Download or read book Investigation of Electrically Active Defects in GaN AlGaN and AlGaN GaN High Electron Mobility Transistors written by Aaron R. Arehart and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To further refine the capabilities to quantitativelymeasure defect energies and concentrations in the access regions of HEMTs, an atomic forcemicroscope is adapted to perform nanometer-scale defect characterization. Using scanning Kelvin probe microscopy, evidence of the spatial and time-dependent measurement capabilities is demonstrated. Initial HEMT results are presented and suggest the total trap concentration of ~1012 cm−2 consistent with previous results.

Download or read book Investigation of Electrically active Defects in AIGaN GaN High Electron Mobility Transistors by Spatially resolved Spectroscopic Scanned Probe Techniques written by Drew Cardwell and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The nm-scale trap spectroscopy techniques were used to spatially resolve particular traps in AlGaN/GaN HEMTs grown by metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). Typically, deeper traps were observed in the AlGaN barrier layer, within several hundred nanometers of the gate edge in the drain access region, in both MOCVD and MBE-grown HEMTs. Measurements on MOCVD-grown HEMTs with Fe-doped GaN buffer layers indicated that an Ec - 0.57 eV trap is located in the GaN buffer layer and is correlated with the presence of Fe in the GaN buffer.

Download or read book Impact of Electrically and Thermally Induced Physical Defects on the Reliability of AlGaN GaN High Electron Mobility Transistors written by Monta Raymond Holzworth (Jr) and published by . This book was released on 2013 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: AlGaN/GaN high electron mobility transistors are unique for their combination of high temperature, high power, and high frequency applications. Compared to Si, Ge, and compound semiconductors such as GaAS and InP, AlGaN/GaN transistors outclass the current technology due to their superior combination of high breakdown voltage and high frequency performance. These characteristics arise from structural and electrical properties inherent to the AlGaN/GaN heterojunction which have enabled AlGaN/GaN transistors usage in important military and civilian applications such as microwave and millimeter technology, RADAR systems, and as high current and voltage switches in utility grid systems. As the technology continues to improve due to increased materials quality and device advancements, future applications will require AlGaN/GaN transistor usage under even higher voltages and temperatures. Therefore, the effects of these stresses need to be investigated in order improve device performance and reliability.

Download or read book Dynamic Performance Simulation of AlGaN GaN High Electron Mobility Transistors written by Shrijit Mukherjee and published by . This book was released on 2019-05-31 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: GaN based devices have reached a point in terms of processing maturity where the favorable wide-band gap related properties can be implemented in several commercial and military applications. However, long term reliability continues to affect large scale integration of such devices, specifically the potential of AlGaN/GaN High Electron Mobility Transistors (HEMTs), due to the indefinite nature of defects in the structure and mechanisms of performance degradation relevant to such defects. Recent efforts have begun to concentrate more on the bulk properties of the GaN buffer on which the heterostructure is grown, and how defects distributed in the buffer can affect the performance under various operating schemes. This dissertation discusses numerical simulator based investigation of the numerous possibilities by which such point defects can affect electrical behavior. For HEMTs designed for satellite communication systems, proton irradiation results indicate changes in the device parasitics resulting in degradation of RF parameters. Assumption of such radiation damage introducing fast traps indicate severe degradation far exceeding experimental observation. For power switching applications, the necessity of accurately capturing as-grown defects was realized when modeling current relaxation during bias switching. Ability to introduce multiple trap levels in the material bulk aided in achieving simulation results replicating experimental results more accurately than published previously. Impact of factors associated with such traps, either associated with discrete energy levels or band-like distribution in energy, on the nature of current relaxation characterized by its derivative has been presented. Dissertation Discovery Company and University of Florida are dedicated to making scholarly works more discoverable and accessible throughout the world. This dissertation, "Dynamic Performance Simulation of AlGaN/GaN High Electron Mobility Transistors" by Shrijit Mukherjee, was obtained from University of Florida and is being sold with permission from the author. A digital copy of this work may also be found in the university's institutional repository, IR@UF. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation.

