Springer Series in Materials Science 227

Michael KneisslJens Rass Editors

III-Nitride Ultraviolet EmittersTechnology and Applications

Springer Series in Materials Science

Volume 227

Series editors

Robert Hull, Charlottesville, USAChennupati Jagadish, Canberra, AustraliaRichard M. Osgood, New York, USAJürgen Parisi, Oldenburg, GermanyTae-Yeon Seong, Seoul, Korea, Republic of (South Korea)Shin-ichi Uchida, Tokyo, JapanZhiming M. Wang, Chengdu, ChinaYoshiyuki Kawazoe, Sendai, Japan

The Springer Series in Materials Science covers the complete spectrum ofmaterials physics, including fundamental principles, physical properties, materialstheory and design. Recognizing the increasing importance of materials science infuture device technologies, the book titles in this series reflect the state-of-the-artin understanding and controlling the structure and properties of all importantclasses of materials.

More information about this series at http://www.springer.com/series/856

Michael Kneissl • Jens RassEditors

III-Nitride UltravioletEmittersTechnology and Applications

123

EditorsMichael KneisslInstitute of Solid State PhysicsTechnische Universität BerlinBerlinGermany

and

Ferdinand-Braun-InstitutLeibniz-Institut für HöchstfrequenztechnikBerlinGermany

Jens RassInstitute of Solid State PhysicsTechnische Universität BerlinBerlinGermany

and

Ferdinand-Braun-InstitutLeibniz-Institut für HöchstfrequenztechnikBerlinGermany

ISSN 0933-033X ISSN 2196-2812 (electronic)Springer Series in Materials ScienceISBN 978-3-319-24098-5 ISBN 978-3-319-24100-5 (eBook)DOI 10.1007/978-3-319-24100-5

Library of Congress Control Number: 2015952531

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Preface

In the past two decades, group III-nitride-based ultraviolet light-emitting diodes(UV-LEDs) and their applications have undergone a progressively acceleratingdevelopment. This can be demonstrated by many metrics. For example, the numberof published articles in the area of UV-LEDs is steadily increasing and has reachednearly 1.000 journal articles per year in 2014 (see Fig. 1). However, we have foundthat the fast progress in this field makes it difficult to obtain or maintain a com-prehensive overview of all these very rapidly developing research areas. Manytimes when researchers in the field of semiconductor materials and optoelectronicsdevices describe the applications of UV emitters, large gaps in information arerevealed. On the other hand, developers and engineers who are working in variousareas of applications of UV emitters and detectors often do not comprehend thecomplexities in materials and device development. In order to put all thesedevelopments into a context, various chapters in this book aim to provide a com-prehensive examination of the state of the art in group III-nitride-based materials,ultraviolet emitters, and their applications. It is intended for researchers andgraduate-level students in the area of electrical engineering, material science, andphysics as well as scientists, developers, and engineers in various application fieldsof UV emitters and detectors. The book provides an overview of group III-nitridematerials including their structural, optical, and electronic properties as well as key

Fig. 1 Journal articles ineach year for publicationsunder the keywords “ultravi-olet” and “light emittingdiode” (Source Web ofScience. Retrieved 17 July2015 from apps.webofknowledge.com)

