Ill-Nitride Ultraviolet

Transcription

1 Michael Kneissl Jens Rass Editors Ill-Nitride Ultraviolet Emitters Technology and Applications & Springer

2 Contents 1 A Brief Review of Ill-Nitride UV Emitter Technologies and Their Applications 1 Michael Kneissl 1.1 Background UV Light Emitters and Their Applications UV-LEDs State of the Art and the Challenges Ahead UV-LEDs Key Parameters and Device Performance The Role of Defects on the IQE of UV-LEDs Current-Injection Efficiency and Operating Voltages of UV-LEDs Light Extraction from UV-LEDs Thermal Management and Degradation of UV-LED Outlook Summary 17 References 18 2 Growth and Properties of Bulk A1N Substrates 27 Matthias Bickermann 2.1 Properties and History of A1N Crystals A1N Bulk Growth by the PVT Method: Theory A1N Bulk Growth by the PVT Method: Technology Seeded Growth and Crystal Enlargement Structural Defects in PVT-Grown A1N Bulk Crystals Impurities and Resulting Properties of A1N Substrates Conclusions and Outlook 41 References 42 ix

3 x Contents 3 Vapor Phase Epitaxy of AlGaN Base Layers on Sapphire Substrates for Nitride-Based UV-Light Emitters 47 Eberhard Richter, Sylvia Hagedorn, Arne Knauer and Markus Weyers 3.1 Introduction Growth of Al(Ga)N Buffer Layers by MOVPE Techniques for MOVPE of Al(Ga)N Base Layers with Reduced TDD Growth of AlGaN Layers by HVPE Fundamentals of the HVPE Technique The Choice of Substrate Selected Results from Growth of AlGaN Layers by HVPE Summary 70 References 70 4 Growth Techniques of AIN/AlGaN and Development of High-Efficiency Deep-Ultraviolet Light-Emitting Diodes 75 Hideki Hirayama 4.1 Introduction Research Background of DUV LEDs Growth Techniques of High-Quality A1N on Sapphire Substrate Marked Increase in Internal Quantum Efficiency (IQE) nm AlGaN and InAlGaN DUV LEDs Increase in Electron Injection Efficiency (EIE) by MQB Future LED Design for Obtaining High Light Extraction Efficiency (LEE) Summary Ill References Impacts of Dislocations and Point Defects on the Internal Quantum Efficiency of the Near-Band-Edge Emission in AlGaN-Based DUV Light-Emitting Materials 115 Shigefusa F. Chichibu, Hideto Miyake, Kazumasa Hiramtsu and Akira Uedono 5.1 Introduction Experimental Details Impacts of Impurities and Point Defects on the Near-Band-Edge Luminescence Dynamics of A1N Effective Radiative Lifetime of the Near-Band-Edge Emission in Al/ja^N Films 125

4 Contents xi 5.5 Impacts of Si-Doping and Resultant Cation Vacancy Formation on the Luminescence Dynamics of the Near-Band-Edge Emission in Alo.6Gao.4N Films Grown on A1N Templates Summary 133 References Optical Polarization and Light Extraction from UV LEDs 137 Jens Rass and Neysha Lobo-Ploch 6.1 Light Extraction from UV LEDs Optical Polarization Factors Influencing the Light Polarization Switching in AlGaN Layers Optical Polarization Dependence on Substrate Orientation Influence of the Optical Polarization on the Light Extraction Efficiency Concepts for Improved Light Extraction Contact Materials and Design Surface Preparation Packaging 164 References Fabrication of High Performance UVC LEDs on Aluminum-Nitride Semiconductor Substrates and Their Potential Application in Point-of-Use Water Disinfection Systems 171 James R. Grandusky, Rajul V. Randive, Therese C. Jordan and Leo J. Schowalter 7.1 Introduction Types of UVC Light Sources What Is UVC Light? How Does Germicidal UV Work Fabrication of UVC LEDs on A1N Substrates Leveraging Performance Gains in UVC LEDs for POU Water Disinfection Effect of UVT Design Flexibility Modeling Flow Cells Example Flow Analysis Working with UVC Light 189 References 191

