Shuji Nakamura Stephen Pear ton
Gerhard Fasol
The Blue Laser Diode
The Complete Story
Second Updated and Extended Edition
With 256 Figures and 61 Tables
Springer
Contents
1. Introduction 1
1.1 LEDs and LDs 1
1.2 Group-Ill Nitride Compound Semiconductors 3
2. Background 7
2.1 Introduction 7
2.2 Applications and Markets for Gallium Nitride Light Emitting
Diodes (LEDs) and Lasers 7
2.3 Who Were the Early Key Players in the Field? 10
2.4 Why InGaN/AlGaN? '. 11
2.5 Key Steps in the Discovery - Materials Issues 13
2.5.1 Research History of Shuji Nakamura
and Selected Steps in the Development
of the Commercial Blue GaN LED 15
2.6 Why Did Nichia Succeed Where Many Much Larger
Multinationals and Research Groups Failed? 17
2.7 Additional Comments on Blue LED Research 20
2.8 A Short Summary of the Physics of Semiconductor Lasers
and LEDs 21
2.8.1 LEDs 23
2.8.2 Lasers 24
3. Physics of Gallium Nitride and Related Compounds 29
3.1 Introduction 29
3.2 Crystal Structures 29
3.2.1 Wurtzite versus Zincblende Structure 29
3.2.2 Growth of Wurtzite GaN onto Sapphire 31
3.2.3 Growth of Cubic (Zincblende) GaN 31
3.2.4 Growth of GaN onto Other Substrates 32
3.3 Electronic Band Structure 32
3.3.1 Fundamental Optical Transitions 34
3.3.2 Band Structure Near the Fundamental Gap 35
3.3.3 Band Parameters and Band Offsets for GaN, A1N,
and InN 36
XII Contents
3.4 Elastic Properties - Phonons 38
3.5 Other Properties of Gallium Nitride 38
3.5.1 Negative Electron Affinity (NEA) 41
3.5.2 Pyroelectricity 41
3.5.3 Transferred-Electron Effect (Gunn Effect) 41
3.6 Summary of Properties 42
4. GaN Growth 47
4.1 Growth Methods for Crystalline GaN 47
4.2 A New Two-Flow Metalorganic Chemical
Vapor Deposition System for GaN Growth (TF-MOCVD) . . . 48
4.3 In Situ Monitoring of GaN Growth Using Interference Effects 52
4.3.1 Introduction 52
4.3.2 Experimental Details 52
4.3.3 GaN Growth Without A1N Buffer Layer 54
4.3.4 GaN Growth with A1N Buffer Layer 59
4.3.5 Summary 65
4.4 Analysis of Real-Time Monitoring Using Interference Effects . 65
4.4.1 Introduction 65
4.4.2 Experimental Details 66
4.4.3 Results and Discussion 67
4.4.4 Summary 75
4.5 GaN Growth Using GaN Buffer Layer 75
4.5.1 Introduction 75
4.5.2 Experimental Details 75
4.5.3 Results and Discussion 76
4.6 In Situ Monitoring and Hall Measurements of GaN Growth
with GaN Buffer Layers 79
4.6.1 Introduction 79
4.6.2 Experimental Details 80
4.6.3 Results and Discussion 80
4.6.4 Summary 88
5. p-Type GaN Obtained by Electron Beam Irradiation 89
5.1 Highly p-Type Mg-Doped GaN Films Grown
with GaN Buffer Layers 89
5.1.1 Introduction 89
5.1.2 Experimental Details 89
5.1.3 Results and Discussion 90
5.2 High-Power GaN p-n Junction Blue Light Emitting Diodes . . 95
5.2.1 Introduction 95
5.2.2 Experimental Details 95
5.2.3 Results and Discussion 96
5.2.4 Summary 101
Contents XIII
6. n-Type GaN 103
6.1 Si- and Ge-Doped GaN Films Grown with GaN Buffer Layers 103
