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Author: Shuailong Zhang Publisher: ISBN: Category : Languages : en Pages : 418
Book Description
III-nitride micro-pixellated light-emitting diodes (micro-LEDs) are a novel format of light source capable of generating micro-scale, spatially and temporally-controllable light patterns. These devices consist of arrays of LED pixels with diameters in the range of 1 μm to 100 μm and emit light across the ultraviolet-blue-green-red part of the spectrum. In addition, compared with conventional broad-area LED devices, micro-LEDs show improved device performance in many aspects, such as high output power densities and the capability to withstand high injection current densities. For these reasons, micro-LEDs allow the study of interesting LED properties in regimes not accessible to conventional broad-area LEDs and also a wide range of novel LED applications. The research work presented in this thesis focuses on the novel applications of micro-LEDs in visible light communications (VLC) and micro-displays. Due to a reduced current crowding effect and superior thermal management capabilities, micro-LEDs can be driven at very high current densities, resulting in high modulation bandwidths of the devices. For this reason, optical data transmission was demonstrated from individual micro-LED pixels at bit rates of up to 1 Gbit/s using a high-speed probe under a binary amplitude modulation scheme. To make a more practical VLC system, micro-LED devices were integrated with specifically-designed complementary metaloxide-semiconductor (CMOS) electronics, which allow individual micro-LED pixels to be conveniently controlled via a simple computer interface. Such CMOS-controlled micro-LED devices have been demonstrated for data transmission at bit rates of up to 512 Mbit/s by modulating a single CMOS/micro-LED pixel and 1.5 Gbit/s by modulating four CMOS/micro-LED pixels simultaneously. Apart from the application in VLC, CMOS-controlled micro-LED devices can also be used to implement micro-display systems. A colour-tunable micro-display system capable of delivering high-resolution microscale dynamic images and tuning its colour from red to green has been demonstrated based on new LED epitaxial LED structures, micro-LED fabrication, and the CMOS technology. Other work reported in this thesis includes using micro-LEDs for data transmission in plastic optical fibre and investigating the modulation characteristics of colour-converters such as colloidal quantum dots and light-emitting polymer. A detailed study on size-dependent capacitance in III-nitride micro-LEDs, especially the negative capacitance (NC) effect, has also been reported in this thesis. This capacitance research sheds light on the mechanisms underlying the NC effect and is potentially useful for improving the LED performance for VLC and other applications.
Author: Shuailong Zhang Publisher: ISBN: Category : Languages : en Pages : 418
Book Description
III-nitride micro-pixellated light-emitting diodes (micro-LEDs) are a novel format of light source capable of generating micro-scale, spatially and temporally-controllable light patterns. These devices consist of arrays of LED pixels with diameters in the range of 1 μm to 100 μm and emit light across the ultraviolet-blue-green-red part of the spectrum. In addition, compared with conventional broad-area LED devices, micro-LEDs show improved device performance in many aspects, such as high output power densities and the capability to withstand high injection current densities. For these reasons, micro-LEDs allow the study of interesting LED properties in regimes not accessible to conventional broad-area LEDs and also a wide range of novel LED applications. The research work presented in this thesis focuses on the novel applications of micro-LEDs in visible light communications (VLC) and micro-displays. Due to a reduced current crowding effect and superior thermal management capabilities, micro-LEDs can be driven at very high current densities, resulting in high modulation bandwidths of the devices. For this reason, optical data transmission was demonstrated from individual micro-LED pixels at bit rates of up to 1 Gbit/s using a high-speed probe under a binary amplitude modulation scheme. To make a more practical VLC system, micro-LED devices were integrated with specifically-designed complementary metaloxide-semiconductor (CMOS) electronics, which allow individual micro-LED pixels to be conveniently controlled via a simple computer interface. Such CMOS-controlled micro-LED devices have been demonstrated for data transmission at bit rates of up to 512 Mbit/s by modulating a single CMOS/micro-LED pixel and 1.5 Gbit/s by modulating four CMOS/micro-LED pixels simultaneously. Apart from the application in VLC, CMOS-controlled micro-LED devices can also be used to implement micro-display systems. A colour-tunable micro-display system capable of delivering high-resolution microscale dynamic images and tuning its colour from red to green has been demonstrated based on new LED epitaxial LED structures, micro-LED fabrication, and the CMOS technology. Other work reported in this thesis includes using micro-LEDs for data transmission in plastic optical fibre and investigating the modulation characteristics of colour-converters such as colloidal quantum dots and light-emitting polymer. A detailed study on size-dependent capacitance in III-nitride micro-LEDs, especially the negative capacitance (NC) effect, has also been reported in this thesis. This capacitance research sheds light on the mechanisms underlying the NC effect and is potentially useful for improving the LED performance for VLC and other applications.