5 xii Contents... 8 AlGaN-Based Ultraviolet Laser Diodes 193 Thomas Wunderer, John E. Northrup and Noble M. Johnson 8.1 Introduction Growth on Bulk A1N for Highest Material Quality Bulk A1N Substrate Homoepitaxial A1N AlGaN Laser Heterostructure Multiple Quantum Well Active Zone High Current Capability in High Band Gap AlGaN Materials High Injection Efficiency at High Current Levels Optically Pumped UV Lasers Alternative Concepts for Compact Deep-UV UI-N Lasers Electron-Beam Pumped Laser InGaN-Based VECSEL + Second Harmonic Generation Summary and Conclusion 214 References Solar- and Visible-Blind AlGaN Photodetectors 219 Moritz Brendel, Enrico Pertzsch, Vera Abrosimova, Torsten Trenkler and Markus Weyers 9.1 Introduction Basics of Photodetectors Characteristic Parameters and Phenomena Various Types of Semiconductor Photodetectors m-nitrides for Solid-State UV Photodetection AlGaN-Based Photoconductor AlGaN-Based MSM Photodetector AlGaN-Based Schottky Barrier Photodiode AlGaN-Based p-i-n Photodiode AlGaN-Based Avalanche Photodetector AlGaN-Based Photocathode UI-Nitride-Based Devices of High Integration Level Present Status of Wide Bandgap Photodetectors Summary and Conclusions 257 References Ultraviolet Light-Emitting Diodes for Water Disinfection 267 Martina A. Lange, Tim Kolbe and Martin Jekel 10.1 Introduction Basic Principles of UV Disinfection Factors Influencing UV Fluence 271

6 Contents xiii Modeling and Validation of UV Reactor Performance Case Study Proposal for an Experimental Setup to Test UV LEDs Test Conditions Results of Tests Conducted with UV LEDs Potential of UV LEDs for Water Disinfection 287 References Application of UV Emitters in Dermatological Phototherapy 293 Uwe Wollina, Bernd Seme, Armin Scheibe and Emmanuel Gutmann 11.1 Introduction Sources for UV Phototherapy Natural Sunlight Gas Discharge Lamps Lasers UV-LEDs Variants of Dermatological UV Phototherapy Psoralen Plus UVA (PUVA) Therapy Broadband UVB (BB-UVB) Therapy Narrowband UVB (NB-UVB) Therapy UVA-1 Therapy Targeted UV Phototherapy Extracorporeal Photochemotherapy (ECP) Mechanisms of Action for Major Dermatological Indications Psoriasis Atopic Dermatitis Vitiligo Cutaneous T-Cell Lymphomas Lichen Planus and Alopecia Areata Systemic Sclerosis and Morphoea Graft-Versus-Host Disease Polymorphic Light Eruption Clinical Studies with Novel UV Emitters Study with an Electrodeless Excimer Lamp Study with UV-LEDs Summary and Outlook 313 References 314

7 xiv Contents 12 UV Emitters in Gas Sensing Applications 321 Martin Degner and Hartmut Ewald 12.1 Introduction Light Absorption Spectroscopy Absorption Spectroscopic Systems Light Sources for UV Spectroscopy Optical and Electrical Properties of the LEDs for Spectroscopy Application Application of UV-LED Absorption Spectroscopy Ozone Sensor Ozone Sensor Design Measurement Arrangement Results S02 and N02 Sensor Sensor Design for S02/N02 Exhaust Gas Sensor Measurement Setup Conclusion and Outlook 348 References UV Fluorescence Detection and Spectroscopy in Chemistry and Life Sciences 351 Emmanuel Gutmann, Florian Erfurth, Anke Drewitz, Armin Scheibe and Martina C. Meinke 13.1 Introduction Fundamentals and Apparative Aspects of Fluorescence Detection and Spectroscopy Fluorescence in Lab-Based Instrumental Analysis Fluorescence Chemical Sensing for Environmental Monitoring and Bioanalytics Detection of Microorganisms Using Autofluorescence Fluorescence in Medical Diagnosis of Skin Diseases Summary and Outlook 378 References UV-B Elicitation of Secondary Plant Metabolites 387 Monika Schreiner, Inga Mewis, Susanne Neugart, Rita Zrenner, Johannes Glaab, Melanie Wiesner and Marcel A.K. Jansen 14.1 Nature and Occurrence of Secondary Plant Metabolites Nutritional Physiology of Secondary Plant Metabolites Association Between Fruit and Vegetable Consumption and Chronic Diseases Secondary Plant Metabolites Within the Plant-Environment Interaction UV-B Perception and Signaling in the Plant 391

8 Contents xv UV-B as Stressor and Plant Regulator Structure-Differentiated Response to UV-B Flavonoids and Other Phenolics Glucosinolates Tailor-Made UV-B Induction of Secondary Plant Metabolites by UV-B LEDs Current State of Research: UV-B Light-Emitting Diodes for Plant Lightning Advantages of UV-B LEDs for Targeted Triggering of Plant Properties Experimental Setup for Targeted Triggering of Plant Properties by UV-B LEDs Outlook 405 References Application of LEDs for UV-Curing 415 Christian Dreyer and Franziska Mildner 15.1 Introduction Light Source Chemistry and Mechanisms Kinetics Medical Applications Coatings, Inks, and Printing Stereolithography Conclusion and Outlook 431 References 432 Index 435