Semiconductor Nanophotonics: Materials, Models, and Devices

Preface
Contents
Contributors
1 A Short Introduction to Semiconductor Nanophotonics
	1.1 Nanophotonics and Internet Traffic
	1.2 Nanophotonics and Cyber Security
	1.3 Economic Impact of Nanophotonics
	1.4 Semiconductor Nanophotonics
	References
2 Submonolayer Quantum Dots
	2.1 Carrier Localization in Quantum Dots
		2.1.1 Stranski-Krastanow and Submonolayer Quantum Dots
		2.1.2 Electronic Structure of InAs Submonolayer Quantum Dots
	2.2 Epitaxy of Submonolayer Quantum Dots
		2.2.1 InAs/GaAs Submonolayers
		2.2.2 InAs/GaAs Submonolayers with Antimony
	2.3 Atomic Structure of Submonolayer Quantum Dots
		2.3.1 Methods for Structural Analysis
		2.3.2 Analysis of InAs Submonolayer Depositions
		2.3.3 Analysis of InAs Submonolayer Depositions with Antimony
	2.4 Optical and Excitonic Properties
		2.4.1 InAs Submonolayer Quantum-Dot Ensembles
		2.4.2 InAs:Sb Submonolayer Quantum-Dot Ensembles
	2.5 Devices Based on Submonolayer Quantum Dots
		2.5.1 Gain and Efficiency
		2.5.2 Amplitude-Phase Coupling
	2.6 Conclusion and Perspectives
	References
3 Stressor-Induced Site Control of  Quantum Dots for Single-Photon Sources
	3.1 Site-Controlled Nucleation of Quantum Dots
	3.2 Simulation of Strain
		3.2.1 Model for Strain Simulation
		3.2.2 Strain in a Mesa and in a Lamella Structure
	3.3 Nucleation Control by a Buried Aperture Stressor
		3.3.1 Development of a Buried-Stressor Design
		3.3.2 Proof-of-Principle for Stressor-Controlled Nucleation
		3.3.3 Site-Control of Single Quantum Dots
	3.4 Strain Measurement Applying Electron Holography
		3.4.1 Reconstruction of the Strain Tensor
		3.4.2 Phase Analysis of Dark-Field Electron Holography
		3.4.3 Strain Analysis in a Lamella of a GaAs Mesa
	3.5 Single-Photon Source Based on Stressor-Induced Site Control of Quantum Dots
		3.5.1 Development of an Electroluminescence Quantum-Dot Diode
		3.5.2 Operation Characteristics of a Single-Photon Source
		3.5.3 Development of a Resonant-Cavity Structure
	3.6 Realization of an Efficient Current Injection into a Single Quantum Dot
		3.6.1 Modeling of the Current Flow in the Device
		3.6.2 Current Confinement in pin and ppn Designs
		3.6.3 Demonstration of a ppn QD Diode with Efficient Current Confinement
	3.7 Conclusion and Perspectives
	References
4 Coherent and Incoherent Dynamics  in Quantum Dots and Nanophotonic Devices
	4.1 Introduction
	4.2 Ultrafast Carrier Dynamics in Semiconductors  with Reduced Dimensionality
		4.2.1 Ultrafast Gain and Phase Recovery Dynamics
		4.2.2 Ultrafast Coherent Optical Nonlinearities
		4.2.3 Crossed Excitons
		4.2.4 Quantum State Tomography
	4.3 Multisection Mode-Locked Semiconductor Lasers
		4.3.1 Delay Differential Equation Modeling
		4.3.2 Timing Jitter Calculation
		4.3.3 Reducing Timing Jitter by Optical Perturbations
		4.3.4 Tapered Multi-section Mode-Locked Laser
	4.4 Conclusion
	References
5 Optical and Structural Properties of Nitride Based Nanostructures
	5.1 Introduction
	5.2 Advanced Tools for Nanostructure Characterization
		5.2.1 TEM/STEM-CL
		5.2.2 Tip-Enhanced Raman Spectroscopy (TERS)