Author: Jinmin Li Publisher: Springer Nature ISBN: 9811579490 Category : Technology & Engineering Languages : en Pages : 295
Book Description
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.
Author: Publisher: Academic Press ISBN: 0128230630 Category : Science Languages : en Pages : 412
Book Description
MicroLEDs', Volume 106 is currently recognized as the ultimate display technology and one of the fastest-growing technologies in the world as technology giants utilize it on a wide-ranging set of products. This volume combines contributions from MicroLED pioneers and world’s leading experts in the field who focus on the MicroLED development, current cutting-edge technologies of pursuing for realizing MicroLED large flat panel displays and televisions, virtual reality and 3D displays, light source for LI-FI data communications, neural interface and optogenetics, and future MicroLED technology trends. Contains contributions from original MicroLED inventors and pioneers Provides the most comprehensive and updated status of MicroLED technological advancements and applications Updates on future MicroLED technology trends
Author: Shengjun Zhou Publisher: Springer Nature ISBN: 9811904367 Category : Science Languages : en Pages : 244
Book Description
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.
Author: Pengfei Tian Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
This thesis presents a systematic study of the fabrication, efficiency and applications of micro-pixelated III-nitride light emitting diodes (micro-LEDs). Efficiency droop studies of micro-LEDs and the development of new-types of micro-LEDs have been investigated. The size dependence and temperature dependence of micro-LED efficiency droop have been analysed, providing a deep understanding of efficiency droop issue for general lighting and also demonstrating the advantages of micro-LEDs to alleviate such efficiency droop. Micro-LEDs on flexible substrates have been fabricated, which combine the flexibility of soft substrates and the high efficiency of inorganic LEDs for potential applications in flexible displays, biomedicine, etc. In addition, micro-LEDs on Si substrates were also fabricated to reduce the micro-LED device fabrication cost. The size-dependent efficiency droop study demonstrates that the smaller micro-LEDs have more uniform current spreading, which causes their higher efficiency and higher thermal saturation current density. In addition, the temperature-dependent efficiency droop study shows that both the radiative and Auger recombination coefficients decrease with increasing temperature, and the temperature dependence of the radiative and Auger recombination coefficients is weaker at a higher current density. So micro-LEDs possess stabler temperature dependent efficiency when operating at a high current density. Flexible micro-LEDs have been fabricated using metal bonding and laser lift off techniques with only one transfer step. Also, the micro-LED arrays on Si substrates were developed for the first time, which have lower fabrication cost compared with micro-LEDs on sapphire substrates. The applications in micro-display and visible light communication have been demonstrated for both the devices above. This work suggests that employing micro-LED techniques is a way to improve LED efficiency for general lighting. With development of flexible micro-LEDs and reduced fabrication cost of micro-LEDs on Si substrates, the future applications of micro-LEDs are expected to be greatly expanded.
Author: Jian-Jang Huang Publisher: Woodhead Publishing ISBN: 0081019432 Category : Technology & Engineering Languages : en Pages : 826
Book Description
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
Author: Tae-Yeon Seong Publisher: Springer ISBN: 9811037558 Category : Science Languages : en Pages : 498
Book Description
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.
Author: Enyuan Xie Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The research work presented in this thesis focuses on the mechanisms and development of novel III-nitride microstructured light emitting diodes (LEDs). In particular, we focus on micro-sized LEDs (`μ-LEDs') and LEDs containing micro- scale emission images i.e. `microstructured-image LEDs'. III-nitride μ-LEDs, which are devices with dimensions less than 100 μm, show improved device performance and novel potential applications compared with broad- area LEDs. The internal electric field in III-nitride materials, which is mainly caused by the strain due to lattice mismatch with the substrate, is a serious issue for III-nitride LEDs. As the strain can be relaxed in micro-scale structures, the performance of μ-LEDs can be improved. In this work, we have investigated the strain relaxation process in III-nitride micro-pillars as a function of pillar diameter by high-spatial-resolution cathodoluminescence. The results of this study give a guideline for further design of μ-LEDs with high efficiency. The internal electric field can also be screened by injection of carriers, leading to a blue-shift of the emission wavelength for III-nitride LEDs. Due to the high operating current density that μ-LEDs can sustain, the magnitude of this blue-shift is remarkably increased for μ-LEDs. Based on this characteristic, colour-tunable μ-LEDs have been demonstrated in this work, which offers a simple way to achieve multi-colour displays. In order to further improve the performance of μ-LEDs, we have also developed Pd-based contacts to p-type GaN and investigated the current-density dependent specific contact resistivity. At high current densities, the μ-LEDs with optimized Pd-based contacts have better electrical performance compared with devices using oxidized Ni/Au contacts. The optimized Pd-based contact also leads to improved optical power for blue LEDs in flip-chip configurations. III-nitride microstructured-image LEDs are devices in which micro-scale emission patterns are created in single LEDs. These devices offer a simple approach to the display of high-resolution images. CHF3 plasma treatment is a novel technique used for the fabrication of these devices. This plasma treatment can locally modify the electrical properties of p-type GaN and define the emission image. An application of these devices for maskless image writing is demonstrated.
