Nitride Nanowire Light Emitting Diode

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Nitride Nanowire Light-emitting Diode

Author : Nan Guan
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (16 download)

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Book Synopsis Nitride Nanowire Light-emitting Diode by : Nan Guan

Download or read book Nitride Nanowire Light-emitting Diode written by Nan Guan and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitride nanowires exhibit outstanding opto-electronic and mechanical properties and are considered as promising materials for light-emitting diodes (LEDs), thanks to their high crystalline quality, non-polar facets, good mechanical flexibility, high aspect ratio, etc.This Ph.D. thesis addresses the growth, the device fabrication, the optical and electrical characterizations and the optical simulations of III-nitride NW devices, with a special emphasis on the LED applications.First, this thesis presents the growth of m-plane InGaN/GaN quantum wells with different In concentrations in self-assembled core-shell nanowires by metal-organic chemical vapor deposition. Then, by using these nanowires, LED devices based on two different integration strategies (namely, in-plane and vertical integration) are demonstrated.The in-plane integration is based on the horizontally dispersed single nanowires. I have proposed a basic integrated photonic platform consisting of a nanowire LED, an optimized waveguide and a nanowire photodetector. I have also developed a nanowire alignment system using dielectrophoresis.The vertical integration targets the fabrication of flexible LEDs based on vertical nanowire arrays embedded in polymer membranes. Flexible monochromatic, bi-color, white LEDs have been demonstrated. Their thermal properties have been analyzed.The nanowires grown on 2D materials by van der Waals epitaxy are easy to be lifted-off from their native substrate, which should facilitate the fabrication of flexible nanowire devices. With this motivation, in the last part of this thesis, I have investigated the selective area growth of GaN NWs on micro- and nano- scale graphene by molecular beam epitaxy.

III-nitride Nanowire Light-emitting Diodes : Design and Characterization

Author : Dipayan Datta Choudhary
Publisher :
ISBN 13 :
Total Pages : 69 pages
Book Rating : 4.:/5 (123 download)

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Book Synopsis III-nitride Nanowire Light-emitting Diodes : Design and Characterization by : Dipayan Datta Choudhary

Download or read book III-nitride Nanowire Light-emitting Diodes : Design and Characterization written by Dipayan Datta Choudhary and published by . This book was released on 2017 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: III-nitride semiconductors have been intensively studied for optoelectronic devices, due to the superb advantages offered by this materials system. The direct energy bandgap III-nitride semiconductors can absorb or emit light efficiently over a broad spectrum, ranging from 0.65 eV (InN) to 6.4 eV (AlN), which encompasses from deep ultraviolet to near infrared spectrum. However, due to the lack of native substrates, conventional III-nitride planar heterostructures generally exhibit very high dislocation densities that severely limit the device performance and reliability. On the other hand, nanowire heterostructures can be grown on lattice mismatched substrates with drastically reduced dislocation densities, due to highly effective lateral stress relaxation. Nanowire light-emitting diodes (LEDs) with emission in the ultraviolet to visible wavelength range have recently been studied for applications in solid-state lighting, flat-panel displays, and solar-blind detectors. In this thesis, investigation of the systematic process flow of design and epitaxial growth of group III-nitride nanoscale heterostructures was done. Moreover, demonstration of phosphor-free nanowire white LEDs using InGaN/AlGaN nanowire heterostructures grown directly on Si(111) substrates by molecular beam epitaxy was made. Full-color emission across nearly the entire visible wavelength range was realized by controlling the In composition in the InGaN active region. Strong white-light emission was recorded for the unpackaged nanowire LEDs with an unprecedentedly high color rendering index of 98. Moreover, LEDs with the operating wavelengths in the ultraviolet (UV) spectra, with emission wavelength in the range of 280-320 nm (UV-B) or shorter wavelength hold tremendous promise for applications in phototherapy, skin treatments, high speed dissociation and high density optical recording. Current planar AlGaN based UV-B LEDs have relatively low quantum efficiency due to their high dislocation density resulted from the large lattice mismatch between the AlGaN and suitable substrates. In this study, associated with the achievement of visible LEDs, the development of high brightness AlGaN/GaN nanowire UV-LEDs via careful design and device fabrication was shown. Strong photoluminescence spectra were recorded from these UV-B LEDs. The emission peak can be tunable from 290 nm to 320 nm by varying the Al content in AlGaN active region which can be done by optimizing the growth condition including Al/Ga flux ratio and also the growth temperature. Such visible to UV-B nanowire LEDs are ideally suited for future smart lighting, full-color display, phototherapy and skin treatments applications.

