1 Thermodynamics and Kinetics of Quantum Dot Growth&Vitaly Shchukin,Eckehard Sch？ll and Peter Kratzer 1
1.1 Introduction 2
1.1.1 Length and Time Scales 3
1.1.2 Multiscale Approach to the Modeling of Nanostructures 4
1.2 Atomistic Aspects of Growth 5
1.2.1 Diffusion of Ga Atoms on GaAs(001) 5
1.2.2 Energetics of As2 Incorporation During Growth 5
1.2.3 Kinetic Monte Carlo Simulation of GaAs Homoepitaxy 6
1.2.4 Wetting Layer Evolution 9
1.3 Size and Shapes ofIndividual Quantum Dots 11
1.3.1 Hybrid Approach to Calculation of the Equilibrium Shape of Individual Quantum Dots 11
1.3.2 Role of High-Index Facets in the Shape of Quantum Dots 13
1.3.3 Shape Transition During Quantum Dot Growth 14
1.3.4 Constraint Equilibrium of Quantum Dots with a Wetting Layer 15
1.4 Thermodynamics and Kinetics of Quantum Dot Ensembles 19
1.4.1 Equilibrium Volume of Strained Islands versus Ostwald Ripening 19
1.4.2 Crossover from Kinetically Controlled to Thermodynamically Controlled Growth ofQuantum Dots 22
1.4.3 Tunable Metastability of Quantum Dot Arrays 25
1.4.4 Evolution Mechanisms in Dense Arrays of Elastically Interacting Quantum Dots 27
1.5 Quantum Dot Stacks 29
1.5.1 Transition between Vertically Correlated and Vertically Anticorrelated Quantum Dot Growth 29
1.5.2 Finite Size Effect:Abrupt Transitions between Correlated and Anticorrelated Growth 31
1.5.3 Reduction of a Size of a Critical Nucleus in the Second Quantum Dot Layer 32
1.6 Summary and Outlook 34
References 35
2 Control of Self-Organized In(Ga)As/GaAs Quantum Dot Growth&Udo W.Pohl and André Strittmatter 41
2.1 Introduction 41
2.2 Evolution and Strain Engineering of InGaAs/GaAs Quantum Dots 42
2.2.1 Evolution of InGaAs Dots 42
2.2.2 Engineering of Single and Stacked InGaAs QD Layers 46
2.3 Growth Control of Equally Shaped InAs/GaAs Quantum Dots 50
2.3.1 Formation of Self-Similar Dots with a Multimodal Size Distribution 51
2.3.2 Kinetic Description of Multimodal Dot-Ensemble Formation 54
2.4 Epitaxy of GaSb/GaAs Quantum Dots 56
2.4.1 Onset and Dynamics of GaSb/GaAs Quantum-Dot Formation 56
2.4.2 Structure ofGaSb/GaAs Quantum Dots 58
2.5 Device Applications of InGaAs Quantum Dots 60
2.5.1 Edge-Emitting Lasers 60
2.5.2 Surface-Emitting Lasers 61
2.6 Conclusion 62
References 63
3 In-Situ Monitoring for Nano-Structure Growth in MOVPE&Markus Pristovsek and Wolfgang Richter 67
3.1 Introduction 67
3.2 Reflectance 69
3.3 Reflectance Anisotropy Spectroscopy(RAS) 71
3.3.1 RAS Spectra and Surface Reconstruction 72
3.3.2 Monolayer Oscillations 74
3.3.3 Monitoring of Carrier Concentration 79
3.4 Scanning Tunneling Microscopy(STM) 82
3.5 Conclusion 84
References 85
4 Bottom-up Approach to the Nanopatterning of Si(001)&R.Koch 87
4.1 Quantum Dot Growth on Semiconductor Templates 87
4.2 (2×n)Reconstruction of Si(001) 88
4.3 Monte Carlo Simulations on the (2×n)Formation 90
4.4 Scanning Tunneling Microscopy Results 92
4.5 Summary and Outlook 94
References 95
5 Structural Characterisation of Quantum Dots by X-Ray Diffraction and TEM&R.K？hler,W.Neumann,M.Schmidbauer,M.Hanke,D.Grigoriev,P.Sch？fer,H.Kirmse,I.H？usler and R.Schneider 97
5.1 Introduction 97
5.2 Liquid Phase Epitaxy of SiGe/Si:A Model System for the Stranski-Krastanow Process 99
5.2.1 Dot Evolution in a Close-to-Equilibrium Regime 99
5.3 (In,Ga)As Quantum Dots on GaAs 103
5.3.1 Shape,Size,Strain and Composition Gradient in InGaAs QD Arrays 103
5.3.2 Chemical Composition of(In,Ga)As QDs Determined by TEM 107
5.3.3 Controlling 3D Ordering in(In,Ga)As QD Arrays through GaAs Surface Orientation 109