Download or read book Power GaN Devices written by Matteo Meneghini and published by Springer. This book was released on 2016-09-08 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the first comprehensive overview of the properties and fabrication methods of GaN-based power transistors, with contributions from the most active research groups in the field. It describes how gallium nitride has emerged as an excellent material for the fabrication of power transistors; thanks to the high energy gap, high breakdown field, and saturation velocity of GaN, these devices can reach breakdown voltages beyond the kV range, and very high switching frequencies, thus being suitable for application in power conversion systems. Based on GaN, switching-mode power converters with efficiency in excess of 99 % have been already demonstrated, thus clearing the way for massive adoption of GaN transistors in the power conversion market. This is expected to have important advantages at both the environmental and economic level, since power conversion losses account for 10 % of global electricity consumption. The first part of the book describes the properties and advantages of gallium nitride compared to conventional semiconductor materials. The second part of the book describes the techniques used for device fabrication, and the methods for GaN-on-Silicon mass production. Specific attention is paid to the three most advanced device structures: lateral transistors, vertical power devices, and nanowire-based HEMTs. Other relevant topics covered by the book are the strategies for normally-off operation, and the problems related to device reliability. The last chapter reviews the switching characteristics of GaN HEMTs based on a systems level approach. This book is a unique reference for people working in the materials, device and power electronics fields; it provides interdisciplinary information on material growth, device fabrication, reliability issues and circuit-level switching investigation.

Download or read book The Role of Defects on Schottky and Ohmic Contact Characteristics for GaN and AlGaN GaN High electron Mobility Transistors written by Dennis Eugene Walker and published by . This book was released on 2006 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The AlGaN/GaN material system is ideally suited for UV detectors, light sources, and high performance, high power transistors. Through an understanding of the physics and device properties associated with defects, engineered solutions can allow the utilization of the full potential of AlGaN/GaN device properties. Auger Electron Spectroscopy (AES) and secondary electron threshold (SET) techniques allow the characterization of band bending and work function at semiconductor surfaces. Using these techniques with ultra-high vacuum (UHV) sample cleaving and metal deposition, Schottky barrier formation to non-polar GaN was investigated revealing cases of both ideal band-bending and Fermi level pinning. Cathodoluminescence spectroscopy (CL) allows the investigation of luminescent defect levels with depth-resolving capability by controlling the incident beam voltage and associated electron beam penetration into the sample. High electron mobility transistors (HEMTs) exhibiting current collapse were investigated using CL and CL mapping and specific defects were found in the GaN channel and buffer regions that may help explain the current collapse phenomena. Coupling a novel gate mask into a typical HEMT fabrication sequence and utilizing three, independent UHV sample cleaning techniques including thermal desorption of contaminants, Ga-reflux, and N2 ion sputtering, and metallization of the gates on AlGaN/GaN HEMTs, correlations in defect levels, surface cleaning technique, and finished device performance were found. In analyzing the CL data for this sample, however, a specific feature located just below the GaN near band edge was observed to accumulate near the Ohmic contacts prompting a further investigation of both the effects of the RIE etch used in producing the UHV-compatible mask as well as four different Ohmic contact structures on both defect levels determined by CL and on final device performance. Finally, a bulk GaN sample was processed with Ohmic contacts to determine the correlation of the AlGaN device layer in the formation of this defect level associated with the Ohmic contacts and the role of the mesa RIE etch on the same defect. Through these investigations, progress in the underlying physics of Schottky barrier formation on GaN and the important role of defects on device performance using AES, SET, and CL have been demonstrated.

Download or read book Analysis and Optimization of AlGaN GaN High Electron Mobility Transistors for Microwave Applications written by Michael Hosch and published by Cuvillier Verlag. This book was released on 2011-08-08 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis deals with the analysis and optimization of some of the most prominent non-ideal effects in AlGaN/GaN high electron mobility transistors used in microwave applications as well as the optimization of the RF gain. The effect of current collapse, the root cause of leakage currents as well as field-dependent self-heating effects have been investigated by eletrical characterization using well established techniques and have been analyzed using 2-dimensional physical device simulations. It will be shown that the origin of all effects is strongly related to the device surface and some are even competing effects making device optimization a challenge. However, a detailed localization of the regions affecting device performance will be given leading to a better understanding for fabrication process optimization. Finally, I simulation study is conducted giving suggestions for RF gain improvement based on very simple device layout variations.