III-Nitride Based Light Emitting Diodes and Applications

Author : Tae-Yeon Seong
Publisher : Springer
ISBN 13 : 9811037558
Total Pages : 498 pages
Book Rating : 4.8/5 (11 download)

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Book Synopsis III-Nitride Based Light Emitting Diodes and Applications by : Tae-Yeon Seong

Download or read book III-Nitride Based Light Emitting Diodes and Applications written by Tae-Yeon Seong and published by Springer. This book was released on 2017-05-18 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: The revised edition of this important book presents updated and expanded coverage of light emitting diodes (LEDs) based on heteroepitaxial GaN on Si substrates, and includes new chapters on tunnel junction LEDs, green/yellow LEDs, and ultraviolet LEDs. Over the last two decades, significant progress has been made in the growth, doping and processing technologies of III-nitride based semiconductors, leading to considerable expectations for nitride semiconductors across a wide range of applications. LEDs are already used in traffic signals, signage lighting, and automotive applications, with the ultimate goal of the global replacement of traditional incandescent and fluorescent lamps, thus reducing energy consumption and cutting down on carbon-dioxide emission. However, some critical issues must be addressed to allow the further improvements required for the large-scale realization of solid-state lighting, and this book aims to provide the readers with details of some contemporary issues on which the performance of LEDs is seriously dependent. Most importantly, it describes why there must be a breakthrough in the growth of high-quality nitride semiconductor epitaxial layers with a low density of dislocations, in particular, in the growth of Al-rich and In-rich GaN-based semiconductors. The quality of materials is directly dependent on the substrates used, such as sapphire and Si, and the book discusses these as well as topics such as efficiency droop, growth in different orientations, polarization, and chip processing and packaging technologies. Offering an overview of the state of the art in III-Nitride LED science and technology, the book will be a core reference for researchers and engineers involved with the developments of solid state lighting, and required reading for students entering the field.

III-nitride Nanowire Phosphor-free White Light Emitting Diodes

Author : Shaofei Zhang
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (911 download)

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Book Synopsis III-nitride Nanowire Phosphor-free White Light Emitting Diodes by : Shaofei Zhang

Download or read book III-nitride Nanowire Phosphor-free White Light Emitting Diodes written by Shaofei Zhang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "AbstractRecently, InGaN/GaN nanowires have been intensively investigated as an alternative architecture for achieving high performance light emitting diodes (LEDs). Compared to conventional planar LED devices, they can exhibit significantly reduced dislocation densities, polarization fields and enhanced light extraction efficiency. This dissertation reports on the design, performance simulation, and characterization of nearly defect-free InGaN/GaN dot-in-wire LED heterostructures. We have developed phosphor-free white nanowire LEDs with high internal quantum efficiency and reduced efficiency droop. We have identified some of the major performance limitations of nanowire-based phosphor-free white LEDs, including poor hole transport and electron leakage/overflow. We have further demonstrated that the performance of InGaN/GaN nanowire phosphor-free white LEDs can be significantly enhanced by incorporating techniques such as p-type modulation doping and electron blocking layer (EBL) in the device active region. A detailed modeling of the device performance, including the relatively high internal quantum efficiency and reduced efficiency droop is also performed. More importantly, we have found that the dominant carrier loss mechanism in InGaN/GaN dot-in-a-wire heterostructures is surface recombination. Based on this finding, we have further developed InGaN/GaN/AlGaN dot-in-a-wire core-shell nanoscale LED heterostructures that can lead to significantly improved optical performance, due to the reduced surface recombination and enhanced carrier injection efficiency. We have also found that Joule heating effect in nanowire LED devices can be greatly enhanced by the surface recombination.This work shows that advanced nanowire heterostructures can be potentially used for applications in high power phosphor-free solid state lighting and full-color displays. It also offers critical insight for the future development of practical nanowire based photonic devices." --

Zinc Oxide and Nitride Nanowire Based Light Emitting Diodes

Author : Elaine Michelle Lai
Publisher :
ISBN 13 :
Total Pages : 218 pages
Book Rating : 4.:/5 (785 download)

