Description
Book SynopsisThis book, the second of two volumes, describes heterostructures and optoelectronic devices made from GaN and ZnO nanowires.
Over the last decade, the number of publications on GaN and ZnO nanowires has grown exponentially, in particular for their potential optical applications in LEDs, lasers, UV detectors or solar cells. So far, such applications are still in their infancy, which we analyze as being mostly due to a lack of understanding and control of the growth of nanowires and related heterostructures. Furthermore, dealing with two different but related semiconductors such as ZnO and GaN, but also with different chemical and physical synthesis methods, will bring valuable comparisons in order to gain a general approach for the growth of wide band gap nanowires applied to optical devices.
Table of ContentsPREFACE xi
PART 1. GaN AND ZnO NANOWIRE HETEROSTRUCTURES 1
CHAPTER 1. AlGaN/GaN NANOWIRE HETEROSTRUCTURES 3
Jörg TEUBERT, Jordi ARBIOL and Martin EICKHOFF
1.1. A model system for AlGaN/GaN heterostructures 3
1.2. Axial AlGaN/GaN nanowire heterostructures 4
1.2.1. Structural properties of axial AlGaN/GaN nanowire heterostructures 5
1.2.2. Optical properties of axial AlGaN/GaN nanowire heterostructures 8
1.2.3. Lateral internal electric fields 12
1.2.4. Axial internal electric fields 14
1.2.5. Optical characterization of single-AlGaN/GaN nanowires containing GaN nanodisks 15
1.2.6. Electrical transport properties 18
1.3. AlGaN/GaN core–shell nanowire heterostructures 19
1.3.1. Structural properties 20
1.3.2. Optical characteristics 23
1.3.3. Electronic properties 24
1.3.4. True one-dimensional GaN quantum wire second-order self-assembly 28
1.4. Application examples 29
1.4.1. AlGaN/GaN nanowire heterostructure optochemical gas sensors 30
1.4.2. AlGaN/GaN nanowire heterostructure resonant tunneling diodes 33
1.5. Conclusions 34
1.6. Bibliography 35
CHAPTER 2. InGaN NANOWIRE HETEROSTRUCTURES 41
Bruno DAUDIN
2.1. Introduction 41
2.2. Self-assembled InGaN nanowires 43
2.3. X-ray characterization of InGaN nanowires 46
2.4. InGaN nanodisks and nanoislands in GaN nanowires 49
2.5. Selective area growth (SAG) of InGaN nanowires 52
2.6. Conclusion 55
2.7. Bibliography 56
CHAPTER 3. ZnO-BASED NANOWIRE HETEROSTRUCTURES 61
Guy FEUILLET and Pierre FERRET
3.1. Introduction 61
3.2. Designing ZnO-based nanowire heterostructures 63
3.3. Growth of ZnxMg1-xO/ZnO core–shell heterostructures by metal-organic vapor phase epitaxy 66
3.4. Misfit relaxation processes in Znx Mg1-xO/ZnO core–shell structures 70
3.5. Optical efficiency of core–shell oxidebased nanowire heterostructures 73
3.6. Axial nanowire heterostructures 76
3.7. Conclusions and perspectives 80
3.8. Bibliography 81
CHAPTER 4. ZnO AND Ga NANOWIRE-BASED TYPE II HETEROSTRUCTURES 85
Yong ZHANG
4.1. Semiconductor heterostructures 85
4.2. Type II heterostructures 87
4.3. Optimal device architecture 88
4.4. Electronic structure of type II core–shell nanowires 91
4.5. Synthesis of the type II core–shell nanowires and their signatures 94
4.6. Demonstration of type II effects in ZnO–ZnSe core–shell nanowires and photovoltaic devices 96
4.7. Summary 101
4.8. Acknowledgments 102
4.9. Bibliography 102
PART 2. INTEGRATION OF GaN AND ZnO NANOWIRES IN OPTOELECTRONIC DEVICES 105
