --- Experimental procedures --- p.50 / Chapter Chapter 5 --- RESULTS AND DISCUSSIONS --- p.63 / Chapter 5.1 --- Growth condition studies of GaAs --- p.63 / Chapter 5.1.1 --- Experimental --- p.63 / Chapter 5.1.2 --- Phase equilibrium of GaAs in the range of 780 to 840 °C --- p.63 / Chapter 5.1.3 --- Results of undoped GaAs epilayers --- p.67 / Chapter 5.1.4 --- Results of Si doped GaAs epilayers --- p.72 / Chapter 5.2 --- Growth condition studies of AlxGa1-xAs for x=0.1 to 09 --- p.73 / Chapter 5.2.1 --- Phase equilibrium of AlxGa1-xAs for x=0.1 to 09 --- p.73 / Chapter 5.2.2 --- Relation between saturation of solution and he flatness of interface between epilayer and substrate --- p.79 / Chapter 5.2.3 --- Determination of composition x in AlxGa1-xAs --- p.82 / Chapter 5.2.4 --- Relation between epilayer thickness and x in AlxGa1-xAs --- p.84 / Chapter 5.3 --- High AlxGa1-xAs with x ´ 0.9 ° at 780 °C --- p.87 / Chapter 5.3.1 --- Deposition rate of high AlxGa1-xAs epilayer versus cooling rate --- p.87 / Chapter 5.3.2 --- Thickness profiles of epilayers versus cooling rate --- p.89 / Chapter 5.3.3 --- Spectroscopic refractive index of high AlxGa1-xAs in the visible light spectrum --- p.94 / Chapter 5.3.4 --- Rocking curves of high AlxGa1-xAs --- p.96 / Chapter 5.4 --- Tellurium doped AlxGa1-xAs with x ranging from 0.1 to 09 --- p.98 / Chapter 5.4.1 --- Carrier concentration versus composition x in AlxGa1-xAs --- p.98 / Chapter 5.4.2 --- Carrier concentration of Al0.3Ga0.7As versus Te mole fraction --- p.100 / Chapter 5.4.3 --- Donor activation energy of Te Versus x in AlxGa1-xAs --- p.102 / Chapter 5.4.4 --- Refractive index of Te doped AlxGa1-xAs at 300K --- p.105 / Chapter 5.4.5 --- Dependence of solubility upon Te doping level --- p.106 / Chapter 5.5 --- Heavily tellurium doped Al0.3Ga0.7As --- p.107 / Chapter 5.5.1 --- Diffractometry study of heavily Te doped Al0.3Ga0.7As --- p.108 / Chapter 5.5.2 --- Morphological studies and interface studies of heavily Te doped Al0.3Ga0.7As --- p.112 / Chapter Chapter 6 --- CONCLUSION --- p.119 / APPENDIX Photoluminance Analysis at room temperature / REFERENCE
124

Luminescent properties of zinc-blende ZnCdSe =: 閃鋅礦結構ZnCdSe的螢光性質. / 閃鋅礦結構ZnCdSe的螢光性質 / Luminescent properties of zinc-blende ZnCdSe =: Shan xin kuang jie gou ZnCdSe de ying guang xing zhi. / Shan xin kuang jie gou ZnCdSe de ying guang xing zhi

January 1996 (has links)
by Ng Po Yin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 57-59). / by Ng Po Yin. / Acknowledgments --- p.I / Abstract --- p.II / Table of contents --- p.III / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Interest in ZnxCd1-xSe/InP --- p.1 / Chapter 1.2 --- Our work --- p.2 / Chapter 1.3 --- Usefulness of PL --- p.4 / Chapter 1.4 --- Growth conditions of ZnSe/GaAs and ZnxCd1-x/InP --- p.4 / Chapter 1.5 --- Purposes of studying ZnSe/GaAs --- p.5 / Chapter 1.6 --- Inhomogeneity of ZnxCd1-xSe/InP --- p.5 / Chapter Chapter 2 --- Experimental setup and procedures --- p.7 / Chapter 2.1 --- Experimental setup --- p.7 / Chapter 2.2 --- Measurements performed --- p.10 / Chapter 2.3 --- Experimental procedures --- p.10 / Chapter Chapter 3 --- Results and discussion --- p.12 / Chapter 3.1 --- RT and 9K PL of ZnSe/GaAs --- p.12 / Chapter 3.2 --- "Excitation power density dependent, RT and 9K PL of ZnxCd1-xSe/InP" --- p.20 / Chapter 3.3 --- Temperature dependent PL of ZnSe/GaAs and ZnxCd1-xSe/InP --- p.45 / Chapter Chapter 4 --- Conclusions and future work --- p.55 / References --- p.57
125

