Aln Base Layers For Uv Leds

To enable the fabrication of high performance ultraviolet (UV) light-emitting diodes (LEDs) this work aims at improving the quality of AlN base layers on sapphire substrates. The main issues for UV LEDs are still a limited internal quantum efficiency due to a high amount of threading dislocations along with a limited light extraction efficiency due to total internal reflection at the AlN/sapphire interface. Therefore, high-temperature annealing of AlN/sapphire layers and growth on nanopatterned sapphire substrates were comprehensively investigated. High-temperature annealing was applied to AlN layers of different strain and thickness grown by metalorganic vapour phase epitaxy (MOVPE). The threading dislocation density could be successfully reduced by more than one order of magnitude down to 6 × 108 cm-2. Wave optical simulations of UV LEDs on nanopatterned sapphire substrates (NPSS) were conducted and showed a potential increase in light extraction efficiency compared to a planar substrate. The optimized MOVPE growth process on sapphire nanopillars and sapphire nanoholes resulted in a fully coalesced and atomically smooth AlN surface. The threading dislocation density was reduced to 1 ×109 cm-2 for AlN on both nanopillars and nanoholes. UVC LEDs emitting at 265 nm wavelength were grown on top of the developed templates. Increased internal efficiency was obtained by reduced dislocation density and more efficient light extraction was achieved on NPSS in case of a transparent heterostructure and reflective contacts. Thus, the developed templates yield considerable improvement in light output compared to conventional templates.

This book provides a comprehensive overview of the state-of-the-art in group III-nitride based ultraviolet LED and laser technologies, covering different substrate approaches, a review of optical, electronic and structural properties of InAlGaN materials as well as various optoelectronic components. In addition, the book gives an overview of a number of key application areas for UV emitters and detectors, including water purification, phototherapy, sensing, and UV curing. The book is written for researchers and graduate level students in the area of semiconductor materials, optoelectronics and devices as well as developers and engineers in the various application fields of UV emitters and detectors.

Ultrawide Bandgap Semiconductors, Volume 107 in the Semiconductors and Semimetals series, highlights the latest breakthrough in fundamental science and technology development of ultrawide bandgap (UWBG) semiconductor materials and devices based on gallium oxide, aluminium nitride, boron nitride, and diamond. It includes important topics on the materials growth, characterization, and device applications of UWBG materials, where electronic, photonic, thermal and quantum properties are all thoroughly explored. Contains the latest breakthrough in fundamental science and technology development of ultrawide bandgap (UWBG) semiconductor materials and devices Provides a comprehensive presentation that covers the fundamentals of materials growth and characterization, as well as design and performance characterization of state-of-the-art UWBG materials, structures, and devices Presents an in-depth discussion on electronic, photonic, thermal, and quantum technologies based on UWBG materials

This handbook addresses the development of energy-efficient, environmentally friendly solid-state light sources, in particular semiconductor light emitting diodes (LEDs) and other solid-state lighting devices. It reflects the vast growth of this field and impacts in diverse industries, from lighting to communications, biotechnology, imaging, and medicine. The chapters include coverage of nanoscale processing, fabrication of LEDs, light diodes, photodetectors and nanodevices, characterization techniques, application, and recent advances. Readers will obtain an understanding of the key properties of solid-state lighting and LED devices, an overview of current technologies, and appreciation for the challenges remaining. The handbook will be useful to material growers and evaluators, device design and processing engineers, newcomers, students, and professionals in the field.

Comprehensive in scope, this book covers the latest progresses of theories, technologies and applications of LEDs based on III-V semiconductor materials, such as basic material physics, key device issues (homoepitaxy and heteroepitaxy of the materials on different substrates, quantum efficiency and novel structures, and more), packaging, and system integration. The authors describe the latest developments of LEDs with spectra coverage from ultra-violet (UV) to the entire visible light wavelength. The major aspects of LEDs, such as material growth, chip structure, packaging, and reliability are covered, as well as emerging and novel applications beyond the general and conventional lightings. This book, written by leading authorities in the field, is indispensable reading for researchers and students working with semiconductors, optoelectronics, and optics. Addresses novel LED applications such as LEDs for healthcare and wellbeing, horticulture, and animal breeding; Editor and chapter authors are global leading experts from the scientific and industry communities, and their latest research findings and achievements are included; Foreword by Hiroshi Amano, one of the 2014 winners of the Nobel Prize in Physics for his work on light-emitting diodes.

In modern research and development, materials manufacturing crystal growth is known as a way to solve a wide range of technological tasks in the fabrication of materials with preset properties. This book allows a reader to gain insight into selected aspects of the field, including growth of bulk inorganic crystals, preparation of thin films, low-dimensional structures, crystallization of proteins, and other organic compounds.

In recent years the field of semiconductor optics has been pushed to several extremes. The size of semiconductor structures has shrunk to dimensions of a few nanometers, the semiconductor-light interaction is studied on timescales as fast as a few femtoseconds, and transport properties on a length scale far below the wavelength of light have been revealed. These advances were driven by rapid improvements in both semiconductor and optical technologies and were further facilitated by progress in the theoretical description of optical excitations in semiconductors. This book, written by leading experts in the field, provides an up-to-date introduction to the optics of semiconductors and their nanostructures so as to help the reader understand these exciting new developments. It also discusses recently established applications, such as blue-light emitters, as well as the quest for future applications in areas such as spintronics, quantum information processing, and third-generation solar cells.

Materials for Energy offers a comprehensive overview of the latest developments in materials for efficient and sustainable energy applications, including energy conversion, storage, and smart applications. Discusses a wide range of material types, such as nanomaterials, carbonaceous electrocatalysts and electrolytes, thin films, phase change materials, 2D energy materials, triboelectric materials, and membrane materials Describes applications that include flexible energy storage devices, sensors, energy storage batteries, fuel and solar cells, photocatalytic wastewater treatment, and more Highlights current developments in energy conversion, storage, and applications from a materials angle Aimed at researchers, engineers, and technologists working to solve alternative energy issues, this work illustrates the state of the art and latest technologies in this important field.

The book provides an overview of III-nitride-material-based light-emitting diode (LED) technology, from the basic material physics to the latest advances in the field, such as homoepitaxy and heteroepitaxy of the materials on different substrates. It also includes the latest advances in the field, such as approaches to improve quantum efficiency and reliability as well as novel structured LEDs. It explores the concept of material growth, chip structure, packaging, reliability and application of LEDs. With spectra coverage from ultraviolet (UV) to entire visible light wavelength, the III-nitride-material-based LEDs have a broad application potential, and are not just limited to illumination. These novel applications, such as health & medical, visible light communications, fishery and horticulture, are also discussed in the book.

III-Nitride Semiconductor Optoelectronics covers the latest breakthrough research and exciting developments in the field of III-nitride compound semiconductors. It includes important topics on the fundamentals of materials growth, characterization, and optoelectronic device applications of III-nitrides. Bulk, quantum well, quantum dot, and nanowire heterostructures are all thoroughly explored. Contains the latest breakthrough research in III-nitride optoelectronics Provides a comprehensive presentation that covers the fundamentals of materials growth and characterization and the design and performance characterization of state-of-the-art optoelectronic devices Presents an in-depth discussion on III-nitride bulk, quantum well, quantum dot, and nanowire technologies