Download or read book Electrical Noise and Charge Transport Studies of AlGaN GaN High Electron Mobility Transistors written by Weikai Xu and published by . This book was released on 2014 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: AlGaN/GaN HEMTs have shown great performance in high frequency and high power applications. However, since the fabrication process of GaN devices is developed in recent years, it is not as mature as the silicon technology. Device reliability is one of the major issues that limit AlGaN/GaN HEMTs reaching their potential. In this work, unstressed and stressed AlGaN/GaN HEMTs are studied through I-V characteristics and low frequency noise measurements. Both the channel and the gate stack were examined to reveal the origins for device failure. Through noise measurement of channel, traps are found at AlGaN-GaN interface. A drain noise model is established to extract noise information of the gated part of the channel. For unstressed device the Hooge mobility fluctuation model dominates the noise mechanism, while the carrier number fluctuation model fits with the data of stressed devices. Hooge parameters and trap density are extracted for the channel part.

Download or read book Scanned Probe Spectroscopy of Traps in Cross sectioned AlGaN GaN Devices written by Darryl A. Gleason and published by . This book was released on 2019 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, scanning probe microscopy (SPM) methods are developed and extended to spatially resolve performance-hampering electrically-active defects, known as traps, present in AlGaN/GaN Schottky barrier diodes (SBDs) and high electron mobility transistors (HEMTs). Commercial devices used in these studies were cross-sectioned to expose electrically-active regions which are traditionally inaccessible to SPM techniques. Surface potential transients (SPTs) are collected over the cross-sectioned faces of devices using nanometer-scale scanning probe deep-level transient spectroscopy (SP-DLTS), a millisecond time-resolved derivative technique of scanning Kelvin probe microscopy (SKPM) that was implemented with a custom system designed to study SBDs and HEMTs in cross-section. Detected SPTs are indicative of carrier emission from bulk defect-related trap states. In conjunction with similar measurements of these trap states using macroscopic techniques, finite-element simulations provide strong, corroborating evidence that observable SPTs are produced by traps located in the bulk of these samples and are therefore not a result of surface states or surface-related phenomena. GaN-based materials offer advantages over many alternatives in high-frequency and high-voltage applications. Features including a wide bandgap and a large breakdown voltage often translate to improved efficiency, performance, and cost in many electronic systems. However, GaN-based material research is still maturing, and charge trapping may be a limiting factor in GaN electrical performance and therefore hinder its widespread application and adoption. Determining the signatures and spatial distributions of active traps in GaN devices is critical for understanding trap-related mechanisms of device failure as well as the growth or fabrication steps which may be responsible for introducing these defect states. Powerful techniques like deep-level transient spectroscopy (DLTS) exist for identifying specific traps in GaN, but the macroscopic variants of DLTS measure averaged trapping characteristics and are unable to precisely spatially locate the traps they measure. SP-DLTS is an extension of atomic force microscopy (AFM) and was developed approximately seven years prior to this writing. The technique uses SKPM to measure the local surface potential which is sensitive to modulations in the local trapped charge. Probing and analyzing the temperature-dependent SPTs using the same approach applied in the aforementioned conventional techniques reveals the signatures of traps which dominate the local SP-DLTS signal. Performing this measurement over a grid of locations (i.e. a map) provides nanometer-scale resolution of transients and therefore active trap modulation. However, device geometry is one primary limitation of plan-view or "top-down" SP-DLTS due to the sensitivity of the technique only to near-surface charge. Device features like electrodes can mask or electrically screen traps located in active device regions. Furthermore, in commercial devices like those studied here, metallic and passivation layers bury, screen, and/or mask traps in many device regions and completely prevent SP-DLTS probe access. Here, commercial AlGaN/GaN SBDs and HEMTs are cross-sectioned to expose their length and depth with sufficiently low surface damage to permit electrical access to traps beneath the cross-sectioned surface. SP-DLTS is used to detect and identify two distinct trap species with energies near EC − 0.6 eV and EC − 0.9 eV. Unlike macroscopic techniques, SP-DLTS affords trap studies under arbitrary bias conditions; the measurements indicate that trap occupancy modulation is observable during both the device on- and off-state, the latter of which is generally unreported in the literature since macroscopic techniques typically measure trap emission during the device on-state. In addition to qualitatively reproducing these experimental results, finite-element HEMT simulations reveal that current leakage mechanisms and the dopant-to-trap ratio in the GaN buffer likely strongly influence the signatures of detected traps by DLTS-based techniques. Collectively, this experimental and computational approach makes a significant advancement in the study and characterization of traps in AlGaN/GaN devices.

