Introduction to Nitride Semiconductor Blue Lasers and Light Emitting Diodes

Transcription

1 Introduction to Nitride Semiconductor Blue Lasers and Light Emitting Diodes Edited by Shuji Nakamura and Shigefusa F. Chichibu London and New York

2 Contents 1. Basics Physics and Materials Technology of GaN LEDs and LDs... 1 Steven P. DenBaars 1.1 Introduction Historical Evolution of LED Technology Basic Physics of LEDs: Injection Luminescence Direct and Indirect Band-Gap Material Radiative Recombination External Quantum Efficiency Luminous Efficiency Injection Efficiency Heterojunction vs. Homojunction LED Materials Quantum Well LEDs LED Materials Selection Energy Band Structure/Lattice Constants GaN Physical Properties GaN Based LED Structures Crystal Growth MOCVD Growth MOCVD Systems for Production Molecular Beam Epitaxy (MBE) Chloride Vapor Phase Epitaxy Group-Ill Nitride Materials Growth Issues Substrates Nucleation Layer Technology Growth and Doping of GaN Growth of AlGaN and AlGaN/GaN Heterostructures Growth of InGaN and InGaN/GaN Heterostmctures Conclusions References Theoretical Analysis of Optical Gain Spectra 29 Takeshi Uenoyama and Masakatsu Suzuki 2.1 Introduction Optical Gains Spectra by Many-Body Approach Linear Response Theory 30

3 2.2.2 Screening Effects Self-Energies of Electron Gas Coulomb Enhancement Electronic Band Structures Electronic Band Structures of Bulk GaN and A1N Strain Effect on Electronic Band Structures kp Theory for Wurtzite Physical Parameters Subband Structures of GaN/AlGaN Quantum Wells Subband in Wurtzite Quantum Wells Optical Gain Spectra oflll-v Nitrides LD Structures Free Carrier Model Coulomb Enhancement (Excitonic Effects) in the Optical Gain Optical Gain with Localized States Conclusions References Electrical Conductivity Control 67 Chris G. Van de Walle 3.1 Doping Theory of Native Defects and Impurities n-type Doping p-type Doping Band Offsets Theory of Band Offsets at Nitride Interfaces Experimental Results for Band Offsets Discussion Acknowledgments References Crystal Defects and Device Performance in LEDs and LDs Fernando A. Ponce 4.1 CrystalGrowth and Microstructure Lattice Structure of the Nitride Semiconductors Thin Film Epitaxy and Substrates Epitaxy on SiC Substrates Epitaxy on Sapphire Substrates Ill A1N as a Buffer Layer GaN as a Buffer Layer Homoepitaxial Growth of GaN Defect Microstructurein LEDs and LDs Large Defect Densities in High Performance Materials Columnar Structure of GaN on Sapphire Tilt Boundaries 121

4 4.5.4 Twist Boundaries Polarity and Electronic Properties The Nature of the Dislocation Determination of the Burgers Vector Nanopipes and Inversion Domains Spatial Variation of Luminescence Undoped Material Doped Materials Microscopic Properties of In x Gai_ x N Quantum Wells The Nature of the InGaN/GaN Interface Microstructure of Quantum Wells Spatial Variation of the luminescence of In x Gai_ x N Quantum Wells Microstructure and Device Performance Stress and Point Defect Structure Minimization of Strain by Maximizing Film Smoothness The Role of Dislocations in Strain Relaxation The Role of Nanopipes and Extension to ELOG Structures References Emission Mechanisms and Excitons in GaN and InGaN Bulk and QWsl53 Shigefusa F. Chichibu, Yoichi Kawakami, and Takayuki Sota 5.1 Introduction GaN Bulk Crystals Free and Bound Excitons Biexcitons in GaN Strain Effects Phonons in Nitrides InGaN Bulk and QWs for Practical Devices Quantized Energy Levels Piezoelectric Field Spontaneous Emission of Localized Excitons Localized Exciton Dynamics Optical Gain in Nitrides References Life Testing and Degradation Mechanisms in InGaN LEDs 271 Marek Osinski and Daniel L. Barton 6.1 Introduction Life Testing of InGaN/AlGaN/GaN LEDs Life Testing Primer Potential Degradation Regions in LEDs Life Test System Considerations Results of Life Tests on Nichia Blue InGaN/AlGaN/GaN

5 Double Heterostracture LEDs Analysis of Early Test Failures Analysis of LED # Analysis of LEDs #16 and Effects ofuv Emission on Plastic Transparency Thermal Degradation of Plastic Package Transparency Degradation of GaN-Based LEDs Under ffigh Current Stress Double Heterostracture Device Testing EBIC Analysis Pulsed Current Stress Experiments and Results on Quantum Well LEDs Failure Analysis of Degraded Quantum Well LEDs Discussion Summary References Development and Future Prospects of GaN-based LEDs and LD Shuji Nakamura 7.1 Properties of InGaN-based LEDs Introduction Amber LEDs UV/Blue/Green LEDs Roles of Dislocations in InGaN-Based LEDs LDs Grown on Sapphire Substrate Introduction LDs Grown on Sapphire Substrates ELOG Substrate InGaN-Based LDs Grown on ELOG Substrates LDs Grown on GaN Substrate Free-Standing GaN Substrates Characteristics of LDs Future Prospects of InGaN-based Emitting Devices References 348 Appendix Parameters Table 351 Subject Index 369