6.2 Experimental Details 104
6.3 Si Doping 104
6.4 Ge Doping 108
6.5 Mobility as a Function of the Carrier Concentration Ill
6.6 Summary 112
7. p-Type GaN 113
7.1 History of p-Type GaN Research 113
7.2 Thermal Annealing Effects on p-Type Mg-Doped GaN Films . 114
7.2.1 Introduction 114
7.2.2 Experimental Details 114
7.2.3 Results and Discussion 114
7.2.4 Appendix 119
7.3 Hole Compensation Mechanism of p-Type GaN Films 120
7.3.1 Introduction 120
7.3.2 Experimental Details 120
7.3.3 Results and Discussion: Explanation
of the Hole Compensation Mechanism of p-Type GaN . 121
7.3.4 Summary: Hydrogen Passivation and Annealing
of p-Type GaN 135
7.4 Properties and Effects of Hydrogen in GaN 136
7.4.1 Present State of Knowledge 137
7.4.2 Passivation 140
7.4.3 Hydrogen in As-Grown GaN 141
7.4.4 Diffusion of H in Implanted or Plasma-Treated GaN . . 145
7.4.5 Summary 147
8. InGaN 149
8.1 Introductory Remarks: The Role of Lattice Mismatch 149
8.2 High-Quality InGaN Films Grown on GaN Films 150
8.2.1 Introduction: InGaN on GaN 150
8.2.2 Experimental Details: InGaN on GaN 151
8.2.3 Results and Discussion: InGaN on GaN 151
8.2.4 Summary: InGaN on GaN 154
8.3 Si-Doped InGaN Films Grown on GaN Films 155
8.3.1 Introduction: Si-Doped InGaN on GaN 155
8.3.2 Experimental Details: Si-Doped InGaN on GaN 155
8.3.3 Results and Discussion: Si-Doped InGaN on GaN 155
8.3.4 Summary: Si-Doped InGaN on GaN 159
8.4 Cd-Doped InGaN Films Grown on GaN Films 160
8.4.1 Introduction: Cd-doped InGaN on GaN 160
8.4.2 Experimental Details 161
8.4.3 Results and Discussion 161
8.4.4 . Summary: Cd-Doped InGaN 166
XIV Contents
8.5 InxGai_xN/Irij/Gai_j/N Superlattices Grown on GaN Films . . 166
8.5.1 Introduction: lnxG&i-xN /lnyGai-yN Superlattices . . . 166
8.5.2 Experiments: In x Gai_ x N/In a Gai_ y N Superlattices . . . 167
8.5.3 Results and Discussion:
lnxG&i-xN/IriyGai^yN Superlattices 167
8.5.4 Summary: In^Gai^ajN/In^Gai-yN Superlattices 174
8.6 Growth of In^Gai-^N Compound Semiconductors
and High-Power InGaN/AlGaN Double Heterostructure
Violet Light Emitting Diodes 174
8.6.1 Introduction 174
8.6.2 Experimental Details 174
8.6.3 Growth and Properties
of InxGai_a;N Compound Semiconductors 177
8.6.4 High Power InGaN/AlGaN Double Heterostructure
Violet Light Emitting Diodes 181
8.6.5 Summary 183
8.7 p-GaN/n-InGaN/n-GaN Double-Heterostructure Blue Light
Emitting Diodes 184
8.7.1 Experimental Details 184
8.7.2 Results and Discussion 184
8.7.3 Summary 188
8.8 High-Power InGaN/GaN Double-Heterostructure Violet Light
Emitting Diodes 188
9. Zn and Si Co-Doped InGaN/AlGaN Double-Heterostructure
Blue and Blue-Green LEDs 193
9.1 Zn-Doped InGaN Growth and InGaN/AlGaN
Double-Heterostructure Blue Light Emitting Diodes 193
9.1.1 Introduction 193
9.1.2 Experimental Details 194
9.1.3 Zn-Doped InGaN 194
9.1.4 InGaN/AlGaN DH Blue LEDs 198
9.2 Candela-Class High-Brightness InGaN/AlGaN
Double-Heterostructure Blue Light Emitting Diodes 201