v

features of various optoelectronic components, like UV-LEDs, ultraviolet lasers,and photodetectors. It also offers an introduction to a number of key applications forUV emitters and detectors, including water purification, phototherapy, gas sensing,fluorescence excitation, plant growth lighting, and UV curing. Although eachchapter stands on its own and can be understood without the knowledge of theothers, the organization of the chapters has been deliberately chosen to start withchapters focusing on basic materials properties, followed by chapters on ultravioletdevices, and to conclude with several chapters describing key applications for UVemitters and detectors. In the first chapter, Michael Kneissl provides an introductionto group III-nitride UV emitter technologies and their applications. This is followedby Matthias Bickermann’s review of the growth and structural properties of bulkAlN substrates. In the third chapter, Eberhard Richter, Sylvia Hagedorn, ArneKnauer, and Markus Weyers review the use of sapphire as a substrate fornitride-based light emitters in the UV range, especially the growth of low defectdensity AlGaN templates by hydride vapor phase epitaxy. In Chap. 4 HidekiHirayama discusses crystal growth techniques for low defect density AlN andAlGaN layers on sapphire and presents state-of-the-art performance characteristicof UVC-LEDs on sapphire. In Chap. 5 Shigefusa F. Chichibu, Hideto Miyake,Kazumasa Hiramatsu, and Akira Uedono provide an in-depth discussion of theeffects of dislocations and point defects on the internal quantum efficiency of thenear-band-edge emission in AlGaN-based DUV light-emitting materials.Understanding the role of defects on the IQE of UV-LEDs is critical for improvingthe efficiency and output power of UV-LEDs. In the area of devices, the opticalpolarization and light extraction from UV-LEDs is reviewed by Jens Rass andNeysha Lobo-Ploch. The homoepitaxial growth of UVC-LEDs on bulk AlN sub-strates and their application in water disinfection is examined by James R.Grandusky, Rajul V. Randive, Therese C. Jordan, and Leo J. Schowalter in Chap. 7.Noble Johnson, John Northrup, and Thomas Wunderer discuss optical gain inAlGaN quantum well laser heterostructures and present the state of the art in thedevelopment of AlGaN-based UV laser diodes in Chap. 8, and in Chap. 9 solar andvisible blind UV photodetectors are reviewed by Moritz Brendel, Enrico Pertzsch,Vera Abrosimova, and Torsten Trenkler. In Chap. 10 Marlene Lange, Tim Kolbe,and Martin Jekel examine the application of UVC-LEDs for water purification andin Chap. 11 Uwe Wollina, Bernd Seme, Armin Scheibe, and Emmanuel Gutmanndescribe the application of UV emitters in dermatological phototherapy. In Chap.12 Hartmut Ewald and Martin Degner review the role of UV emitters in gas-sensingapplications and in Chap. 13 Emmanuel Gutmann, Florian Erfurth, Anke Drewitz,Armin Scheibe, and Martina Meinke discuss UV fluorescence detection andspectroscopy systems for applications in chemistry and life sciences. In Chap. 14Monika Schreiner, Inga Mewis, Susanne Neugart, Rita Zrenner, Melanie Wiesner,Johannes Glaab, and M.A.K. Jansen examine the application of UV-LEDs for plantgrowth lighting, especially the triggering of the secondary plant metabolism withUVB light. In the final chapter, the application of LEDs for UV curing is reviewedby Carsten Dreyer and Franziska Mildner.

vi Preface

We like to thank all the authors of the various chapters for their timely andwell-prepared contributions. This book would not have been possible without theircommitment, hard work, and perseverance. We would especially like to thankClaus Ascheron at Springer Science for presenting us with the opportunity to editthis book and for his continued support during the process.

Berlin, Germany Michael KneisslJens Rass

Preface vii

Contents

1 A Brief Review of III-Nitride UV Emitter Technologiesand Their Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Michael Kneissl1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 UV Light Emitters and Their Applications . . . . . . . . . . . . . . . 31.3 UV-LEDs—State of the Art and the Challenges Ahead . . . . . . 41.4 UV-LEDs—Key Parameters and Device Performance . . . . . . . 71.5 The Role of Defects on the IQE of UV-LEDs . . . . . . . . . . . . 101.6 Current-Injection Efficiency and Operating Voltages

of UV-LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121.7 Light Extraction from UV-LEDs . . . . . . . . . . . . . . . . . . . . . . 131.8 Thermal Management and Degradation of UV-LED . . . . . . . . 141.9 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.10 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2 Growth and Properties of Bulk AlN Substrates . . . . . . . . . . . . . . 27Matthias Bickermann2.1 Properties and History of AlN Crystals . . . . . . . . . . . . . . . . . 272.2 AlN Bulk Growth by the PVT Method: Theory . . . . . . . . . . . 292.3 AlN Bulk Growth by the PVT Method: Technology . . . . . . . . 312.4 Seeded Growth and Crystal Enlargement . . . . . . . . . . . . . . . . 342.5 Structural Defects in PVT-Grown AlN Bulk Crystals. . . . . . . . 362.6 Impurities and Resulting Properties of AlN Substrates . . . . . . . 382.7 Conclusions and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . 41References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

ix

3 Vapor Phase Epitaxy of AlGaN Base Layers on SapphireSubstrates for Nitride-Based UV-Light Emitters. . . . . . . . . . . . . . 47Eberhard Richter, Sylvia Hagedorn, Arne Knauerand Markus Weyers3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473.2 Growth of Al(Ga)N Buffer Layers by MOVPE. . . . . . . . . . . . 493.3 Techniques for MOVPE of Al(Ga)N Base Layers

with Reduced TDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 513.4 Growth of AlGaN Layers by HVPE . . . . . . . . . . . . . . . . . . . 54

3.4.1 Fundamentals of the HVPE Technique. . . . . . . . . . . . 543.4.2 The Choice of Substrate. . . . . . . . . . . . . . . . . . . . . . 583.4.3 Selected Results from Growth of AlGaN