Author: Choudhury J. Praharaj Publisher: John Wiley & Sons ISBN: 111970863X Category : Technology & Engineering Languages : en Pages : 196
Book Description
Discover a comprehensive exploration of the foundations and frontiers of the optoelectronics technology of group-III nitrides and their ternary alloys In Group III-Nitride Semiconductor Optoelectronics, expert engineer Dr. Choudhury J. Praharaj delivers an insightful overview of the optoelectronic applications of group III-nitride semiconductors. The book covers all relevant aspects of optical emission and detection, including the challenges of optoelectronic integration and a detailed comparison with other material systems. The author discusses band structure and optical properties of III-nitride semiconductors, as well as the properties of their low-dimensional structures. He also describes different optoelectronic systems such as LEDs, lasers, photodetectors, and optoelectronic integrated circuits. Group III-Nitride Semiconductor Optoelectronics covers both the fundamentals of the field and the most cutting-edge discoveries. Detailed appendices contain Maxwell's equations in dielectric media and descriptions of time-dependent perturbation theory and light-matter interaction. Readers will also benefit from: A thorough introduction to the band structure and optical properties of group III-nitride semiconductors Comprehensive explorations of growth and doping of group III-nitride devices and heterostructures Practical discussions of the optical properties of low dimensional structures in group III-nitrides In-depth examinations of lasers and light-emitting diodes, other light-emitting devices, photodetectors, photovoltaics, and optoelectronic integrated circuits Concise treatments of the quantum optical properties of nitride semiconductor devices Perfect for researchers in electrical engineering, applied physics, and materials science, Group III-Nitride Semiconductor Optoelectronics is also a must-read resource for graduate students and industry practitioners in those fields seeking a state-of-the-art reference on the optoelectronics technology of group III-nitrides.
Author: Matthew Hartensveld Publisher: ISBN: Category : Field-effect transistors Languages : en Pages : 244
Book Description
"Gallium Nitride (GaN) light emitting diodes (LEDs) are viewed as the next generation of display technology as a replacement for both liquid crystal displays (LCDs) and organic light emitting diode (OLED) displays. GaN based LEDs offer immense improvements in terms of efficiency, reliability, and resolution as compared to these conventional display technologies. New device opportunities are presented with the advent of LED displays, however there are a number of key challenges that also need to be addressed. Displays rely upon transistors in order to individually control the brightness of each color in a pixel. LED displays are no different, though there are no straightforward ways to pair transistors with LEDs. Furthermore, LEDs still leave room for improvement, suffering from poor p-type activation, single color emission, and inflexibility. Though with the promise of GaN LEDs, new integration approaches are realized here to overcome these limitations.To address the challenge of transistors and LEDs, an innovative integration between LEDs and field effect transistors (FETs) has been demonstrated. The integrated LED-FET devices lead to dramatic increases in resolution, substantial decreases in processing steps, and considerable area savings. Device and simulation results are presented, with further scaling optimizations outlined. The idea of full color integration has been a challenge for LEDs, where often multiple material systems are combined in order to realize these displays. Multiple materials translate to higher costs and lower resolution, as separate fabrication is performed to create these LEDs and then transfer the LEDs together. Monolithic approaches have been pursued, though necessitate the use of rare-earth materials. Instead, the structure of the LED is exploited in order to create the full range of LED colors from red to blue in a simple, efficient, monolithic format to demonstrate multi-color [micro]-LEDs. Several novel devices and integration schemes are also presented that expand upon the existing device applications. Work developing a novel nanowire lift-off mechanism is presented which allows for both substrate reuse, as well as flexible devices. A capacitor-LED integration mechanism is demonstrated to enhance hole activation and utilization. AC operating LEDs are demonstrated through tunneling. Integration of high-power devices are additionally investigated for driving higher power LEDs. Together these breakthroughs provide a pathway for LED displays and beyond."--Abstract.
Author: Shuailong Zhang
Author: Shuailong Zhang
Author: Jinmin Li
Author: 
Author: Shengjun Zhou
Author: Pengfei Tian
Author: Jian-Jang Huang
Author: Tae-Yeon Seong
Author: Enyuan Xie
Author: Choudhury J. Praharaj
Author: Matthew Hartensveld