Photoluminescence and X-ray diffraction studies of MOCVD grown GaAs₁₋̳xSb̳x hetero-structures and quantum wells. / 以光致發光譜和高解析度X射線衍射譜研究砷銻化鎵外延層和量子井 / Photoluminescence and X-ray diffraction studies of MOCVD grown GaAs₁₋̳xSb̳x hetero-structures and quantum wells. / Yi guang zhi fa guang pu he gao jie xi du X she xian yan she pu yan jiu shen ti hua jia wai yan ceng he liang zi jing

January 2003 (has links)
Iu Kwan Sai = 以光致發光譜和高解析度X射線衍射譜研究砷銻化鎵外延層和量子井 / 姚昀樨. / On t.p. "̳x" is subscript. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 93-95). / Text in English; abstracts in English and Chinese. / Iu Kwan Sai = Yi guang zhi fa guang pu he gao jie xi du X she xian yan she pu yan jiu shen ti hua jia wai yan ceng he liang zi jing / Yao Yunxi. / ACKNOWLEDGMENTS --- p.i / ABSTRACT --- p.ii / TABLE OF CONTENTS --- p.v / LIST OF TABLES --- p.vii / LIST OF FIGURES --- p.viii / Chapter 1. --- INTRODUTION --- p.1 / Chapter 1.1 --- Motivations --- p.1 / Chapter 1.2 --- Historical Works --- p.1 / Chapter 1.3 --- This Study --- p.3 / Chapter 1.4 --- Growth Conditions of GaAs1-xSbx Alloy --- p.4 / Chapter 2. --- EXPERIMENTAL PROCEDURES --- p.5 / Chapter 2.1 --- High Resolution X-Ray Diffraction (HRXRD) --- p.5 / Chapter 2.1.1 --- The Use of HRXRD --- p.5 / Chapter 2.1.2 --- Setup of the High Resolution X-Ray Diffractometer --- p.7 / Chapter 2.1.3 --- Types of Measurements --- p.8 / Chapter 2.2 --- Photoluminescence (PL) Spectrometer --- p.10 / Chapter 2.2.1 --- The Use of PL --- p.10 / Chapter 2.2.2 --- Setup of PL spectrometer --- p.10 / Chapter 2.2.3 --- types of Measurements --- p.13 / Chapter 3. --- CHARACTERIZATION --- p.14 / Chapter 3.1 --- High Resolution X-Ray Diffraction (HRXRD) --- p.14 / Chapter 3.1.1 --- Principal Scattering Geometries --- p.14 / Chapter 3.1.2 --- Strains in the Epitaxial Layer --- p.16 / Chapter 3.1.3 --- Lattice Parameter --- p.21 / Chapter 3.1.4 --- Sb Composition --- p.24 / Chapter 3.1.5 --- Determination of Thickness --- p.24 / Chapter 3.2 --- Photoluminescence (PL) --- p.25 / Chapter 3.2.1 --- Basic Theory of PL --- p.25 / Chapter 3.2.2 --- Strain and Temperature Effect --- p.26 / Chapter 3.2.3 --- Type I and Type II PL --- p.27 / Chapter 3.2.4 --- The Energy Gap of GaAs1-xSbx --- p.28 / Chapter 4. --- RESULTS AND DISCUSSION --- p.31 / Chapter 4.1 --- Direct Analysis of HRXRD Rocking Curves --- p.31 / Chapter 4.1.1 --- GaAs1-xSbx / GaAs Quantum Wells (QWs) --- p.31 / Chapter 4.1.2 --- GaAs1-xSbx /InP Epitaxial Layers --- p.42 / Chapter 4.2 --- Computer Simulation of HRXRD --- p.51 / Chapter 4.2.1 --- Simulation Theory --- p.51 / Chapter 4.2.2 --- Simulation of Rocking Curves --- p.51 / Chapter 4.3 --- Room Temperature PL of GAAs1-xSBx Quantum Wells and Epitaxial Layers --- p.66 / Chapter 4.4 --- Low Temperature (LT) PL of GAAs1-xSBx Quantum Wells and Epitaxial Layers --- p.75 / Chapter 4.5 --- Excitation Power Dependent (PD) PL of GAAs1-xSBx Quantum Wells and Epitaxial Layers --- p.78 / Chapter 4.6 --- Temperature Dependent (TD) PL of GAAs1-xSBx Quantum Wells and Epitaxial Layers --- p.85 / Chapter 5. --- CONCLUSIONS --- p.90 / REFERENCES --- p.93
126

Growth and characterization of gallium arsenide grown by conventional and current-controlled liquid phase epitaxy.

