Nitride Semiconductor Light-Emitting Diodes (LEDs)
Materials, Technologies and Applications
Woodhead Publishing Series in Electronic and Optical Materials Series

The development of nitride-based light-emitting diodes (LEDs) has led to advancements in high-brightness LED technology for solid-state lighting, handheld electronics, and advanced bioengineering applications. Nitride Semiconductor Light-Emitting Diodes (LEDs) reviews the fabrication, performance, and applications of this technology that encompass the state-of-the-art material and device development, and practical nitride-based LED design considerations.

Part one reviews the fabrication of nitride semiconductor LEDs. Chapters cover molecular beam epitaxy (MBE) growth of nitride semiconductors, modern metalorganic chemical vapor deposition (MOCVD) techniques and the growth of nitride-based materials, and gallium nitride (GaN)-on-sapphire and GaN-on-silicon technologies for LEDs. Nanostructured, non-polar and semi-polar nitride-based LEDs, as well as phosphor-coated nitride LEDs, are also discussed. Part two covers the performance of nitride LEDs, including photonic crystal LEDs, surface plasmon enhanced LEDs, color tuneable LEDs, and LEDs based on quantum wells and quantum dots. Further chapters discuss the development of LED encapsulation technology and the fundamental efficiency droop issues in gallium indium nitride (GaInN) LEDs. Finally, part three highlights applications of nitride LEDs, including liquid crystal display (LCD) backlighting, infrared emitters, and automotive lighting.

Nitride Semiconductor Light-Emitting Diodes (LEDs) is a technical resource for academics, physicists, materials scientists, electrical engineers, and those working in the lighting, consumer electronics, automotive, aviation, and communications sectors.