Layers by HVPE. . . . . . . . . . . . . . . . . . . . . . . . . . . 583.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

4 Growth Techniques of AlN/AlGaN and Developmentof High-Efficiency Deep-Ultraviolet Light-Emitting Diodes . . . . . . 75Hideki Hirayama4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 754.2 Research Background of DUV LEDs. . . . . . . . . . . . . . . . . . . 764.3 Growth Techniques of High-Quality AlN on Sapphire

Substrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814.4 Marked Increase in Internal Quantum Efficiency (IQE) . . . . . . 854.5 222–351 nm AlGaN and InAlGaN DUV LEDs . . . . . . . . . . . 904.6 Increase in Electron Injection Efficiency (EIE) by MQB . . . . . 974.7 Future LED Design for Obtaining High Light

Extraction Efficiency (LEE) . . . . . . . . . . . . . . . . . . . . . . . . . 1044.8 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

5 Impacts of Dislocations and Point Defects on the InternalQuantum Efficiency of the Near-Band-Edge Emissionin AlGaN-Based DUV Light-Emitting Materials . . . . . . . . . . . . . . 115Shigefusa F. Chichibu, Hideto Miyake, Kazumasa Hiramtsuand Akira Uedono5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1165.2 Experimental Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1185.3 Impacts of Impurities and Point Defects

on the Near-Band-Edge Luminescence Dynamics of AlN. . . . . 1205.4 Effective Radiative Lifetime of the Near-Band-Edge

Emission in AlxGa1−xN Films . . . . . . . . . . . . . . . . . . . . . . . . 125

x Contents

5.5 Impacts of Si-Doping and Resultant Cation VacancyFormation on the Luminescence Dynamicsof the Near-Band-Edge Emission in Al0.6Ga0.4N FilmsGrown on AlN Templates . . . . . . . . . . . . . . . . . . . . . . . . . . 127

5.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

6 Optical Polarization and Light Extraction from UV LEDs . . . . . . 137Jens Rass and Neysha Lobo-Ploch6.1 Light Extraction from UV LEDs . . . . . . . . . . . . . . . . . . . . . . 1386.2 Optical Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

6.2.1 Factors Influencing the Light PolarizationSwitching in AlGaN Layers . . . . . . . . . . . . . . . . . . . 143

6.2.2 Optical Polarization Dependence on SubstrateOrientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

6.2.3 Influence of the Optical Polarization on the LightExtraction Efficiency . . . . . . . . . . . . . . . . . . . . . . . . 149

6.3 Concepts for Improved Light Extraction. . . . . . . . . . . . . . . . . 1526.3.1 Contact Materials and Design . . . . . . . . . . . . . . . . . . 1526.3.2 Surface Preparation . . . . . . . . . . . . . . . . . . . . . . . . . 1576.3.3 Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

7 Fabrication of High Performance UVC LEDson Aluminum-Nitride Semiconductor Substrates and TheirPotential Application in Point-of-Use Water DisinfectionSystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171James R. Grandusky, Rajul V. Randive, Therese C. Jordanand Leo J. Schowalter7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

7.1.1 Types of UVC Light Sources . . . . . . . . . . . . . . . . . . 1727.1.2 What Is UVC Light? . . . . . . . . . . . . . . . . . . . . . . . . 1737.1.3 How Does Germicidal UV Work . . . . . . . . . . . . . . . 174

7.2 Fabrication of UVC LEDs on AlN Substrates . . . . . . . . . . . . . 1757.3 Leveraging Performance Gains in UVC LEDs

for POU Water Disinfection . . . . . . . . . . . . . . . . . . . . . . . . . 1837.3.1 Effect of UVT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1837.3.2 Design Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . 1867.3.3 Modeling Flow Cells . . . . . . . . . . . . . . . . . . . . . . . . 1867.3.4 Example Flow Analysis . . . . . . . . . . . . . . . . . . . . . . 1877.3.5 Working with UVC Light . . . . . . . . . . . . . . . . . . . . 189

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

Contents xi

8 AlGaN-Based Ultraviolet Laser Diodes . . . . . . . . . . . . . . . . . . . . 193Thomas Wunderer, John E. Northrup and Noble M. Johnson8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1948.2 Growth on Bulk AlN for Highest Material Quality . . . . . . . . . 196

8.2.1 Bulk AlN Substrate . . . . . . . . . . . . . . . . . . . . . . . . . 1968.2.2 Homoepitaxial AlN . . . . . . . . . . . . . . . . . . . . . . . . . 1978.2.3 AlGaN Laser Heterostructure . . . . . . . . . . . . . . . . . . 1988.2.4 Multiple Quantum Well Active Zone . . . . . . . . . . . . . 199