Download or read book Handbook for III V High Electron Mobility Transistor Technologies written by D. Nirmal and published by CRC Press. This book was released on 2019-05-14 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focusses on III-V high electron mobility transistors (HEMTs) including basic physics, material used, fabrications details, modeling, simulation, and other important aspects. It initiates by describing principle of operation, material systems and material technologies followed by description of the structure, I-V characteristics, modeling of DC and RF parameters of AlGaN/GaN HEMTs. The book also provides information about source/drain engineering, gate engineering and channel engineering techniques used to improve the DC-RF and breakdown performance of HEMTs. Finally, the book also highlights the importance of metal oxide semiconductor high electron mobility transistors (MOS-HEMT). Key Features Combines III-As/P/N HEMTs with reliability and current status in single volume Includes AC/DC modelling and (sub)millimeter wave devices with reliability analysis Covers all theoretical and experimental aspects of HEMTs Discusses AlGaN/GaN transistors Presents DC, RF and breakdown characteristics of HEMTs on various material systems using graphs and plots

Download or read book Fabrication of AlGaN GaN InN High Electron Mobility Transistors written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of various growth parameters such as temperature, V/III ratio and the growth rate on the properties of InN layers grown by MOCVD was investigated. The InN layers were deposited onto 2 micrometer thick GaN-on-c-plane sapphire films. In addition, the different precursor injection procedures were investigated. Since the growth of InN required very low deposition temperatures around 600 deg. C, for the deposition of InN/GaN heterostructures similar experiments were performed to optimize the growth of GaN at comparable growth temperatures. The fabrication of GaN/InN/GaN structures for device applications was complicated by intermixing and surface segregation of indium and defect formation in heterostructures related to the large lattice mismatch of 10% between GaN and InN.

Download or read book Reliability of W Band InAIN GaN High Electron Mobility Transistors written by Yufei Wu (Ph. D.) and published by . This book was released on 2017 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: AlGaN/GaN High Electron Mobility Transistors (HEMTs) have enjoyed tremendous market growth in RF power amplifiers over the past decades. In the quest for enhancing the operating frequency of GaN HEMTs, there has been a great effort to scale down the gate length. Maintaining acceptable short-channel effects requires shrinking the barrier thickness at the same time. However, a limitation exists since there is a minimum barrier thickness that is needed to obtain a sufficiently high two-dimensional electron gas density. One possible solution to this problem is the use of a new barrier material, i.e., InAlN. Due to its high spontaneous polarization, if InAlN is used as a barrier material in GaN HEMTs, a much smaller layer thickness is required compared with conventional HEMTs. This enables further barrier thickness scaling and therefore gate length scaling and a higher frequency response. However, as a relatively new structure, reliability studies of InAlN/GaN HEMTs are still lacking. Solid reliability is essential before the wide commercial deployment of this new technology. This thesis investigates the most relevant degradation mechanisms under important stress regimes, aiming at building a comprehensive understanding of InAIN/GaN HEMT reliability. Through investigating various voltage, current, and temperature stress levels, we have identified one recoverable degradation mechanism as well as three permanent degradation mechanisms. Under high drain voltage, hot-electron trapping results in temporary drain current decrease and drain resistance increase. In addition, under high drain voltage but relatively low drain current level, permanent negative threshold voltage shift and drain current increase have been observed. We attribute the phenomena to dehydrogenation of pre-existing defects in GaN channel by hot electrons. Under high positive gate bias, defect generation in the AIN interlayer due to high electric field across AIN has proven to be responsible for the observed gate leakage current increase. Also, under high-power stress conditions, positive threshold voltage shift and maximum drain current decrease have been consistently observed. We verified through both thermal stress experiments and Transmission Electron Microscopy (TEM) analysis that Schottky gate sinking is the cause. This work provides fundamental understanding of potential reliability concerns in InAlN/GaN HEMTs and is essential in accelerating the future commercialization of this promising technology.

Download or read book Modeling of AlGaN GaN High Electron Mobility Transistors written by D. Nirmal and published by Springer. This book was released on 2025-02-11 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume focuses on GaN HEMT, the most promising transistor technology for RF power applications such as 5G communications, space and defense. The contents include accurate small signal models required to predict the RF power performance of RF electronic circuits, large signal modeling of GaN HEMTs, accurate and compact physical models to assist the RF circuit designers to optimize GaN HEMT-based power amplifiers and integrated circuits, among others. The book also covers thermal resistance modeling of GaN HEMTs, charge-based compact models, and surface potential-based models to study the impact of gate leakage current on the RF power performance of GaN HEMTs. This book also deals with the analytical modeling of intrinsic charges and surface potential of GaN HEMTs, physical modeling of charge trapping, neural network-based GaN HEMT models, numerical-based GaN HEMT models, modeling of short channel effects in GaN HEMTs, modeling of parasitic capacitances and resistances, modelingof current collapse and kink effects in HGaN HEMTs, etc. This volume will be a useful to those in industry and academia.