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Book Synopsis Zinc Oxide and Nitride Nanowire Based Light Emitting Diodes by : Elaine Michelle Lai

Download or read book Zinc Oxide and Nitride Nanowire Based Light Emitting Diodes written by Elaine Michelle Lai and published by . This book was released on 2009 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Light emitting diodes are robust and high efficiency light sources that have the potential to replace all lighting applications in the future. Some hindrances to ubiquitous adoption of LEDs though are cost per lumen and lack of high quality materials for green emission or tunable emission. Innovations are needed to continue improving overall efficiency of light emitting diodes as well as finding suitable materials to achieve complete visible tunability. Novel light emitting diodes are made from nanoscale materials to explore potential advantages over conventional thin film approaches. These atomic-scale structures have unique electrical and optical properties that could potentially lead to increased efficiencies. Three platforms for improved light emitting diodes were designed, fabricated, and characterized. The first consisted of an n-type ZnO vertical nanowire array grown epitaxially from a p-type GaN thin film. The resulting device showed an increase of 13% in light output in the vertical direction as compared to a thin film LED due to waveguiding of light in the vertically oriented nanowires. The second device took advantage of the ability to synthesize InxGa1-xN materials in nanowire form with x greater than 30%, which would otherwise be unstable in thin film form due to phase segregation. Nanowire arrays were grown on top of conventional InGaN QW LEDs. Resulting light emission was a combination of transmitted QW blue electroluminescence and color converted photoluminescence from the array. Colors achieved ranged from blue, to blue-green, and red-orange. The final platform explored enhancement of electroluminescence by metal coating of nanopillar LEDs. The metal layer is proposed to confine light along the nanopillar and enhance radiative emission due to surface plasmons. Preliminary results suggest some extent of enhanced electroluminescence. However, fidelity of these results needs to be further explored due to concerns of light leakage through cracks in the metal layer. Nanowire based light emitting diodes were fabricated and shown to offer advantages over thin film LEDs due to waveguiding of light in the nanowire, full-spectrum tunability, and surface plasmon electroluminescent enhancement.

Light-Emitting Diodes

Author : Jinmin Li
Publisher : Springer
ISBN 13 : 3319992112
Total Pages : 601 pages
Book Rating : 4.3/5 (199 download)

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Book Synopsis Light-Emitting Diodes by : Jinmin Li

Download or read book Light-Emitting Diodes written by Jinmin Li and published by Springer. This book was released on 2019-01-07 with total page 601 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

High Efficiency III-Nitride Tunnel Junction Light-emitting Nanowire Heterostructures

Author : Sharif Sadaf
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (13 download)

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Book Synopsis High Efficiency III-Nitride Tunnel Junction Light-emitting Nanowire Heterostructures by : Sharif Sadaf