		5.2.3 UV Optical and Quantum-Optical Characterization
		5.2.4 XRD
		5.2.5 Scanning Tunneling Microscopy and Spectroscopy (STM/STS)
	5.3 Analysis of Nanostructure Growth in Nitrides
		5.3.1 Growth of Nitride Based Nano- and Micro-columns
	5.4 Optical Analysis of Low-Dimensional Nitrides
		5.4.1 Luminescence and Composition Inhomogeneities in InGaN/GaN Micro-columns
		5.4.2 InGaN/GaN Core-Shell Nanorods with Thick InGaN Shell
		5.4.3 Full InGaN/GaN LED Micro-column Structures
		5.4.4 Shielding Electric Fields in Nanowire Based Quantum-Heterostructures
		5.4.5 Optical Properties and Charge Carrier Dynamics in 1D Quantum Wires
	5.5 Conclusion and Perspectives
	References
6 Theory of Spectroscopy and Light Emission of Semiconductors Nanostructures
	6.1 Introduction
	6.2 State of the Art of Microscopic Description of Quantum Dots
		6.2.1 Quantum Dot Model
		6.2.2 Electron-Light Interaction
		6.2.3 Electron-Phonon Interaction
		6.2.4 Coulomb Interaction
	6.3 Coupled Quantum Dot-Cavity Structures
		6.3.1 Correlation Function and Master Equation
		6.3.2 Polarization-Entanglement
		6.3.3 Spatial Cross Correlation of Weakly and Strongly Coupled Modes: Single, Bunched and Heralded QD Photon Sources
		6.3.4 Effective Description of the Few and Many Emitter Limit and Application to Many Emitter Nanolasing
	6.4 Intraband Transitions Between Bound Quantum Dot States and States of the Host Medium
		6.4.1 Quantum Dot-Continuum Model System and Pump Probe Setup
		6.4.2 All-Optical Reconstruction of Quantum Dot Wave Functions
		6.4.3 Influence of Coulomb Coupling on Bound-Continuum Intraband Transitions
	6.5 Hybrid Density Matrix Approach as a Factorization Scheme for Many-Body Systems
	6.6 Two-Dimensional Spectroscopy in Semiconductor Nanostructures
		6.6.1 Theory of Four-Wave Mixing Spectroscopy
		6.6.2 Mechanisms of Coulomb Interaction in Quantum Dots
		6.6.3 Phase-Referenced 2D Spectroscopy of Coherently Coupled Individual QDs
		6.6.4 Förster and Dexter Transfer Processes in Coupled Nanostructures
		6.6.5 Localization Dynamics of Excitons in Disordered Semiconductor Quantum Wells
	6.7 Conclusion
	References
7 Multi-dimensional Modeling and Simulation of Semiconductor Nanophotonic Devices
	7.1 Introduction
	7.2 Basic Concepts
		7.2.1 Electronic Transport
		7.2.2 Optical Fields
		7.2.3 Thermodynamics
	7.3 Quantum Dot Based Light-Emitting Devices
		7.3.1 Quantum Dot Lasers
		7.3.2 Single-Photon Sources
	7.4 Numerical Methods
		7.4.1 Numerical Methods for the Drift-Diffusion Equations
		7.4.2 Finite-Element Approach to Maxwell\'s Equations
	7.5 Applications
		7.5.1 Quantum Dot Single-Photon Sources
		7.5.2 Vertical-Cavity Surface-Emitting Lasers
		7.5.3 Grating Couplers
		7.5.4 Efficient Current Injection into Oxide-Confined Pn-Diodes
	7.6 Conclusion and Outlook
	References
8 Deterministic Quantum Devices  for Optical Quantum Communication
	8.1 Introduction
	8.2 Numerical Modeling and Optimization of Quantum Devices for the Generation and Distribution of Single Photons
		8.2.1 A Setup for a QD-Based Fiber-Coupled Single-Photon Source