Gale, Ronald Paul January 1978 (has links)
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / Ph.D.
127

Growth and characterization of III-V compound semiconductor materials for use in novel MODFET structures and related devices

Schulte, Donald W. 27 November 1995 (has links)
Graduation date: 1996
128

Growth, fabrication and testing of pseudomorphic P-channel GaAs/InGaAs/AlGaAs MODFETS

Schulte, Donald W. 14 August 1992 (has links)
This thesis reports on the growth and characterization of p-type pseudomorphic A1GaAs /InGaAs /GaAs modulation doped field effect transistor (MODFET) structures. A series of different p-type MODFET structures were grown with a systematic variation of the indium mole fraction and quantum well width of the InGaAs channel region. Extensive characterization of these samples using van der Pauw Hall and photoluminescence measurements showed clear trends in carrier mobility and quantum well quality with respect to the structure of the InGaAs region. From this an optimal indium mole fraction and quantum well width were obtained. Subsequent to material characterization, MODFET devices were fabricated and characterized. The measured DC device performance was reasonable and suggests that high quality p-type MODFETS should be obtainable with a properly optimized device structure and fabrication process. / Graduation date: 1993
129

A P-well GaAs MESFET technology

Canfield, Philip C. 02 August 1990 (has links)
The semiconductor gallium arsenide (GaAs) has many potential advantages over the more widely used semiconductor silicon (Si). These include higher low field mobility, semi-insulating substrates, a direct band-gap, and greater radiation hardness. All these advantages offer distinct opportunities for implementation of new circuit functions or extension of the operating conditions of similar circuits in silicon based technology. However, full exploitation of these advantages has not been realized. This study examines the limitations imposed on conventional GaAs metal-semiconductor field effect transistor (MESFET) technology by deviations of the semi-insulating substrate material from ideal behavior. The interaction of the active device with defects in the semi-insulating GaAs substrate is examined and the resulting deviations in MESFET performance from ideal behavior are analyzed. A p-well MESFET technology is successfully implemented which acts to shield the active device from defects in the substrate. Improvements in the operating characteristics include elimination of drain current transients with long time constants, elimination of the frequency dependence of g[subscript ds] at low frequencies, and the elimination of sidegating. These results demonstrate that control of the channel to substrate junction results in a dramatic improvement in the functionality of the GaAs MESFET. The p-well MESFET RF characteristics are examined for different p-well doping levels. Performance comparable with the conventional GaAs MESFET technology is demonstrated. Results indicate that optimization of the p-well MESFET doping levels will result in devices with uniform characteristics from DC to the highest operating frequency. / Graduation date: 1991
130

Analysis and modeling of GaAs MESFET's for linear integrated circuit design

Lee, Mankoo 31 May 1990 (has links)
A complete Gallium Arsenide Metal Semiconconductor Field Effect Transistor (GaAs MESFET) model including deep-level trap effects has been developed, which is far more accurate than previous equivalent circuit models, for high-speed applications in linear integrated circuit design. A new self-backgating GaAs MESFET model, which can simulate low frequency anomalies, is presented by including deep-level trap effects which cause transconductance reduction and the output conductance and the saturation drain current to increase with the applied signal frequency. This model has been incorporated into PSPICE and includes a time dependent I-V curve model, a capacitance model, a subthreshold current model, an RC network describing the effective substrate-induced capacitance and resistance, and a switching resistance providing device symmetry. An analytical approach is used to derive capacitances which depend on Vgs and Vds and is one which also includes the channel/substrate junction modulation by the self backgating effect. A subthreshold current model is analytically derived by the mobile charge density from the parabolic potential distribution in the cut-off region. Sparameter errors between previous models and measured data in conventional GaAs MESFET's have been reduced by including a transit time delay in the transconductances, gm and gds, by the second order Bessel polynomial approximation. As a convenient extraction method, a new circuit configuration is also proposed for extracting simulated S-parameters which accurately predict measured data. Also, a large-signal GaAs MESFET model for performing nonlinear microwave circuit simulations is described. As a linear IC design vehicle for demonstrating the utility of the model, a 3-stage GaAs operational amplifier has been designed and also has been fabricated with results of a 35 dB open-loop gain at high frequencies and a 4 GHz gain bandwidth product by a conventional half micron MESFET technology. Using this new model, the low frequency anomalies of the GaAs amplifier such as a gain roll-off, a phase notch, and an output current lag are more accurately predicted than with any other previous model. This new self-backgating GaAs MESFET model, which provides accurate voltage dependent capacitances, frequency dependent output conductance, and transit time delay dependent transconductances, can be used to simulate low frequency effects in GaAs linear integrated circuit design. / Graduation date: 1991

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