5.4 Ga(Sb,As)Quantum Dots on GaAs 113
5.4.1 Structural Characterisation of Ga(Sb,As)QDs by High-Resolution TEM Imaging 117
5.4.2 Chemical Characterisation of Ga(Sb,As)QDs by HAADF STEM Imaging 118
References 119
6 The Atomic Structure of Quantum Dots&Mario D？hne,Holger Eisele and Karl Jacobi 123
6.1 Introduction 123
6.2 Experimental Details 124
6.3 STM Studies of InAs Quantum Dots on the Growth Surface 124
6.4 XSTM Studies of Buried Nanostructures 127
6.4.1 InAs Quantum Dots 127
6.4.2 InGaAs Quantum Dots 131
6.4.3 GaSb Quantum Dots 134
6.5 Conclusion 135
References 136
7 Theory of Excitons in InGaAs/GaAs Quantum Dots&Andrei Schliwa and Momme Winkelnkemper 139
7.1 Introduction 139
7.2 Interrelation of QD-Structure,Strain and Piezoelectricity,and Coulomb Interaction 140
7.2.1 The Binding Energies of the Few Particle Complexes 140
7.3 Method of Calculation 143
7.3.1 Calculation of Strain 144
7.3.2 Piezoelectricity and the Reduction of Lateral Symmetry 145
7.3.3 Single Particle States 147
7.3.4 Many-Particle States 148
7.3.5 The Configuration Interaction Model 148
7.3.6 Interband Spectra 150
7.4 The Investigated Structures:Variation of Size,Shape and Composition 150
7.5 The Impact of QD Size 151
7.5.1 The Role of the Piezoelectric Field 153
7.6 The Aspect Ratio 155
7.6.1 Vertical Aspect Ratio 155
7.6.2 Lateral Aspect Ratio 157
7.7 Different Composition Profiles 157
7.7.1 Inverted Cone-Like Composition Profile 157
7.7.2 Annealed QDs 159
7.7.3 InGaAs QDs with Uniforrn Composition 159
7.8 Correlation vs.QD Size,Shape and Particle Type 159
7.9 Conclusions 162
References 163
8 Phonons in Quantum Dots and Their Role in Exciton Dephasing&F.Grosse,E.A.Muljarov and R.Zimmermann 165
8.1 Introduction 165
8.2 Structural Properties of Semiconductor Nanostructures 166
8.3 Theory of Acoustic Phonons in Quantum Dots 166
8.3.1 Continuum Elasticity Model of Phonons 167
8.3.2 Phonons in Quantum Dots 170
8.4 Exciton-Acoustic Phonon Coupling in Quantum Dots 171
8.5 Dephasing of the Exciton Polarization in Quantum Dots 173
8.5.1 Single Exciton Level:Independent Boson Model 174
8.5.2 Multilevel System:Real and Virtual Phonon-Assisted Transitions 176
8.5.3 Application to Coupled Quantum Dots 182
8.6 Summary 184
References 185
9 Theory of the Optical Response of Single and Coupled Semiconductor Quantum Dots&C.Weber,M.Richter,S.Ritter and A.Knorr 189
9.1 Introduction 189
9.2 Theory 190
9.2.1 Quantum Dot Model 190
9.2.2 Hamiltonian 191
9.2.3 Mathematical Formalisms 193
9.3 Single Quantum Dot Response 196
9.3.1 Linear Absorption Spectra and Quantum Optics 196
9.3.2 Semiclassical Nonlinear Dynamics 199
9.4 Two Coupled Quantum Dots 201
9.4.1 Absorption Spectra 202
9.4.2 Excitation Transfer 202
9.4.3 Rabi Oscillations 203
9.4.4 Pump-Probe/Differential Transmission Spectra 204
9.5 Multiple Quantum Dots 205
9.5.1 Four-Wave-Mixing:Photon Echo in Quantum Dot Ensembles 205
9.5.2 Absorption of Multiple Coupled Quantum Dots 205
9.5.3 Energy Transfer of Multiple Coupled Quantum Dots 206
9.6 Conclusion 206
References 207
10 Theory of Nonlinear Transport for Ensembles of Quantum Dots&G.Kieβlich,A.Wacker and E.Sch？ll 211
10.1 Introduction 211
10.2 Coulomb Interaction within a Quantum Dot Layer 211
10.3 Transport in Quantum Dot Stacks 213
10.4 Current Fluctuations and Shot Noise 214
10.5 Full Counting Statistics and Decoherence in Coupled Quantum Dots 216
10.6 Conclusion 218
References 219
11 Quantum Dots for Memories&M.Geller and A.Marent 221
11.1 Introduction 221
11.2 Semiconductor Memories 222