8.3 High Current Capability in High Band Gap AlGaNMaterials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

8.4 High Injection Efficiency at High Current Levels . . . . . . . . . . 2058.5 Optically Pumped UV Lasers . . . . . . . . . . . . . . . . . . . . . . . . 2088.6 Alternative Concepts for Compact Deep-UV III-N Lasers . . . . 211

8.6.1 Electron-Beam Pumped Laser . . . . . . . . . . . . . . . . . . 2128.6.2 InGaN-Based VECSEL + Second Harmonic

Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2138.7 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 214References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

9 Solar- and Visible-Blind AlGaN Photodetectors . . . . . . . . . . . . . . 219Moritz Brendel, Enrico Pertzsch, Vera Abrosimova,Torsten Trenkler and Markus Weyers9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2199.2 Basics of Photodetectors . . . . . . . . . . . . . . . . . . . . . . . . . . . 222

9.2.1 Characteristic Parameters and Phenomena . . . . . . . . . 2229.2.2 Various Types of Semiconductor Photodetectors . . . . . 232

9.3 III-Nitrides for Solid-State UV Photodetection . . . . . . . . . . . . 2429.3.1 AlGaN-Based Photoconductor. . . . . . . . . . . . . . . . . . 2449.3.2 AlGaN-Based MSM Photodetector . . . . . . . . . . . . . . 2459.3.3 AlGaN-Based Schottky Barrier Photodiode. . . . . . . . . 2479.3.4 AlGaN-Based p-i-n Photodiode. . . . . . . . . . . . . . . . . 2489.3.5 AlGaN-Based Avalanche Photodetector . . . . . . . . . . . 2509.3.6 AlGaN-Based Photocathode . . . . . . . . . . . . . . . . . . . 2529.3.7 III-Nitride-Based Devices of High Integration

Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2549.4 Present Status of Wide Bandgap Photodetectors . . . . . . . . . . . 2559.5 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 257References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

10 Ultraviolet Light-Emitting Diodes for Water Disinfection . . . . . . . 267Marlene A. Lange, Tim Kolbe and Martin Jekel10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26710.2 Basic Principles of UV Disinfection . . . . . . . . . . . . . . . . . . . 268

10.2.1 Factors Influencing UV Fluence . . . . . . . . . . . . . . . . 271

xii Contents

10.2.2 Modeling and Validation of UV ReactorPerformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

10.3 Case Study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27410.3.1 Proposal for an Experimental Setup

to Test UV LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . 27510.3.2 Test Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 27810.3.3 Results of Tests Conducted with UV LEDs . . . . . . . . 282

10.4 Potential of UV LEDs for Water Disinfection . . . . . . . . . . . . . 287References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

11 Application of UV Emitters in Dermatological Phototherapy. . . . . 293Uwe Wollina, Bernd Seme, Armin Scheibeand Emmanuel Gutmann11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29311.2 Sources for UV Phototherapy . . . . . . . . . . . . . . . . . . . . . . . . 294

11.2.1 Natural Sunlight . . . . . . . . . . . . . . . . . . . . . . . . . . . 29511.2.2 Gas Discharge Lamps . . . . . . . . . . . . . . . . . . . . . . . 29611.2.3 Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29811.2.4 UV-LEDs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299

11.3 Variants of Dermatological UV Phototherapy . . . . . . . . . . . . . 30011.3.1 Psoralen Plus UVA (PUVA) Therapy . . . . . . . . . . . . 30011.3.2 Broadband UVB (BB-UVB) Therapy . . . . . . . . . . . . 30211.3.3 Narrowband UVB (NB-UVB) Therapy . . . . . . . . . . . 30211.3.4 UVA-1 Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . 30311.3.5 Targeted UV Phototherapy . . . . . . . . . . . . . . . . . . . . 30311.3.6 Extracorporeal Photochemotherapy (ECP) . . . . . . . . . 304

11.4 Mechanisms of Action for Major DermatologicalIndications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30611.4.1 Psoriasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30711.4.2 Atopic Dermatitis . . . . . . . . . . . . . . . . . . . . . . . . . . 30711.4.3 Vitiligo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30811.4.4 Cutaneous T-Cell Lymphomas . . . . . . . . . . . . . . . . . 30811.4.5 Lichen Planus and Alopecia Areata . . . . . . . . . . . . . . 30911.4.6 Systemic Sclerosis and Morphoea . . . . . . . . . . . . . . . 30911.4.7 Graft-Versus-Host Disease . . . . . . . . . . . . . . . . . . . . 30911.4.8 Polymorphic Light Eruption . . . . . . . . . . . . . . . . . . . 310