		8.2.2 Numerical Method for the Efficient Simulation  of Optical Devices with Embedded QDs
		8.2.3 Numerical Optimization of the Light Extraction  from a Single-Photon Source
		8.2.4 Numerical Simulation of a QD-Based Single-Photon Emitting Diode—The Role of Electrical Carrier Injection
	8.3 Deterministic Fabrication Technologies
		8.3.1 Ex-situ Schemes
		8.3.2 In-situ Schemes
	8.4 Quantum Light Sources Based on Deterministic Quantum Dot Microlenses
		8.4.1 Microlenses for Enhanced Photon Extraction
		8.4.2 Description of Sample Templates and Spectroscopic Techniques
		8.4.3 Device Yield and Photon-Extraction Efficiency
		8.4.4 Verification of Single-Photon Emission
		8.4.5 Generation of Indistinguishable Photons
		8.4.6 Demonstration of a Twin-Photon Source
		8.4.7 Generation of Polarization-Entangled Photon Pairs
		8.4.8 Strain Tuning of the Emission Energy
		8.4.9 Quantum Dot Single-Photon Sources Emitting at Telecom Wavelength
	8.5 On-Chip Quantum Circuits with Deterministically-Integrated Quantum Dots
		8.5.1 Fabrication of Monolithic Waveguide Structures and an On-Chip HBT Circuit
	8.6 Conclusion and Outlook
	References
9 Quantum Networks Based on Single Photons
	9.1 Introduction
	9.2 Single-Photon Generation and Manipulation
		9.2.1 Properties of Single Photons in Quantum Networks
		9.2.2 Semiconductor Single-Photon Sources
	9.3 Frequency Conversion of Quantum Light
		9.3.1 Nonlinear Quantum-Optics
		9.3.2 Conversion of Photons in the Telecom Band
		9.3.3 Conversion of Photons from a Single Quantum Dot
	9.4 Single-Photon Storage
		9.4.1 Concepts of Photon Storage
		9.4.2 Atomic Gas Cells
		9.4.3 Interfacing Quantum Dots and Atomic Vapors
		9.4.4 Single-Photon Storage
	9.5 Quantum Communication
		9.5.1 Quantum Key Distribution (QKD) Protocols
		9.5.2 The Time-Frequency (TF-) Protocol
		9.5.3 Numerical Studies, Higher Alphabets and Security Issues
	9.6 Free-Space Quantum Link
		9.6.1 Free Space QKD Transmission
		9.6.2 Experimental Implementation of a Quantum Testbed
		9.6.3 Evaluation and Improvements
	9.7 Conclusion and Outlook
	References
10 Vertical Cavity Surface Emitting Laser Diodes for Communication, Sensing, and Integration
	10.1 Introduction
	10.2 VCSEL Experimental Structures
	10.3 VCSEL Processing, Geometric Variations, and Characterization
	10.4 Reduced Vertical Dimension VCSELs
	10.5 High Modulation Bandwidth VCSELs
	10.6 VCSELs for Higher Power
	10.7 VCSEL Arrays
	10.8 Conclusion and Outlook
	References
11 VCSEL-Based Silicon Photonic Interconnect Technologies
	11.1 Modern Interconnect Technologies and Requirements
		11.1.1 Classification of Interconnects
		11.1.2 Road to Coherent Data Center Interconnects
		11.1.3 On the Importance of Quantum Dot Lasers for Silicon Photonics
	11.2 Long-Wavelength VCSELs
		11.2.1 Device Structure
		11.2.2 Operation Characteristics
	11.3 Characterization of 1.33 µm and 1.55 µm InP VCSELs for Coherent Interconnects
		11.3.1 Intrinsic Linewidth
	11.4 Modeling of VCSEL-Based Coherent Interconnects
		11.4.1 Coherent Transmission Techniques
		11.4.2 Digital Signal Processing
		11.4.3 Performance of VCSEL-Based Transmission Links for QPSK
