The High Electron Mobility Transistor (HEMT) is a commonly used transistor for microwave and high power amplifiers around the world today. Typical application areas are space radio telescopes and cellular phones. Conventional HEMTs on today’s market use a Gallium,Arsenide (GaAs) substrate with an Aluminium, Gallium, Arsenide (AlGaAs) top layer; this old working horse has material limitations and scientists has pushed the GaAs material to its theoretical limit during the last50 years. New techniques and materials are required to keep up the development of today’s technological society…
Contents
1 INTRODUCTION
1.1 HISTORICAL VIEW
2 GROUP III-NITRIDES
2.1 INTRODUCTION
2.2 CRYSTAL STRUCTURE
2.3 TERNARY ALLOYS
2.4 DISLOCATIONS IN GROUP III – NITRIDES
2.5 POLARIZATION FIELDS
2.6 THERMAL AND ELECTRICAL PROPERTIES
3 CHEMICAL VAPOR DEPOSITION
3.1 INTRODUCTION
3.2 PROCESS PRINCIPLE
3.3 THE CVD REACTOR
3.4 PRECURSORS AND CARRIER GASES
3.5 THE CHOICE OF SUBSTRATE
3.6 SAPPHIRE (AL2O3)
AS SUBSTRATE
3.7 SILICON CARBIDE (SIC) AS SUBSTRATE
4 THE HIGH ELECTRON MOBILITY TRANSISTOR
4.1 INTRODUCTION
4.2 THE HEMT DEVICE AND THE OPERATION PRINCIPLE
4.3 THE TWO DIMENSIONAL ELECTRON GAS
4.4 THE ADVANTAGE OF GROUP III-NITRIDES FOR MICROWAVE POWER TECHNOLOGY
4.5 THE ALN EXCLUSION LAYER
4.6 THE DOUBLE HETEROJUNCTION
5 CHARACTERIZATION TECHNIQUES
5.1 CAPACITANCE-VOLTAGE (C-V)
5.2 RESISTIVITY MEASURMENTS
5.3 THICKNESS MAPPING
5.4 PHOTO LUMINESCENCE (PL)
6 ONE-DIMENSIONAL POISSON-SCHRÖDINGER SOLVER
6.1 FORMULATION OF THE PROBLEM
6.2 SOLVING THE PROBLEM (PSEUDO-CODE)
7 EXPERIMENTAL DETAILS
7.1 THE SUBSTRATE AND SAMPLE PREPARATION
7.2 GROWTH DETAILS
7.3 CHARACTERIZATION DETAILS
7.4 SIMULATION DETAILS
8 RESULTS AND DISCUSSION
8.1 INTRODUCTION
8.2 GROWN HEMT STRUCTURES
8.3 SH ALGAN-HEMT – RESULTS
8.4 SH ALGAN -HEMT WITH AN ALN EXCLUSION-LAYER – RESULTS
8.5 SH ALGAN-HEMT WITH AN AL0.07GA0.93N BUFFER LAYER – RESULTS
8.6 DH ALGAN-HEMT WITH AND WITHOUT AN ALN EXCLUSION-LAYER – RESULTS
8.7 BAND DIAGRAMS
8.8 DISCUSSION
9 CONCLUSIONS AND FUTURE WORK
10 APPENDIX A – THICKNESS MAPS
11 APPENDIX B – CHARCTERIZATION DATA
12 REFERENCES
Author: Lundskog, Anders
Source: Linköping University
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