11.5 Clinical Studies with Novel UV Emitters . . . . . . . . . . . . . . . . 31011.5.1 Study with an Electrodeless Excimer Lamp . . . . . . . . 31011.5.2 Study with UV-LEDs . . . . . . . . . . . . . . . . . . . . . . . 312

11.6 Summary and Outlook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

Contents xiii

12 UV Emitters in Gas Sensing Applications . . . . . . . . . . . . . . . . . . 321Martin Degner and Hartmut Ewald12.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32112.2 Light Absorption Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . 32412.3 Absorption Spectroscopic Systems . . . . . . . . . . . . . . . . . . . . 32912.4 Light Sources for UV Spectroscopy. . . . . . . . . . . . . . . . . . . . 33312.5 Optical and Electrical Properties of the LEDs

for Spectroscopy Application . . . . . . . . . . . . . . . . . . . . . . . . 33712.6 Application of UV-LED Absorption Spectroscopy. . . . . . . . . . 342

12.6.1 Ozone Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34212.6.2 Ozone Sensor Design . . . . . . . . . . . . . . . . . . . . . . . 34212.6.3 Measurement Arrangement . . . . . . . . . . . . . . . . . . . . 34312.6.4 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34312.6.5 SO2 and NO2 Sensor . . . . . . . . . . . . . . . . . . . . . . . . 34312.6.6 Sensor Design for SO2/NO2 Exhaust Gas Sensor . . . . 34412.6.7 Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . 345

12.7 Conclusion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . 348References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348

13 UV Fluorescence Detection and Spectroscopy in Chemistryand Life Sciences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351Emmanuel Gutmann, Florian Erfurth, Anke Drewitz,Armin Scheibe and Martina C. Meinke13.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35113.2 Fundamentals and Apparative Aspects of Fluorescence

Detection and Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . 35313.3 Fluorescence in Lab-Based Instrumental Analysis . . . . . . . . . . 35913.4 Fluorescence Chemical Sensing for Environmental

Monitoring and Bioanalytics. . . . . . . . . . . . . . . . . . . . . . . . . 36113.5 Detection of Microorganisms Using Autofluorescence . . . . . . . 36913.6 Fluorescence in Medical Diagnosis of Skin Diseases . . . . . . . . 37413.7 Summary and Outlook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378

14 UV-B Elicitation of Secondary Plant Metabolites . . . . . . . . . . . . . 387Monika Schreiner, Inga Mewis, Susanne Neugart, Rita Zrenner,Johannes Glaab, Melanie Wiesner and Marcel A.K. Jansen14.1 Nature and Occurrence of Secondary Plant Metabolites . . . . . . 38814.2 Nutritional Physiology of Secondary Plant Metabolites . . . . . . 38914.3 Association Between Fruit and Vegetable Consumption

and Chronic Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39014.4 Secondary Plant Metabolites Within the Plant–Environment

Interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39114.4.1 UV-B Perception and Signaling in the Plant . . . . . . . . 391

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14.4.2 UV-B as Stressor and Plant Regulator . . . . . . . . . . . . 39314.5 Structure-Differentiated Response to UV-B . . . . . . . . . . . . . . 394

14.5.1 Flavonoids and Other Phenolics . . . . . . . . . . . . . . . . 39514.5.2 Glucosinolates . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399

14.6 Tailor-Made UV-B Induction of Secondary PlantMetabolites by UV-B LEDs . . . . . . . . . . . . . . . . . . . . . . . . . 40214.6.1 Current State of Research: UV-B Light-Emitting

Diodes for Plant Lightning . . . . . . . . . . . . . . . . . . . . 40214.6.2 Advantages of UV-B LEDs for Targeted Triggering

of Plant Properties. . . . . . . . . . . . . . . . . . . . . . . . . . 40214.6.3 Experimental Setup for Targeted Triggering

of Plant Properties by UV-B LEDs . . . . . . . . . . . . . . 40414.7 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406

15 Application of LEDs for UV-Curing . . . . . . . . . . . . . . . . . . . . . . 415Christian Dreyer and Franziska Mildner15.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41515.2 Light Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41715.3 Chemistry and Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . 41915.4 Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42215.5 Medical Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42415.6 Coatings, Inks, and Printing . . . . . . . . . . . . . . . . . . . . . . . . . 42715.7 Stereolithography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43015.8 Conclusion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . 431References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432

Erratum to: Ultraviolet Light-Emitting Diodesfor Water Disinfection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E1Marlene A. Lange, Tim Kolbe and Martin Jekel

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435

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