Contents
Abstract ……….
Acknowledgement ………..
List of symbols……….………..
List of contents………..
Introduction………..
Chapter 1
GaAs Field Effect Transistor
1.1 Introduction……….
1.2 Crystalline structure of GaAs………
1.3 Properties of GaAs ………
1.4 Material preparation….………..
1.4.1 Bulk growth of substrate material………
1.4.2 Material for the conducting channel ………..
1.5 The Metal Semiconductor Field Effect transistors………..
1.5.1 General structure……….
1.5.2 Principe of MESFET operation……….
1. 5.3 DC characteristics………
1.5.4 Saturation characteristics………
Chapter 2
Deep Levels in GaAs
2.1 Introduction………..
2.2 Deep Level and their interaction with carriers………..
2.3 Generation Recombination processes……….….
2.4 Transient evolution of tapped carriers………..
2.5 Detailed Balance Principle………...
2.6 Deep Level Transient Spectroscopy technique ………
2.6.1 Principle of the technique ………
2.7 Traps in GaAs and Backgating……….
2.8 Backgating effect………..
vi
I ii iii Vi iX
1 1 2 2 2 3 4 4 4 5 8
11 12 13 15 17 17 18 23 24 26 26 26 29 31
2.8.1 Backgating effects in GaAs FETs………..
2.8.2 Reduction of backgating………..
2.9 Life time and relaxation semiconductors………..
2.9.1 Characteristics of relaxation material……….…
2.9.2 Recombinative Pinning………..…………
Chapter 3 Modelling
3.1 Introduction………..
3.2 The phenomenological Transport equation………..
3.3 Discretization of the device ……….
3.4 Numerical method of resolution………
3.5 The channel conductance and substrate current modelling………
Chapter 4
Results and Discussions
4.1 Introduction ………..
4.2 The conductance and substrate current in absence of traps………..
4.3 The effect of deep acceptors………
4.3.1 Temperature effect ………...
4.4 The effect of deep donors……….
4.4.1 Temperature effect ……….
4.5 The effect of donor traps in the presence of high density of acceptor traps……
4.6 The effect of acceptors traps in the presence of high density of donor traps……
4.7 The effect of energy level position……….
4.7.1 Donor traps……….………
4.7.2 Acceptor traps………..
4.8 Backgating with and without threshold………
4.8.1.1 The donors effect………..…
4.8.1.2 The effect of the energy level of the donor trap………..
4.8.2.1 The acceptors effect……….
4.8.2.2 The effect of the energy level of the acceptor trap………..
4.8.3 Temperature effect on the threshold voltage ………
vii
49 50 53 56 57 59 60 62 64 64 65 67 67 68 69 70 33 34 36 37 48
71 73 74 74 74 76 76 76 77
4.8.4 Channel-Substrate spacing effect on threshold voltage ………
4.9 GaAs as relaxation material……….……….
4.9.1 Introduction……….
4.9.2 Substrate current and the relaxation regime……….
4.10 The effect of substrate dopping………
4.10.1 The effect of acceptors………
4.10.2 The effect of donors………..
4.10.3 The effect of temperature ………..
Conclusion
Appendix A……….
Appendix B………..
References ………
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