Download or read book Handbook of GaN Semiconductor Materials and Devices written by Wengang (Wayne) Bi and published by CRC Press. This book was released on 2017-10-20 with total page 709 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses material growth, device fabrication, device application, and commercialization of energy-efficient white light-emitting diodes (LEDs), laser diodes, and power electronics devices. It begins with an overview on basics of semiconductor materials, physics, growth and characterization techniques, followed by detailed discussion of advantages, drawbacks, design issues, processing, applications, and key challenges for state of the art GaN-based devices. It includes state of the art material synthesis techniques with an overview on growth technologies for emerging bulk or free standing GaN and AlN substrates and their applications in electronics, detection, sensing, optoelectronics and photonics. Wengang (Wayne) Bi is Distinguished Chair Professor and Associate Dean in the College of Information and Electrical Engineering at Hebei University of Technology in Tianjin, China. Hao-chung (Henry) Kuo is Distinguished Professor and Associate Director of the Photonics Center at National Chiao-Tung University, Hsin-Tsu, Taiwan, China. Pei-Cheng Ku is an associate professor in the Department of Electrical Engineering & Computer Science at the University of Michigan, Ann Arbor, USA. Bo Shen is the Cheung Kong Professor at Peking University in China.

Download or read book Quantitative Defect Spectroscopy on Operating AlGaN GaN High Electron Mobility Transistors written by Andrew C Malonis and published by . This book was released on 2009 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Despite numerous advances in the growth, fabrication, and characterization of AlGaN/GaN HEMT devices, there remain a number of unknowns related to the impact of deep levels on HEMT performance. Of specific interest to ongoing development of HEMT technology is the development of techniques which can not only detect the specific energy levels of deep levels in operating devices, but can also relate the presence of these defects to changes in specific device parameters. By examining more established techniques and developing new on-device characterization methods, the impact of defects on AlGaN/GaN HEMTs was quantitatively studied.

Download or read book GaN Transistors for Efficient Power Conversion written by Alex Lidow and published by John Wiley & Sons. This book was released on 2019-08-12 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: An up-to-date, practical guide on upgrading from silicon to GaN, and how to use GaN transistors in power conversion systems design This updated, third edition of a popular book on GaN transistors for efficient power conversion has been substantially expanded to keep students and practicing power conversion engineers ahead of the learning curve in GaN technology advancements. Acknowledging that GaN transistors are not one-to-one replacements for the current MOSFET technology, this book serves as a practical guide for understanding basic GaN transistor construction, characteristics, and applications. Included are discussions on the fundamental physics of these power semiconductors, layout, and other circuit design considerations, as well as specific application examples demonstrating design techniques when employing GaN devices. GaN Transistors for Efficient Power Conversion, 3rd Edition brings key updates to the chapters of Driving GaN Transistors; Modeling, Simulation, and Measurement of GaN Transistors; DC-DC Power Conversion; Envelope Tracking; and Highly Resonant Wireless Energy Transfer. It also offers new chapters on Thermal Management, Multilevel Converters, and Lidar, and revises many others throughout. Written by leaders in the power semiconductor field and industry pioneers in GaN power transistor technology and applications Updated with 35% new material, including three new chapters on Thermal Management, Multilevel Converters, Wireless Power, and Lidar Features practical guidance on formulating specific circuit designs when constructing power conversion systems using GaN transistors A valuable resource for professional engineers, systems designers, and electrical engineering students who need to fully understand the state-of-the-art GaN Transistors for Efficient Power Conversion, 3rd Edition is an essential learning tool and reference guide that enables power conversion engineers to design energy-efficient, smaller, and more cost-effective products using GaN transistors.

Download or read book Investigation and Fabrication of AlGaN GaN Metal oxide semiconductor High electron Mobility Transistors with Surface Treatment and the I ZnO Gate Dielectric Layer written by 邱雅蘭 and published by . This book was released on 2011 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: