Download or read book Studies of Gallium Nitride Based Schottky Barrier Diodes and Light Emitting Diodes written by Chen Mo and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The surface roughness and nitrogen deficiencies caused by inductively coupling plasma etching have been major problems in manufacturing GaN based electronic and photonic devices. The surface of Gallium Nitride needs recovery treatment after plasma etching. In my research of Schottky Barrier Diodes, the above-mentioned problems were addressed by developing a novel KOH-etching approach to remove the surface residues. Based on the analysis of current density to voltage curve, KOH solution treatment helps to remove the etch-damaged layer and flattening the surface morphology. The sample with KOH solution has lower surface density, shorter defect region thickness and higher barrier, and all of which will reduce the leakage current with several orders of magnitude. In my research of GaN based Micro LEDs, the sidewall of the mesa is protected by a layer of SiO2 with atomic layer deposition (ALD) after ICP etching. We analyzed that the passivation layer helps to deactivate surface traps and reduce leakage current in forward bias. According to the simulation results and the light-current-voltage measurements, the sidewall passivation layer grown by atomic layer deposition reduces the Schottky Reed Hall non-radiative recombination rate, thereby increasing the external quantum efficiency. From the experimental results, the improvement of the pixel's quantum efficiency at 150K is significantly higher than that at 300K. Shockley-Read-Hall nonradiative recombination rate decreases rapidly at low temperature due to longer carrier lifetime and increased difficulty of electron and hole recombination in traps. From the modeling results, the circular shaped pixels have better performance than square shaped pixels due to the following reasons: (1) the sharp corners have more surface roughness and defects during fabrication (2) the circular shaped pixel has better current spreading.
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
Download or read book Electrical and Optical Studies on Modeling and Fabrication of Gallium Nitride GaN Based Optoelectronic Devices written by Asim Mohammed A. Noor Elahi and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work in this dissertation is divided into two parts. The first part is related to the study of integration optoelectronic devices, such as Schottky Barrier Diodes (SBDs) and Metal Semiconductor Field Effect Transistors (MESFETs), along with Light Emitting Diodes (LEDs) on the same electronic chip. The second part of this dissertation is concerned with the electrical and optical modeling of gap-free microdisplay devices of based on gallium nitride, GaN, the optical modeling of nanophosphor-coupled porous layers for color conversion in III-Nitride microLED arrays, and also with some experimental studies on the photochemical and thermal stabilities of QDs materials that are integrated in the structure of GaN microLED devices. It is concluded from the first part of this work that the buffer layer located at the interface of unintentionally doped GaN layer and sapphire substrate has a strong effect on the forward current properties of lateral-type GaN Schottky diodes and plannar GaN metal-semiconductor-field-effect-transistors (MESFETs) grown on sapphire substrates (chapter 2). Experimental and simulation results have revealed that the interfacial region is acting as a channel in which the current passes in between the device metallic contacts because of the high conductivity that arises from a significant number of threading dislocations that are decorated by impurities due to the large lattice mismatches between GaN and sapphire. Owing to the presence of the interfacial regions, the lateral Schottky diodes exhibit high current densities but without change in their on-state-voltage, whereas the planar MESFETs could hardly reach cut-off or show saturation behavior. As a result, GaN-based vertical metal-semiconductor field-effect transistors(MESFETs) on commercial light-emitting-diode (LED) epi-wafers was fabricated and designed to overcome the latter problem (chapter 3). Also, the devices studied were simulated using charge transport model for better understanding of the current-voltage relationship. It was found that shrinking the size of the drain pillar helps reaching cut-off at much lower gate bias, even at high carrier concentration of unintentionally doped GaN and also with considerable leakage current caused by the Schottky barrier lowering. From the second part of the dissertation, it is disclosed that the isolation barrier region offers a better performance of a microLED microdisplay by minimizing the light cross-talk between the microLED pixels (chapter 4). It was found from the optical modeling results that the light cross-talk between the microLED pixels including the illuminating one in the isolation barrier planar structure is decreased significantly compared to the light cross-talk from all the pixels including the illuminating one in the non-planar air gap conventional structure of a microdisplay. The electrical simulation results reveal that the cross-talk current depends on the implanted ions energy, implanted ions dose and the width of the isolation barrier. The cross-talk current between the devices is decreased and the number of the affected pixels in the same row of a microdisplay is also reduced by the increase of the impurity concentration in the isolation barriers since the implanted ions are introducing deep level traps which results in current isolation between devices. Since the current microLED arrays are monochromatic emitting devices, nanophosphor-coupled nanoporous layers in III-nitride microLED arrays has been used to create colorful microLED arrays. The structure of those devices has been numerically analyzed along with its impacts on the application of microLED matrices in colorful display panels (chapter 5). It is concluded from the computational analysis carried out in this project that there remain some key challenges that need to be addressed in order to use such a structure in developing full-color miroLED display panels that simultaneously preserve the high-resolution and efficiency performances of microLED display devices. The extraction efficiency of both excitation (blue) and down-conversion (red) light from a nanophosphor-coupled LED devices have been demonstrated to drop drastically beyond specific thresholds when the porosity and thickness of the porous down-conversion layer increases. Additionally, it is found from the simulation that the cross-talk of down-converted light between adjacent micro-LED pixels is substantially higher compared to the excitation light cross-talk due to the location of the phosphors in the pore cavities and the resultant strong scattering by the surrounding nanopores. Furthermore, the instability of QDs is still a serious concern for the implementation of those emissive materials in the microLED display panels. Therefore, in Chapter 6, experimental studies on the thermal and photochemical stabilities of multicolored microLED display panels are presented. This chapter studied the thermal and photochemical stabilities of a 15 micrometer-thick layer of mixed red, green, and blue quantum dots produced via spin-cast deposition over a blue microLED matrix. This study also looked at the optical properties of QDs-based multicolored microLEDs. The results in this work provided us with a basic understanding of the ultimate limit of QD performance in microLED devices. The stability assessment results support and inspire the use of red, green, and blue QDs layers in blue microLED matrices to produce full-color microLED devices. Such research will aid in the design and production of high-efficiency, high-performance micro-LED display panels. Finally, Chapter 7 presents suggestions for the proposed future research in the field related to the scope of investigation reported in this thesis.
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.
Download or read book Gallium Nitride based Electronic and Optoelectronic Devices written by Li Wang and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For the past decade, Gallium nitride (GaN) material system has earned a significant place in modern power electronic and optoelectronic devices due to its outstanding electric and optical properties. GaN-based device technologies have improved substantially, and are still investigated intensely for advanced performance. The GaN-based devices studied in this dissertation involve Schottky barrier diodes (SBDs) and high electron mobility transistors (HEMTs) on the electronic side and light emitting diodes (LEDs) on the optoelectronic side.In the SBDs part, GaN SBDs with high voltage blocking capability and low on-state voltage on inductively coupled plasma (ICP) etched commercial LED epi-wafers are studied. Their applications in alternating current (AC) LEDs are demonstrated. It is revealed that the potassium hydroxide (KOH) pretreatment with optimized concentration could eliminate the leakage current due to the reduction of the ICP induced surface defects. Moreover, the numerical values of the surface defect density are extracted by analyzing the leakage current mechanism. In the HEMTs part, the transfer saturation feature of GaN-based HEMTs is investigated firstly. It is observed that the drain current in HEMTs with short gate length becomes saturation as gate bias approaches zero. The theoretical analysis based on a simple series resistance model reveals this saturation feature results from the fact that the total source-drain resistance is independent on gate bias in a short gate length HMET. This conclusion is further verified by device simulation study. Secondly, novel GaN double-gate (DG) HEMTs featuring enhanced back gate-control of the two dimensional electron gas (2DEG) in AlGaN/GaN heterostructures is designed and modeled. The results indicate that the DG GaN-HEMTs can provide a higher maixmum transconductance gain and better immunity of the short channel effects than traditional single-gate HEMTs. At last, the temperature-dependent electrical characteristics of GaN-based HEMTs from room temperature down to 50K are studied. It is observed that the drain saturation current and transconductance increase with the decrease of the temperature. In the LEDs part, quantum dots (QDs) coupled non-resonant microcavity light emitting diodes (LEDs) with micro-holes is designed and demonstrated to enhance non-radiative energy transfer between InGaN/GaN quantum wells (QWs) and QDs for the first time by tailoring the radiative relaxation lifetime of excitations in QWs. The blue emission from the InGaN/GaN QWs is detuned from the resonant modes of the microcavity to extend the radiative recombination lifetime in QWs. The direct contact of QDs and the QWs active layer is achieved by depositing QDs into the micro-holes on the LEDs. This non-resonant microcavity structure leads to a 3.2 times enhancement of the effective quantum efficiency of QDs in microcavity LEDs than the LEDs without microcavity structure.
Download or read book Electrical Studies on Schottky Barrier Diodes SBDs on Gallium Nitride GaN written by Asim Noor Elahi and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the thesis describes experiments made on both GaN Schottky barrier diodes (SBDs) and commercially available SiC Schottky barrier diodes (SBDs). The electrical characterizations on both devices were investigated. Current -- Voltage technique was used for finding the barrier height and the ideality factor. Capacitance -- Voltage characterization technique is also used to obtain the value of the carrier concentration of both GaN and SiC SBDs and also. Thermally Stimulated Capacitance (TSCAP) graph was used on GaN SBDs device to detect the traps and their concentrations. Charge based -- Deep Level Transients Spectroscopy (Q-DLTS) mechanism was applied to both GaN and SiC SBDs for the investigation of the deep charge trapping levels in both devices. The measurements employed included Schottky output characteristics at room temperature and at different temperature values.It is concluded from the experiments that the barrier height for both devices is increasing with the increase of the temperature whereas the ideality factor is decreasing with the increase of the temperature. The values of the barrier height and the ideality factor of GaN Schottky diode are 0.35 eV and 1.2 at 120K and 0.93 eV and 0.47 at 430K, respectively. The value of the barrier height and the ideality factor of SiC Schottky diode are 0.36 eV and 1.5 at 120K and 1.14 eV and 0.4 at 430K, respectively. Three different regions were selected to calculate the carrier concentration of the SiC and GaN SBDs from the C-V characteristics at room temperature. The carrier concentration of the SiC remains constant through the three regions while the carrier concentration of GaN device increases as the reverse bias increases. Two traps have been found by applying the TSCAP technique to GaN Schottky barrier diodes. The first trap was located at 200 K with a concentration of 2.28x1018 cm-3 and the second trap was located at 300 K with a concentration of 3.56x1017 cm-3. For Q-DLTS measurements, unfortunately no traps have been detected for both the GaN and SiC SBDs and therefore no DLTS signals can be shown from the this experiment.
Download or read book Gallium Nitride GaN written by Farid Medjdoub and published by CRC Press. This book was released on 2017-12-19 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: Addresses a Growing Need for High-Power and High-Frequency Transistors Gallium Nitride (GaN): Physics, Devices, and Technology offers a balanced perspective on the state of the art in gallium nitride technology. A semiconductor commonly used in bright light-emitting diodes, GaN can serve as a great alternative to existing devices used in microelectronics. It has a wide band gap and high electron mobility that gives it special properties for applications in optoelectronic, high-power, and high-frequency devices, and because of its high off-state breakdown strength combined with excellent on-state channel conductivity, GaN is an ideal candidate for switching power transistors. Explores Recent Progress in High-Frequency GaN Technology Written by a panel of academic and industry experts from around the globe, this book reviews the advantages of GaN-based material systems suitable for high-frequency, high-power applications. It provides an overview of the semiconductor environment, outlines the fundamental device physics of GaN, and describes GaN materials and device structures that are needed for the next stage of microelectronics and optoelectronics. The book details the development of radio frequency (RF) semiconductor devices and circuits, considers the current challenges that the industry now faces, and examines future trends. In addition, the authors: Propose a design in which multiple LED stacks can be connected in a series using interband tunnel junction (TJ) interconnects Examine GaN technology while in its early stages of high-volume deployment in commercial and military products Consider the potential use of both sunlight and hydrogen as promising and prominent energy sources for this technology Introduce two unique methods, PEC oxidation and vapor cooling condensation methods, for the deposition of high-quality oxide layers A single-source reference for students and professionals, Gallium Nitride (GaN): Physics, Devices, and Technology provides an overall assessment of the semiconductor environment, discusses the potential use of GaN-based technology for RF semiconductor devices, and highlights the current and emerging applications of GaN.
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.
Download or read book Synthesis of Compound Semiconducting Materials and Device Applications Gallium Nitride Light Emitting Diodes written by Stanford University. Center for Materials Research and published by . This book was released on 1973 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and characterization of hetero-epitaxial gallium nitride (GaN) films were undertaken with particular reference to the phenomenon of light emission. Gallium nitride was grown by the chemical vapor deposition technique using sapphire substrates. Techniques for characterization included optical, scanning electron, and transmission electron microscopy and measurements of various electrical and optical properties of the films. The thin films of GaN were doped during growth with zinc and magnesium to form n-i junctions. Such material provided the basis for the fabrication of m-i-n light-emitting diodes, which emitted light in the high-energy violet region of the visible spectrum with Mg doping and green light with Zn doping. (Modified author abstract).
Download or read book Design Fabrication and Characterization of Gallium Nitride based Blue Light emitting Diodes written by Yuxin Li and published by . This book was released on 1998 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Investigations of High Efficiency Vertical Structured GaN based Schottky Barrier Diodes and Light Emitting Diodes written by 陳聰敏 and published by . This book was released on 2007 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Novel Schottky Contacts to N Type Gallium Nitride written by Varra Rajagopal Reddy and published by LAP Lambert Academic Publishing. This book was released on 2011-03 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Group III-V wide band gap semiconductor particularly GaN received a great deal of attention in the past decade due to its potential for the realization of electronic and optoelectronic devices. Its wide band gap, high break down field, and high electron saturation velocity also make it an attractive candidate for the development of electronic devices operating at high temperature, high power and high frequency devices such as light emitting diodes, laser diodes, metal-semiconductor field effect transistors and high electron mobility transistors. Especially, the performance and reliability of these devices have been improved with high quality ohmic and Schottky rectifiers. However, larger leakage current through Schottky rectifiers adversely affects the operation, power consumption, noise and reliability of devices. Hence, Schottky rectifier for GaN with ultra low leakage current is one of the challenges to their use in optoelectronic and electronic devices. Therefore, it is necessary to obtain a high Schottky barrier height at the metal/semiconductor (MS) interface to reduce the leakage current and to improve break down voltage in Schottky diodes.
Download or read book Non ideal Properties of Gallium Nitride Based Light emitting Diodes written by Qifeng Shan and published by . This book was released on 2012 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simulation Optimisation and Manufacture of Gallium Nitride Based Blue Light Emitting Diodes on Silicon Substrates written by Kat Vinden and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Resolution Electron Beam Testing of Gallium Nitride Based Light Emitting Diodes written by Curtis Lorenz Progl and published by . This book was released on 2008 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: GaN, MQW LEDs, STEM, EBIC, CL, V-defects.
Download or read book Disruptive Wide Bandgap Semiconductors Related Technologies and Their Applications written by Yogesh Kumar Sharma and published by BoD – Books on Demand. This book was released on 2018-09-12 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: SiC and GaN devices have been around for some time. The first dedicated international conference on SiC and related devices, "ICSCRM," was held in Washington, DC, in 1987. But only recently, the commercialization of SiC and GaN devices has happened. Due to its material properties, Si as a semiconductor has limitations in high-temperature, high-voltage, and high-frequency regimes. With the help of SiC and GaN devices, it is possible to realize more efficient power systems. Devices manufactured from SiC and GaN have already been impacting different areas with their ability to outperform Si devices. Some of the examples are the telecommunications, automotive/locomotive, power, and renewable energy industries. To achieve the carbon emission targets set by different countries, it is inevitable to use these new technologies. This book attempts to cover all the important facets related to wide bandgap semiconductor technology, including new challenges posed by it. This book is intended for graduate students, researchers, engineers, and technology experts who have been working in the exciting fields of SiC and GaN power devices.
Download or read book White Light emitting Diodes Based on Nonpolar and Semipolar Gallium Nitride Orientations written by Natalie Fellows DeMille and published by . This book was released on 2009 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this research deals with exploring white illumination on nonpolar and semipolar planes of GaN. Light extraction techniques will be described that allowed for high output powers and efficiencies on the c-plane as well as the (1100), (10 11), and (1122) planes of GaN. With higher performing devices, white pcLEDs were fabricated on c-plane, m-plane, and the (1011) semipolar plane.