11.2.1 Dynamic Random Access Memory(DRAM) 222
11.2.2 Nonvolatile Semiconductor Memories(Flash) 223
11.2.3 A QD-based Memory Cell 224
11.3 Charge Carrier Storage in Quantum Dots 226
11.3.1 Experimental Technique 226
11.3.2 Carrier Storage in InGaAs/GaAs Quantum Dots 228
11.3.3 Hole Storage in GaSb/GaAs Quantum Dots 229
11.3.4 InGaAs/GaAs Quantum Dots with Additional AlGaAs Barrier 230
11.4 Conclusion and Outlook 233
References 235
12 Visible-Bandgap Ⅱ-Ⅵ Quantum Dot Heterostructures&Ilya Akimov,Joachim Puls,Michael Rabe and Fritz Henneberger 237
12.1 Introduction 237
12.2 Epitaxial Growth 238
12.3 Few-Particles States and Their Fine Structure 241
12.3.1 Excitons and Biexcitons 241
12.3.2 Trions in Charged Quantum Dots 243
12.4 Coherent Control of the Exciton-Biexciton System 245
12.5 Spin Relaxation of Excitons,Holes,and Electrons 247
12.5.1 Exciton Quantum Coherence 247
12.5.2 Hole Spin Lifetime 248
12.5.3 Spin Dynamics of the Resident Electron 249
12.6 Diluted Magnetic Quantum Dots 251
References 253
13 Narrow-Gap Nanostructures in Strong Magnetic Fields&T.Tran-Anh and M.Ortenberg 255
13.1 Introduction 255
13.2 Materials:HgSe/HgSe:Fe 256
13.3 Fabrication ofHgSe/HgSe:Fe Nanostructures 256
13.3.1 Quantum Wells 257
13.3.2 Roof-Ridge Quantum Wires 258
13.3.3 Quantum Dots 259
13.4 Electronic Characterization of the HgSe/HgSe:Fe Nano-Structures in Strong Magnetic Fields 262
13.4.1 High-Field Magneto Transport 262
13.4.2 Infrared Magneto-Resonance Spectroscopy 263
13.5 Summary 267
References 267
14 Optical Properties of Ⅲ-Ⅴ Quantum Dots&Udo W.Pohl,Sven Rodt and Axel Hoffmann 269
14.1 Introduction 269
14.2 Confined States and Many-Particle Effects 270
14.2.1 Renormalization 270
14.2.2 Phonon Interaction 274
14.2.3 Electronic Tuning by Strain Engineering 276
14.2.4 Multimodal InAs/GaAs Quantum Dots 278
14.3 Single InAs/GaAs Quantum Dots 281
14.3.1 Spectral Diffusion 281
14.3.2 Size-Dependent Anisotropic Exchange Interaction 282
14.3.3 Binding Energies of Excitonic Complexes 285
14.3.4 Data Storage Using Confined Trions 286
14.3.5 Electronic Tuning by Annealing 287
14.4 Optical Properties ofInGaN/GaN Quantum Dots 288
14.4.1 Time-Resolved Studies on Quantum Dot Ensembles 289
14.4.2 Single-Dot Spectroscopy 292
14.5 Summary 296
References 298
15 Ultrafast Coherent Spectroscopy of Single Semiconductor Quantum Dots&Christoph Lienau and Thomas Elsaesser 301
15.1 Introduction 301
15.2 Interface Quantum Dots 303
15.3 Coherent Spectroscopy of Interface Quantum Dots:Experimental Technique 305
15.4 Coherent Controlin Single Interface Quantum Dots 308
15.4.1 Ultrafast Optical Nonlinearities of Single Interface Quantum Dots 308
15.4.2 Rabi Oscillations in a Quantum Dot 312
15.4.3 Optical Stark Effect:Ultrafast Control of Single Exciton Polarizations 315
15.5 Coupling Two Quantum Dots via the Dipole-Dipole Interaction 319
15.6 Summary and Conclusions 323
References 325
16 Single-Photon Generation from Single Quantum Dots&Matthias Scholz,Thomas Aichele and Oliver Benson 329
16.1 Introduction 329
16.2 Single Quantum Dots as Single-Photon Emitters 331
16.2.1 Photon Statistics of Single-Photon Emitters 331
16.2.2 Micro-Photoluminescence 332
16.2.3 Single Photons from InP Quantum Dots 333
16.3 Multiphoton Emission from Single Quantum Dots 334
16.4 Realization of the Ultimate Limit of a Light Emitting Diode 339
16.5 Applications in Quantum Information Processing 343
16.5.1 Quantum Key Distribution 343
16.5.2 Quantum Computing 344
16.6 Outlook 346
References 347
Index 351