Download or read book High Efficiency III-Nitride Tunnel Junction Light-emitting Nanowire Heterostructures written by Sharif Sadaf and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The current III-nitride-based solid-state lighting technology relies on the use of a driver to convert alternating current (AC) to low-voltage direct current (DC) power, a resistive p-GaN contact layer to inject positive charge carriers (holes) for blue light emission, and phosphors to down-convert blue photons into green/red light, which have been identified as some of the major factors limiting the device efficiency, light quality, and cost. In this thesis, we demonstrated that multiple-active region phosphor-free InGaN nanowire white LEDs connected through a polarization engineered tunnel junction can fundamentally address the afore-described challenges. Such a p-GaN contact-free LED offers the benefit of carrier regeneration, leading to enhanced light intensity and reduced efficiency droop. Moreover, through the monolithic integration of p-GaN up and p-GaN down nanowire LED structures on the same substrate, we have demonstrated, for the first time, AC operated LEDs on a Si platform, which can operate efficiently in both polarity (positive and negative) of applied voltage. We have also demonstrated, for the first time, an n++-GaN/Al/p++-Al(Ga)N backward diode, wherein an epitaxial Al layer serves as the tunnel junction. The stand-alone n-p-n nanowire backward diode showed record low resistivity ~1.5×10-4 [OMEGA]. cm-2. Additionally, the monolithic metal/Al(Ga)N tunnel junction InGaN/GaN nanowire light emitting diodes (LEDs) exhibited a low turn-on voltage (~ 2.9 V), reduced resistance, and enhanced power, compared to nanowire LEDs without the use of Al tunnel junction or with the incorporation of an n++-GaN/p++-GaN tunnel junction. This unique Al tunnel junction overcomes some of the critical issues related to conventional GaN-based homo or polarization engineered tunnel junction designs, including stress relaxation, wide depletion region, and light absorption, and holds tremendous promise for realizing low resistivity, high brightness III-nitride nanowire LEDs in the visible and deep ultraviolet spectral range. Moreover, the demonstration and characterization of monolithic integration of metal and semiconductor nanowire heterojunctions provides a seamless platform for realizing a broad range of multi-functional nanoscale electronic and photonic devices. To date, semiconductor light emitting diodes (LEDs) operating in the deep ultraviolet (UV) spectral range (210-280 nm) exhibit very low efficiency, due to the presence of large densities of defects and extremely inefficient p-type conduction of conventional AlGaN quantum well heterostructures. We have demonstrated that such critical issues can be potentially addressed by using nearly defect-free AlGaN tunnel junction core-shell nanowire heterostructures. The core-shell nanowire arrays exhibit high photoluminescence efficiency (~80%) in the UV-C band at room temperature. With the incorporation of an epitaxial Al tunnel junction, the p-(Al)GaN contact-free nanowire deep UV LEDs showed nearly one order of magnitude reduction in the device resistance, compared to the conventional nanowire p-i-n device. The unpackaged Al tunnel junction deep UV LEDs (operating at ~275 nm spectral range) exhibit an output power >8 mW and a peak external quantum efficiency ~0.4%, which are nearly one to two orders of magnitude higher than previously reported AlGaN nanowire devices. We have also studied AlGaN nanowire LEDs at ~242 nm spectral range. With the use of n+-GaN/Al/p+-AlGaN tunnel junction (TJ), the device resistance is reduced by one order of magnitude and the light output power is increased by two orders of magnitude. For unpackaged TJ devices, an output power up to 0.4 mW and EQEs in the range of 0.004-0.006% are measured under pulse biasing condition. Detailed studies further suggest that the maximum achievable efficiency is limited by electron overflow and poor light extraction efficiency due to the TM polarized emission in the UV-C band." --

Control of the Emission Wavelength of Gallium Nitride-based Nanowire Light-emitting Diodes

Author : Martin Wölz
Publisher :
ISBN 13 :
Total Pages : 167 pages
Book Rating : 4.:/5 (871 download)

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Book Synopsis Control of the Emission Wavelength of Gallium Nitride-based Nanowire Light-emitting Diodes by : Martin Wölz

Download or read book Control of the Emission Wavelength of Gallium Nitride-based Nanowire Light-emitting Diodes written by Martin Wölz and published by . This book was released on 2013 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Investigation and Engineering of the Homogeneity and Current Injection of Molecular Beam Epitaxy Grown III-nitride Nanowire Ultraviolet Light Emitting Diodes

Download Investigation and Engineering of the Homogeneity and Current Injection of Molecular Beam Epitaxy Grown III-nitride Nanowire Ultraviolet Light Emitting Diodes PDF Online Free

Author : Brelon J. May
Publisher :
ISBN 13 :
Total Pages : 154 pages
Book Rating : 4.:/5 (111 download)

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Book Synopsis Investigation and Engineering of the Homogeneity and Current Injection of Molecular Beam Epitaxy Grown III-nitride Nanowire Ultraviolet Light Emitting Diodes by : Brelon J. May

Download or read book Investigation and Engineering of the Homogeneity and Current Injection of Molecular Beam Epitaxy Grown III-nitride Nanowire Ultraviolet Light Emitting Diodes written by Brelon J. May and published by . This book was released on 2019 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-assembled nanowires are attractive because of their innate ability to effectively strain relax without the creation of extended defects. This allows for interesting heteroepitaxial growths and extreme heterostructures. III-Nitride nanowires are of particular interest because of the wide range of direct bandgaps available in the material system, spanning form the infrared to the deep ultraviolet finding uses in sensors, photovoltaics, lasers and LEDs. The work presented here will be focused on nanowire LEDs with emission in the ultraviolet grown by molecular beam epitaxy. The first part of this work will discuss the possible inhomogeneities present in self-assembled nanowires and how these manifest themselves in ensemble devices. The effect of nonuniformities (specifically shorts) on the current spreading in devices where many individual diodes are wired in parallel is then addressed, and the use of a short-term-overload bias is shown as a way to reduce the presence of nonuniformities, increasing the efficiency of ensemble devices. Next, alternative substrates are investigated, with the growth of high-quality GaN nanowires being demonstrated on polycrystalline foils, the fabrication of the first UV LED grown directly on metal foil follows. The final portion of this work begins by addressing the grain-dependent uniformity issues present with growth on bulk polycrystalline foils through the use of thin nanocrystalline metal films and amorphous metals. Finally, a different nanowire LED structure is discussed in which the upper portion of the nanowires is coalesced to form a “thin-film” transparent conductive layer, enabling the substitution of the traditional fully conformal thin metal top contact with only a current spreading grid.