	11.5 VCSEL-Based PAM-4 Transmission Link
		11.5.1 Setup
		11.5.2 System Performance
	11.6 VCSEL-Based QPSK Transmission Link
		11.6.1 Setup
		11.6.2 System Performance
	11.7 Conclusion
	References
12 Nitride Microcavities and Single Quantum Dots for Classical and Non-classical Light Emitters
	12.1 Introduction
	12.2 Bragg Mirrors in the Visible to Deep UV Spectral Region
	12.3 Microstructure and Emission Properties of Blue/Violet Emitting III-Nitride Microcavities
		12.3.1 Electric Fields Within AlGaN/AlInN DBRs
		12.3.2 Plastic Relaxation of 62-Fold InGaN Multiple Quantum Wells in a GaN Cavity
		12.3.3 Carrier Localization in a Pseudomorphically Grown InGaN MQW/DBR Structure
		12.3.4 Local Properties of Excitonic and Photonic Modes in Violet Emitting Microcavities
	12.4 GaN Quantum Dots: Formation, Optical and Electronic Properties
		12.4.1 GaN Quantum Dot Formation Mechanism
		12.4.2 Quantum Dot Emission from GaN Islands Formed at Threading Dislocations
		12.4.3 Exciton-Phonon Coupling
		12.4.4 Spectral Diffusion of Excitonic Complexes
		12.4.5 Photon Statistics of the Biexciton Cascade
		12.4.6 Unconventional Biexciton States
		12.4.7 Monolithic Deep UV Bragg Mirrors for GaN QD Microcavities
	12.5 Towards Electrically Driven Microcavity Devices
	12.6 Conclusion and Perspectives
	References
13 Group III-Nitride-Based UV Laser Diodes
	13.1 Introduction
	13.2 State-of-the-Art in Group III-Nitride Laser Diode Technologies
		13.2.1 Near UV and Blue Laser Diodes
		13.2.2 Optically Pumped Deep UV Lasers
		13.2.3 Electron Beam Pumping of UV Emitters
		13.2.4 AlGaN-Based Deep UV Laser Diodes
	13.3 Design of AlGaN-Based Deep UV Laser Diodes
		13.3.1 Separate Confinement Heterostructure
		13.3.2 Design Rules for Deep UV Laser Heterostructures
		13.3.3 Investigated Deep UV Laser Structures
	13.4 Fabrication of AlGaN-Based UV Laser Diodes
		13.4.1 Low Resistance Ohmic Contacts to n-AlGaN Layer
	13.5 Low Defect Density AlN Templates
		13.5.1 Substrates and Templates for AlGaN UV Lasers
		13.5.2 Bulk AlN Substrates
		13.5.3 SiC Substrates
		13.5.4 Sapphire Substrates
	13.6 Growth of AlGaN Laser Heterostructures
		13.6.1 Pseudomorphic Growth of AlGaN and Critical Layer Thickness
		13.6.2 Si- and Mg-Doping of AlGaN Materials and Superlattices
		13.6.3 Growth and Optical Properties of AlGaN Quantum Wells
	13.7 Gain and Losses in Deep UV AlGaN Lasers by Optical Pumping
		13.7.1 Optical Pumping for Lasing Threshold and Gain Measurements
		13.7.2 Optical Gain in Dependence of the Emission Wavelength
		13.7.3 Optical Polarization and Valence Band Ordering
		13.7.4 Loss Mechanisms in Deep UV Lasers
	13.8 Development of Current Injection Deep UV Laser Diodes
		13.8.1 Low Resistance n-AlGaN Current Spreading Layers
		13.8.2 Mg-Doped AlGaN Short Period Superlattices
		13.8.3 Efficient Carrier Injection and Carrier Confinement in Deep UV AlGaN LDs by Electron Blocking Heterostructures
		13.8.4 Efficient Carrier Injection in Deep UV AlGaN LD by Tunnel Heterojunctions
		13.8.5 High Density Pulsed Current Injection in UV Laser Diodes
	13.9 Conclusion and Outlook
	References
Index