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Title: ONLINE SIMULATION OF SILICON-GERMANIUM HETEROJUNCTION BIPOLAR TRANSITOR USING NANOHUB SIMULATOR
Authors: Damot, Tesfaye
Advisors: Prof. Dr. Gerald Higelin
Copyright: 2008
Date Added: 22-Oct-2008
Publisher: Addis Ababa University
Abstract: CONTENTS ACKNOWLEDGEMENTS …………………………………………………………….IV ABSTRACT …………………………………………………………………………….V LIST OF TABLES ……………………………………………………………………..IX LIST OF FIGURES …………………………………………………………………….X ACRONYMS ...…………………………………………………………………..XI 1. Introduction ……………………………………………………….1 1.1.Evolution of Bipolar Technology…………………………………………1 1.2.Heterojunction Bipolar Transistor ………………………………………..1 1.3.Development SiGe HBT Technology …………………………………….2 1.4.Motivation ………………………………………………………………...3 1.5.Thesis Organization ………………………………………………………4 2. Theory of SiGe HBTs ……………………………………………..5 2.1.Energy Band ……………………………………………………………...8 2.2.Terminal Currents in a SiGe HBT ………………………………………10 2.3.Transit Time ……………………………………………………………..17 2.4.Early Voltage……………………………………………………………..18 2.5.Heterojunction barrier Effects …………………………………………...20 2.6.High level injection ……………………………………………………...21 2.7.High frequency figure of merit …………………………………………..22 2.7.1. Unity gain cut-off frequency, fT ………………………………………...22 2.7.2. Maximum oscillation frequency, fmax …………………………………...24 6 2.8. Breakdown Voltage, BVCEO ……………………………………………25 3. Design of SiGe HBTs …………………………………………….27 3.1.Device Modeling ………………………………………………………...29 3.2.Numerical Methods ……………………………………………………...33 3.2.1. Numerical Solution Technique ………………………………………….33 3.2.2. Basic Drift Diffusion calculations ………………………………………34 3.2.3. Drift Diffusion calculations with Lattice Heating ………………………34 3.2.4. Energy Balance Calculations…………………………………………….34 3.2.5. Energy Balance Calculations with Lattice Heating……………………...35 3.3.Material Parameters for Simulation ……………………………………...36 3.3.1. SiGe: hole mobility………………………………………………………38 3.3.2. SiGe: electron mobility……………………………………………..........40 3.3.3. SiGe: bandgap……………………………………………………………42 3.3.4. Recombination and carrier life time……………………………………..44 3.4.Device Design issues……………………………………………………..45 3.4.1. Base design………………………………………………………….46 3.4.2. Emitter design……………………………………………………….46 3.4.3. Collector design……………………………………………………..47 4. The Device Simulator PADRE …………………………………..49 4.1.The PADRE syntax………………………………………………………49 4.2.Choice of the numerical method…………………………………………51 4.3. Solutions obtained…………………………………………………….....53 4.4. Advanced Solution Techniques……………………………………….....57 4.4.1. Obtaining Solution around Breakdown Voltage ………………………..57 4.4.2. Using current Boundary Conditions …………………………………….57 7 4.5. Plot and Log Statement …………………………………………………60 4.5.1. Plot Statement……………………………………………………………60 4.5.2. Log Statement……………………………………………………………64 5. Simulation Results and Discussion………………………………65 5.1. DC characteristics ……………………………………………………….65 6. Conclusion and Future work ……………………………………76 6.1.Summary ………………………………………………………………...76 6.2.Future Work ……………………………………………………………..76 Reference ……………………………………………………………77
Description: A thesis submitted to the School of Graduate Studies of Addis Ababa University in partial fulfillment of the Degree of Masters of Science in Electrical Engineering
URI: http://hdl.handle.net/123456789/1553
Appears in:Thesis - Electrical Engineering

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