Nitride Semiconductor Light-Emitting Diodes (LEDs)

Author : Jian-Jang Huang
Publisher : Woodhead Publishing
ISBN 13 : 0081019432
Total Pages : 826 pages
Book Rating : 4.0/5 (81 download)

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Book Synopsis Nitride Semiconductor Light-Emitting Diodes (LEDs) by : Jian-Jang Huang

Download or read book Nitride Semiconductor Light-Emitting Diodes (LEDs) written by Jian-Jang Huang and published by Woodhead Publishing. This book was released on 2017-10-24 with total page 826 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitride Semiconductor Light-Emitting Diodes (LEDs): Materials, Technologies, and Applications, Second Edition reviews the fabrication, performance and applications of the technology, encompassing the state-of-the-art material and device development, along with considerations regarding nitride-based LED design. This updated edition is based on the latest research and advances, including two new chapters on LEDs for large displays and laser lighting. Chapters cover molecular beam epitaxy (MBE) growth of nitride semiconductors, modern metalorganic chemical vapor deposition (MOCVD) techniques, 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. The book also addresses 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 fundamental efficiency droop issues in gallium indium nitride (GaInN) LEDs. It is a technical resource for academics, physicists, materials scientists, electrical engineers, and those working in the lighting, consumer electronics, automotive, aviation, and communications sectors. Features new chapters on laser lighting, addressing the latest advances on this topic Reviews fabrication, performance, and applications of this technology that encompass the state-of-the-art material and device development 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 Provides a comprehensive discussion of gallium nitride on both silicon and sapphire substrates

Amber Light-emitting Diode Comprising a Group III-nitride Nanowire Active Region

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (946 download)

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Book Synopsis Amber Light-emitting Diode Comprising a Group III-nitride Nanowire Active Region by :

Download or read book Amber Light-emitting Diode Comprising a Group III-nitride Nanowire Active Region written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A temperature stable (color and efficiency) III-nitride based amber (585 nm) light-emitting diode is based on a novel hybrid nanowire-planar structure. The arrays of GaN nanowires enable radial InGaN/GaN quantum well LED structures with high indium content and high material quality. The high efficiency and temperature stable direct yellow and red phosphor-free emitters enable high efficiency white LEDs based on the RGYB color-mixing approach.

III-Nitrides Light Emitting Diodes: Technology and Applications

Author : Jinmin Li
Publisher : Springer Nature
ISBN 13 : 9811579490
Total Pages : 295 pages
Book Rating : 4.8/5 (115 download)

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Book Synopsis III-Nitrides Light Emitting Diodes: Technology and Applications by : Jinmin Li

Download or read book III-Nitrides Light Emitting Diodes: Technology and Applications written by Jinmin Li and published by Springer Nature. This book was released on 2020-08-31 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Nanostructuring for Nitride Light-Emitting Diodes and Optical Cavities

Author : Kwai Hei Li
Publisher : Springer
ISBN 13 : 3662486091
Total Pages : 118 pages
Book Rating : 4.6/5 (624 download)

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Book Synopsis Nanostructuring for Nitride Light-Emitting Diodes and Optical Cavities by : Kwai Hei Li

Download or read book Nanostructuring for Nitride Light-Emitting Diodes and Optical Cavities written by Kwai Hei Li and published by Springer. This book was released on 2015-12-08 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the design and fabrication of novel nanostructures in III-nitride material systems. It introduces an inexpensive and ultra-efficient nanopatterning method – nanosphere lithography (NSL) – used to develop diversely functional nanostructures, including clover-shaped photonic crystals, nanorings, and nanolenses. Furthermore, the research findings previously distributed in various international scientific journals and conference papers are brought together and methodically presented in a unified form. The book is of interest to postgraduate students, university researchers, R&D engineers and scientists in the fields of nanoelectronics, optoelectronics and photonics.

III-Nitride Nanowire Heterostructures

Author : Huy Binh Le
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (979 download)

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Book Synopsis III-Nitride Nanowire Heterostructures by : Huy Binh Le

Download or read book III-Nitride Nanowire Heterostructures written by Huy Binh Le and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The molecular beam epitaxy growth, fabrication, characterization and device applications of III-nitride nanowire heterostructures on Si (111) are presented in this dissertation. By improving the epitaxial growth process, we have achieved, for the first time, p-type conduction of InN. We report on the observation of ambipolar transport characteristics of InN:Mg nanowires at room-temperature, providing unambiguous evidence that the Fermi level is fundamentally unpinned on the grown surfaces of InN. Furthermore, our work suggests that defects and the incorporation of impurities on the grown surfaces of InN are the primary causes of the commonly measured accumulation of electrons and Fermi-level pinning. We also report on the achievement of electroluminescence emission of single InN p-i-n nanowire light emitting diodes (LEDs). Electroluminescence emission with a peak energy of 0.71 eV (1.75 [mu]m) was observed at 77 K. The measurement of near-bandgap electroluminescence provides unambiguous evidence for the achievement of p-type conduction of InN.We have demonstrated the selective area epitaxial growth (SAG) of AlxGa1-xN nanowire arrays using Ti mask. We show that the luminescence peak emission of the AlGaN nanowires grown by SAG technique can be tuned from 327 nm to 210 nm. The AlGaN deep ultraviolet (DUV) LEDs operating at 279 nm exhibit excellent optical and electrical performance, including an internal quantum efficiency (IQE) of ~45% at room-temperature and a light output power of ~3.5 W/cm2 at an injection current of 500 A/cm2. By further exploiting the advantages of SAG AlxGa1-xN nanowire arrays, we have also demonstrated that nearly dislocation-free semipolar AlGaN templates can be achieved on c-plane sapphire substrate through controlled nanowire coalescence by selective-area epitaxy. The coalesced Mg-doped AlGaN layers exhibit superior charge carrier transport properties, including a free hole concentration of ~7.4×10^18 cm-3 and mobility ~8.85 cm2/V·s at room-temperature. The semipolar AlGaN UV LEDs demonstrate excellent optical and electrical performance, including an IQE of ~83% at room-temperature and a device turn-on voltage of ~3.3 V. This work establishes the use of engineered nanowire structures as a viable architecture to achieve large-area, dislocation-free planar photonic and electronic devices. This unique concept will also enable the scaled up manufacturing of large-area, low-cost semipolar/nonpolar GaN and/or AlN templates/substrates. We also report on the demonstration of GaN/AlGaN nanowire edge emitting lasers operating in the UV spectral range. The nanowire heterostructures were monolithically grown on sapphire substrate using a selective area growth process. The nanowire lasers exhibited an ultralow threshold current of ~10.6 mA at room-temperature under continuous wave operation. This work provides a viable approach for achieving conventional edge emitting lasers by using nearly dislocation-free nanowire structures, thereby offering a new avenue for achieving ultralow threshold ultraviolet lasers that were not previously possible." --

Light Extraction Efficiency of Nanostructured III-nitride Light Emitting Diodes

Author : Yu Kee Ooi
Publisher :
ISBN 13 :
Total Pages : 149 pages
Book Rating : 4.:/5 (114 download)

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Book Synopsis Light Extraction Efficiency of Nanostructured III-nitride Light Emitting Diodes by : Yu Kee Ooi