• Contributor contact details
• Woodhead Publishing Series in Electronic and Optical Materials
• Dedication
• Preface
• Part I: Materials and fabrication
  • 1: Molecular beam epitaxy (MBE) growth of nitride semiconductors
    • Abstract
    • 1.1 Introduction
    • 1.2 Molecular beam epitaxial (MBE) growth techniques
    • 1.3 Plasma-assisted MBE (PAMBE) growth of nitride epilayers and quantum structures
    • 1.4 Nitride nanocolumn (NC) materials
    • 1.5 Nitride nanostructures based on NCs
    • 1.6 Conclusion
  • 2: Modern metal-organic chemical vapor deposition (MOCVD) reactors and growing nitride-based materials
    • Abstract
    • 2.1 Introduction
    • 2.2 MOCVD systems
    • 2.3 Planetary reactors
    • 2.4 Close-coupled showerhead (CCS) reactors
    • 2.5 In situ monitoring systems and growing nitride-based materials
    • 2.6 Acknowledgements
  • 3: Gallium nitride (GaN) on sapphire substrates for visible LEDs
    • Abstract
    • 3.1 Introduction
    • 3.2 Sapphire substrates
    • 3.3 Strained heteroepitaxial growth on sapphire substrates
    • 3.4 Epitaxial overgrowth of GaN on sapphire substrates
    • 3.5 GaN growth on non-polar and semi-polar surfaces
    • 3.6 Future trends
  • 4: Gallium nitride (GaN) on silicon substrates for LEDs
    • Abstract
    • 4.1 Introduction
    • 4.2 An overview of gallium nitride (GaN) on silicon substrates
    • 4.3 Silicon overview
    • 4.4 Challenges for the growth of GaN on silicon substrates
    • 4.5 Buffer-layer strategies
    • 4.6 Device technologies
    • 4.7 Conclusion
  • 5: Phosphors for white LEDs
    • Abstract
    • 5.1 Introduction
    • 5.2 Optical transitions of Ce^3 + and Eu^2 +
    • 5.3 Chemical composition of representative nitride and oxynitride phosphors
    • 5.4 Compounds activated by Eu^2 +
    • 5.5 Compounds activated by Ce^3 +
    • 5.6 Features of the crystal structure of nitride and oxynitride phosphors
    • 5.7 Features of optical transitions of nitride and oxynitride phosphors
    • 5.8 Conclusion and future trends
    • 5.9 Acknowledgements
  • 6: Fabrication of nitride LEDs
    • Abstract
    • 6.1 Introduction
    • 6.2 GaN-based flip-chip LEDs and flip-chip technology
    • 6.3 GaN FCLEDs with textured micro-pillar arrays
    • 6.4 GaN FCLEDs with a geometric sapphire shaping structure
    • 6.5 GaN thin-film photonic crystal (PC) LEDs
    • 6.6 PC nano-structures and PC LEDs
    • 6.7 Light emission characteristics of GaN PC TFLEDs
    • 6.8 Conclusion
  • 7: Nanostructured LEDs
    • Abstract
    • 7.1 Introduction
    • 7.2 General mechanisms for growth of gallium nitride (GaN) related materials
    • 7.3 General characterization method
    • 7.4 Top-down technique for nanostructured LEDs
    • 7.5 Bottom-up technique for GaN nanopillar substrates prepared by molecular beam epitaxy
    • 7.6 Conclusion
  • 8: Nonpolar and semipolar LEDs
    • Abstract
    • 8.1 Motivation: limitations of conventional c-plane LEDs
    • 8.2 Introduction to selected nonpolar and semipolar planes
    • 8.3 Challenges in nonpolar and semipolar epitaxial growth
    • 8.4 Light extraction for nonpolar and semipolar LEDs
• Part II: Performance of nitride LEDs
  • 9: Efficiency droop in gallium indium nitride (GaInN)/gallium nitride (GaN) LEDs
    • Abstract
    • 9.1 Introduction
    • 9.2 Recombination models in LEDs
    • 9.3 Thermal roll-over in gallium indium nitride (GaInN) LEDs
    • 9.4 Auger recombination
    • 9.5 High-level injection and the asymmetry of carrier concentration and mobility
    • 9.6 Non-capture of carriers
    • 9.7 Polarization fields
    • 9.8 Carrier delocalization
    • 9.9 Discussion and comparison of droop mechanisms
    • 9.10 Methods for overcoming droop
  • 10: Photonic crystal nitride LEDs
    • Abstract
    • 10.1 Introduction
    • 10.2 Photonic crystal (PC) technology
    • 10.3 Improving LED extraction efficiency through PC surface patterning
    • 10.4 PC-enhanced light extraction in P-side up LEDs
    • 10.5 Modelling PC-LEDs
    • 10.6 P-side up PC-LED performance
    • 10.7 PC-enhanced light extraction in N-side up LEDs
    • 10.8 Summary
    • 10.9 Conclusions
  • 11: Surface plasmon enhanced LEDs
    • Abstract
    • 11.1 Introduction
    • 11.2 Mechanism for plasmon-coupled emission
    • 11.3 Fabrication of plasmon-coupled nanostructures
    • 11.4 Performance and outlook
    • 11.5 Acknowledgements
  • 12: Nitride LEDs based on quantum wells and quantum dots
    • Abstract
    • 12.1 Light-emitting diodes (LEDS)
    • 12.2 Polarization effects in III-nitride LEDs
    • 12.3 Current status of III-nitride LEDs
    • 12.4 Modern LED designs and enhancements
  • 13: Color tunable LEDs
    • Abstract
    • 13.1 Introduction
    • 13.2 Initial idea for stacked LEDs
    • 13.3 Second-generation LED stack with inclined sidewalls
    • 13.4 Third-generation tightly integrated chip-stacking approach
    • 13.5 Group-addressable pixelated micro-LED arrays
    • 13.6 Conclusions
  • 14: Reliability of nitride LEDs
    • Abstract
    • 14.1 Introduction
    • 14.2 Reliability testing of nitride LEDs
    • 14.3 Evaluation of LED degradation
    • 14.4 Degradation mechanisms
    • 14.5 Conclusion
  • 15: Chip packaging: encapsulation of nitride LEDs
    • Abstract
    • 15.1 Functions of LED chip packaging
    • 15.2 Basic structure of LED packaging modules
    • 15.3 Processes used in LED packaging
    • 15.4 Optical effects of gold wire bonding
    • 15.5 Optical effects of phosphor coating
    • 15.6 Optical effects of freeform lenses
    • 15.7 Thermal design and processing of LED packaging
    • 15.8 Conclusion
• Part III: Applications of nitride LEDs
  • 16: White LEDs for lighting applications: the role of standards
    • Abstract
    • 16.1 General lighting applications
    • 16.2 LED terminology
    • 16.3 Copying traditional lamps?
    • 16.4 Freedom of choice
    • 16.5 Current and future trends
  • 17: Ultraviolet LEDs
    • Abstract
    • 17.1 Research background of deep ultraviolet (DUV) LEDs
    • 17.2 Growth of low threading dislocation density (TDD) AlN layers on sapphire
    • 17.3 Marked increases in internal quantum efficiency (IQE)
    • 17.4 Aluminum gallium nitride (AlGaN)-based DUV-LEDs fabricated on high-quality aluminum nitride (AlN)
    • 17.5 Increase in electron injection efficiency (EIE) and light extraction efficiency (LEE)
    • 17.6 Conclusions and future trends
  • 18: Infrared emitters made from III-nitride semiconductors
    • Abstract
    • 18.1 Introduction
    • 18.2 High indium (In) content alloys for infrared emitters
    • 18.3 Rare-earth (RE) doped gallium nitride (GaN) emitters
    • 18.4 III-nitride materials for intersubband (ISB) optoelectronics
    • 18.5 ISB devices
    • 18.6 Conclusions
    • 18.7 Acknowledgements
  • 19: LEDs for liquid crystal display (LCD) backlighting
    • Abstract
    • 19.1 Introduction
    • 19.2 Types of LED LCD backlighting units (BLUs)
    • 19.3 Technical considerations for optical films and plates
    • 19.4 Requirements for LCD BLUs
    • 19.5 Advantages and history of LED BLUs
    • 19.6 Market trends and technological developments
    • 19.7 Optical design
  • 20: LEDs in automotive lighting
    • Abstract
    • 20.1 Introduction
    • 20.2 Forward lighting
    • 20.3 Signal lighting
    • 20.4 Human factor issues with LEDs
    • 20.5 Energy and environmental issues
    • 20.6 Future trends
    • 20.7 Sources of further information and advice
    • 20.8 Acknowledgments
• Index

• Reviews fabrication, performance, and applications of this technology that encompass the state-of-the-art material and device development, and practical nitride-based LED design considerations
• Covers the performance of nitride LEDs, including photonic crystal LEDs, surface plasmon enhanced LEDs, color tuneable LEDs, and LEDs based on quantum wells and quantum dots
• Highlights applications of nitride LEDs, including liquid crystal display (LCD) backlighting, infra-red emitters, and automotive lighting