CHAPTER 5. AXIAL GaN NANOWIRE-BASED LEDS 107
Qi WANG, Hieu N’GUYEN, Songrui ZHAO and Zetian MI
5.1. Introduction 107
5.2. Top-down GaN-based axial nanowire LEDs 108
5.2.1. Fabrication of top-down GaN-based axial nanowires 108
5.2.2. Device fabrication of axial nanowire LEDs 110
5.2.3. Performance characteristics of top-down axial nanowire LEDs 111
5.3. Bottom-up GaN-based axial nanowire LEDs 112
5.3.1. Growth techniques 112
5.3.2. Doping, polarity and surface charge properties 113
5.3.3. Design and typical performance of bottom-upaxial nanowire LEDs 114
5.4. Carrier loss processes of axial nanowire LEDs 121
5.4.1. Auger recombination 121
5.4.2. Electron overflow 122
5.4.3. Surface recombination 123
5.5. Controlling carrier loss of GaN-based nanowire LEDs 124
5.5.1. p-type modulation doping and AlGaN electron blocking layer 124
5.5.2. InGaN/GaN/AlGaN core–shell dot-in-a-wire phosphor-free white LEDs 126
5.6. Conclusions 127
5.7. Bibliography 127
CHAPTER 6. RADIAL GaN NANOWIRE-BASED LEDS 135
Shunfeng LI
6.1. Radial GaN nanowire-based LED: an emerging device 135
6.2. Growth of GaN nanowires and radial nanowire-based devices 138
6.3. Radial GaN nanowire-based LED structure 145
6.4. Characteristics of radial NW devices 150
6.5. Further work and perspectives 152
6.6. Bibliography 154
CHAPTER 7. GaN NANOWIRE-BASED LASERS 161
Xiang ZHOU, Jordan Paul CHESIN and Silvija GRADEÈAK
7.1. Introduction to nanowire lasers 161
7.2. Theoretical considerations and simulations 163
7.3. The first experimental observations of lasing in nanowires 165
7.4. GaN nanowire-based lasers 166
7.5. Toward wavelength tunability: nanowire lasers based on GaN/InxGa1-xN heterostructures 169
7.6. GaN nanowire lasers coupled with hybrid structures 171
7.7. Challenges and opportunities 173
7.8. Bibliography 175
CHAPTER 8. GaN NANOWIRE-BASED ULTRAVIOLET PHOTODETECTORS 179
Lorenzo RIGUTTI and Maria TCHERNYCHEVA
8.1. Introduction 179
8.2. Growth and fabrication techniques 180
8.3. GaN nanowire photoconductive detectors 183
8.4. p–i–n junction-based GaN nanowire detectors 187
8.5. Single-wire GaN/AlN multiple quantum disk photodetectors 190
8.6. Single-wire InGaN/GaN core–shell photodetectors 193
8.7. Conclusions 197
8.8. Acknowledgments 197
8.9. Bibliography 198
CHAPTER 9. ZnO NANOWIRE-BASED LEDS 203
Magnus WILLANDER and Omer NOUR
9.1. Outline 203
9.2. Introduction 203
9.3. Growth of ZnO nanowires 205
9.4. White light emission from ZnO nanowires 209
9.5. ZnO NW white LEDs on solid crystalline substrates 212
9.6. ZnO NWs white LEDs on flexible substrates 214
9.7. Enhancing the emission of ZnO nanowire-based LEDs 220
9.8. Conclusion and future prospective 222
9.9. Bibliography 222
CHAPTER 10. ZnO NANOWIRE-BASED SOLAR CELLS 227
Jason B. BAXTER
10.1. Introduction 227
10.1.1. Solar energy conversion and nanostructured solar cells 227
10.1.2. Use of ZnO in solar cells 228
10.2. ZnO nanowire dye-sensitized solar cells 229
10.3. Quantum dot-sensitized nanowire solar cells 235
10.4. Extremely thin absorber solar cells 237
10.5. Nanowire arrays completely filled with inorganic absorbers 239
10.6. ZnO nanorod – organic hybrid solar cells 241
10.7. ZnO nanowire arrays for photoelectrochemical water splitting 244
10.8. Conclusions 245
10.9. Acknowledgments 247
10.10. Bibliography 247
LIST OF AUTHORS 253