Download or read book Light Extraction Efficiency of Nanostructured III-nitride Light Emitting Diodes written by Yu Kee Ooi and published by . This book was released on 2019 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: "III-nitride materials have been extensively employed in a wide variety of applications attributed to their compact sizes, lower operating voltage, higher energy efficiency and longer lifetime. Although tremendous progress has been reported for III-nitride light-emitting diodes (LEDs), further enhancement in the external quantum effciency ([eta]_EQE), which depends upon internal quantum efficiency, injection efficiency and light extraction efficiency ([eta]_extraction), is essential in realizing next generation high-efficiency ultraviolet (UV) and visible LEDs. Several challenges such as charge separation issue, large threading dislocation density, large refractive index contrast between GaN and air, and anisotropic emission at high Al-composition AlGaN quantum wells in the deep-UV regime have been identified to obstruct the realization of high-brightness LEDs. As a result, novel LED designs and growth methods are highly demanded to address those issues. The objective of this dissertation is to investigate the enhancement of [eta]_extraction for various nanostructured III-nitride LEDs. In the first part, comprehensive studies on the polarization-dependent [eta]_extraction for AlGaN-based flip-chip UV LEDs with microdome-shaped patterned sapphire substrates (PSS) and AlGaN-based nanowire UV LEDs are presented. Results show that the microdome-shaped PSS acts as an extractor for transverse-magnetic (TM)-polarized light where up to ~11.2-times and ~2.6-times improvement in TM-polarized [eta]_extraction can be achieved for 230 nm and 280 nm flip-chip UV LEDs, while as a reflector that limits the extraction of transverse-electric (TE)-polarized light through the sapphire substrate. Analysis for 230 nm UV LEDs with nanowire structure shows up to ~48% TM-polarized [eta]_extraction and ~41% TE-polarized [eta]_extraction as compared to the conventional planar structure (~0.2% for TM-polarized [eta]_extraction and ~2% for TE-polarized [eta]_extraction). Plasmonic green LEDs with nanowire structure have also been investigated for enhancing the LED performance via surface plasmon polaritons. The analysis shows that both [eta]_extraction and Purcell factor for the investigated plasmonic nanowire LEDs are independent of the Ag cladding layer thickness (H_Ag), where a Purcell factor of ~80 and [eta]_extraction of ~65% can be achieved when H_Ag > 60 nm. Nanosphere lithography and KOH-based wet etching process have been developed for the top-down fabrication of III-nitride nanowire LEDs. The second part of this dissertation focuses on alternative approaches to fabricate white LEDs. The integration of three-dimensional (3D) printing technology with LED fabrication is proposed as a straightforward and highly reproducible method to improve [eta[_extraction at the same time to achieve stable white color emission. The use of optically transparent acrylate-based photopolymer with a refractive index of ~1.5 as 3D printed lens on blue LED has exhibited 9% enhancement in the output power at current injection of 4 mA as compared to blue LED without 3D printed lens. Stable white color emission can be achieved with chromaticity coordinates around (0.27, 0.32) and correlated color temperature ~8900 K at current injection of 10 mA by mixing phosphor powder in the 3D printed lens. Novel LED structures employing ternary InGaN substrates are then discussed for realizing high-efficiency monolithic tunable white LEDs. Results show that large output power (~170 mW), high [eta]_EQE (~50%), chromaticity coordinates around (0.30, 0.28), and correlated color temperature ~8200 K can be achieved by engineering the band structures of the InGaN/InGaN LEDs on ternary InGaN substrates."--Abstract.

III-Nitride Semiconductor Optoelectronics

Author :
Publisher : Academic Press
ISBN 13 : 012809723X
Total Pages : 490 pages
Book Rating : 4.1/5 (28 download)

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Book Synopsis III-Nitride Semiconductor Optoelectronics by :

Download or read book III-Nitride Semiconductor Optoelectronics written by and published by Academic Press. This book was released on 2017-01-05 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

III-Nitride LEDs

Author : Shengjun Zhou
Publisher : Springer Nature
ISBN 13 : 9811904367
Total Pages : 244 pages
Book Rating : 4.8/5 (119 download)

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Book Synopsis III-Nitride LEDs by : Shengjun Zhou

Download or read book III-Nitride LEDs written by Shengjun Zhou and published by Springer Nature. This book was released on 2022-05-26 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights state-of-the-art in III-nitrides-based light-emitting diodes (LEDs). Motivated by the application prospects in lighting, high-resolution display, and health & medicine, the book systematically introduces the physical fundamentals, epitaxial growth, and device fabrications of III-nitride-based LEDs. Important topics including the structures of chips, device reliability and measurements and the advances in mini and micro LEDs are also discussed. The book is completed with a decade of research experience of the author’s team in the design and fabrication of III-nitrides-based LEDs, presenting the novel achievements in the stress control of the large mismatch heterostructures, defect formation and inhibition mechanism of the heteroepitaxial growth, LED epitaxial technologies, and the fabrication of high-efficient flip-chip LEDs. The book comprises of a valuable reference source for researchers and professionals engaged in the research and development of III-nitrides-based LEDs.