9.3 High-Brightness InGaN/AlGaN Double-Heterostructure
Blue-Green Light Emitting Diodes 203
9.4 A Bright Future for Blue-Green LEDs 207
9.4.1 Introduction 207
9.4.2 GaN Growth 209
9.4.3 InGaN 209
9.4.4 InGaN/AlGaN DH LED 209
9.4.5- Summary 214
Contents XV
10. InGaN Single-Quantum-Well LEDs 215
10.1 High-Brightness InGaN Blue, Green, and Yellow LEDs
with Quantum-Well Structures 215
10.1.1 Introduction 215
10.1.2 Experimental Details 216
10.1.3 Results and Discussion 217
10.1.4 Summary 220
10.2 High-Power InGaN Single-Quantum-Well Blue
and Violet Light Emitting Diodes 220
10.3 Super-Bright Green InGaN Single-Quantum-Well Light
Emitting Diodes 223
10.3.1 Introduction 223
10.3.2 Experimental Details 224
10.3.3 Results and Discussion 225
10.3.4 Summary 229
10.4 White LEDs 230
11. Room-Temperature Pulsed Operation of Laser Diodes . . . . 237
11.1 InGaN-Based Multi-Quantum-Well Laser Diodes 237
11.1.1 Introduction 237
11.1.2 Experimental Deatils 237
11.1.3 Results and Discussion 239
11.1.4 Summary 242
11.2 InGaN Multi-Quantum-Well Laser Diodes
with Cleaved Mirror Cavity Facets 242
11.2.1 Introduction 242
11.2.2 Experimental Details 242
11.2.3 Results and Discussion 244
11.2.4 Summary 247
11.3 InGaN Multi-Quantum-Well Laser Diodes Grown on MgAl2O4
Substrates 247
11.3.1 Characteristics of InGaN Multi-Quantum-Well
Laser Diodes 252
11.4 The First III-V-Nitride-Based Violet Laser Diodes 256
11.4.1 Introduction 256
11.4.2 Experimental Details 256
11.4.3 Results and Discussion 258
11.4.4 Summary 262
11.5 Optical Gain and Carrier Lifetime
of InGaN Multi-Quantum-Well Laser Diodes 262
11.6 Ridge-Geometry InGaN Multi-Quantum-Well Laser Diodes . . 268
11.7 Longitudinal Mode Spectra and Ultrashort Pulse Generation
of InGaN Multi-Quantum-Well Laser Diodes 273
XVI Contents
12. Emission Mechanisms of LEDs and LDs 279
12.1 InGaN Single-Quantum-Well (SQW)-Structure LEDs 279
12.2 Emission Mechanism of SQW LEDs 281
12.3 InGaN Multi-Quantum-Well (MQW)-Structure LDs 284
12.4 Summary 289
13. Room Temperature CW Operation of InGaN MQW LDs . 291
13.1 First Continuous-Wave Operation of InGaN
Multi-Quantum-Well-Structure Laser Diodes at 233 K 291
13.2 First Room-Temperature Continuous-Wave Operation
of InGaN Multi-Quantum-Well-Structure Laser Diodes 296
13.5 RT CW Operation of InGaN MQW LDs
with a Long Lifetime 301
13.6 Blue/Green Semiconductor Laser 305
13.6.1 Blue/Green LEDs 305
13.6.2 Bluish-Purple LDs 307
13.6.3 Summary 313
13.7 RT CW InGaN MQW LDs with improved Lifetime 314
14. Latest Results: Lasers with Self-Organized InGaN Quantum
Dots 319
14.1 Introduction 319
14.2 Fabrication 319
14.3 Emission Spectra 320
14.4 Self-Organized InGaN Quantum Dots 325
14.5 Advances in LEDs 326
14.6 Advances in Laser Diodes 328
15. Conclusions 335
15.1 Summary 335
15.2 Outlook 336
Appendix 339
Biographies 343
Shuji Nakamura 343
Gerhard Fasol 344
Stephen Pearton 345
References 347
Index 361
