Simulation And Fabrication Of Gan Based Vertical And Lateral Normally Off Power Transistors
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Simulation And Fabrication Of Gan Based Vertical And Lateral Normally Off Power Transistors
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Author : Yuhao Zhang (S.M.)
language : en
Publisher:
Release Date : 2013
Simulation And Fabrication Of Gan Based Vertical And Lateral Normally Off Power Transistors written by Yuhao Zhang (S.M.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
This thesis is divided in two parts. First, self-consistent electro-thermal simulations have been performed for single finger and multi-finger GaN-based vertical and lateral power transistors and were validated with experimental DC characteristics. The models were used to study the thermal performance of GaN-based vertical metal oxide semiconductor field-effect transistors (MOSFETs) and the lateral high electron mobility transistors (HEMTs) designed for different breakdown voltage application and at different size scaling levels. The comparison between two structures revealed that the vertical MOSFETs have the potential to achieve an up to 50% higher thermal performance, especially for higher breakdown voltage and higher size scaling level designs. Second, normally-off lateral MOS-HEMTs were developed by the combination of fluorine plasma treatment and high-temperature gate oxide deposition. Record performances have been achieved for the fluorinated MOS-HEMTs with a threshold voltage >3.5 V, a low on-resistance ~ 2 m[Omega]·cm2, a small threshold voltage hysteresis ~0.15 V, high enhancement-mode channel mobility ~ 1000 cm2V-1s-1, a breakdown voltage ~ 780 V, no current collapse and a stability with 24 h continuous on-state operation at 250 oC. In addition, an analytical model for the threshold voltage of fluorinated MOS-HEMTs was established for the first time, to enable accurate design and engineering of the threshold voltage for MOS-HEMTs. This novel technology has been demonstrated as promising to fabricate high-performance normally-off MOS-HEMTs.
Design And Development Of Gan Based Vertical Transistors For Increased Power Density In Power Electronics Applications
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Author : Dong Ji
language : en
Publisher:
Release Date : 2017
Design And Development Of Gan Based Vertical Transistors For Increased Power Density In Power Electronics Applications written by Dong Ji and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Gallium nitride (GaN)-based devices have entered the power electronics market and shown excellent progress in the medium power conversion applications. For power conversions applications > 10 kW, devices with vertical geometry are preferred over lateral geometry, since the former allows more current for a given chip area, thus provides a more economical solution for high-voltage and high-current applications. Moreover, the vertical geometry is attractive for its dispersion-free performance without passivation, a phenomenon that causes high dynamic on-state resistance (R[subscript on]) in lateral geometry high electron mobility transistors (HEMTs). In this study, GaN-based vertical transistors, which include trench current aperture vertical electron transistors (CAVETs) and in-situ oxide, GaN interlayer based trench field-effect transistors (OGFETs), have been studied both theoretically and experimentally. In order to model the devices for DC and switching performances, a device/circuit hybrid simulation platform was developed based on Silvaco ATLAS. The validation of the model was obtained by calibrating it against commercially available HEMT data. Using this hybrid model, one can start with a two-dimensional (2D) drift-diffusion model of the device and build all the way up to its circuit implementation to evaluate its switching performance. The hybrid model offers an inexpensive and accurate way to project and benchmark the performance and can be extended to any GaN-based power transistors.In the experimental portion of this study, a high voltage OGFET was designed and fabricated. An OGFET shows improved characteristics owing to a 10 nm unintentionally doped (UID) GaN interlayer as the channel. A normally-off (V[subscript th] = 4 V) vertical GaN OGFET with 10 nm UID-GaN channel interlayer and 50 nm in-situ Al2O3 was successfully demonstrated and scaled for higher current operation. By using a novel double-field-plated structure for mitigating peak electric field, a higher off-state breakdown voltage over 1.4 kV was achieved with a significantly low specific on-state resistance (R[subscript on,sp]) of 2.2 m[omega] cm2. The metal-organic chemical vapor deposition (MOCVD) regrown 10 nm GaN channel interlayer enabled a channel resistance lower than 10 [omega] mm with an average channel electron mobility of 185 cm2/Vs. The fabricated large area transistor with a total area of 0.4 mm × 0.5 mm offered a breakdown voltage of 900 V and an Ron of 4.1 [omega]. Results indicate the potential of vertical GaN OGFET for greater than 1 kV range of power electronics applications.In addition to the OGFET, the CAVET with a trench gate structure was studied in this work. By taking advantage of the two-dimensional electron gas (2DEG) in the AlGaN/GaN structure, the trench CAVET can secure an even higher channel electron mobility compared to the OGFET. The first functional trench CAVET with a metal-insulator-semiconductor (MIS) gate structure was fabricated in this work with a breakdown voltage of about 225 V. With the improvement in the fabrication process, an 880 V device with an R[subscript on,sp] of 2.7 m[omega] cm2 was demonstrated. One of the notable features of the fabricated trench CAVET is that it requires a standard MOCVD growth condition for HEMT epilayers. The simplification of the growth process is a significant achievement. Finally, a regrowth-free CAVET was demonstrated and patented. The transformative approach was realized using Si ion implantation based doping compensation in the aperture.
Power Gan Devices
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Author : Matteo Meneghini
language : en
Publisher: Springer
Release Date : 2016-09-08
Power Gan Devices written by Matteo Meneghini and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-09-08 with Technology & Engineering categories.
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.
Design And Fabrication Of Vertical Gan Transistors For High Power And High Frequency Applications
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Author : Wenwen Li
language : en
Publisher:
Release Date : 2017
Design And Fabrication Of Vertical Gan Transistors For High Power And High Frequency Applications written by Wenwen Li and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Gallium nitride (GaN) is proving itself as the preferred material for high-power and high-frequency applications. Due to the increasing availability of bulk GaN substrates, vertical GaN transistors are coming to the forefront of research. Vertical structure is suitable for high-power applications as it minimizes surface-related dispersion issues prevailing in lateral high-electron-mobility transistors (HEMTs) and simultaneously provides a more economical solution for the same current rating. The two main devices studied and discussed in this thesis are Static Induction Transistors (SITs) and Metal Oxide Semiconductor Vertical Field Electron Transistors (MOSVFETs). Both structures are novel in their design with respect to GaN and relied on only GaN in their device structure. To achieve normally-off, high-voltage power switching, MOSVFET was designed and fabricated. Through proper design of the drift region thickness and doping parameters, an on-state resistance as low as 2.8 m[omega]·cm2 was achieved. The thesis also examines the effects of key parameters, such as electron mobility in the channel and in the bulk, gate to gate distance, and gate length on the on-state resistance, blocking voltage, and threshold voltage. Fully fabricated transistors were realized with different gate dielectrics. With SiN as the gate insulator, the gate was able to modulate the channel. However, with PEALD Al2O3 at the GaN and metal interface, the Fermi level pinning at the interface resulted in no modulation of the channel by the gate, and C-V measurement further verified this finding. MOCVD Al2O3 allowed the best possible gate modulation indicating substantially lower interface states. SIT (static induction transistor) looks similar to a MOSVFET where a Schottky structure is used as the gate instead of an oxide layer. In a way, an SIT acts as a predecessor of a MOSVFET and needs no oxide or p-type GaN for its functioning. GaN SIT using the self-aligned technology was accomplished using a SiO2 lift-off step in buffered oxide etching (BOE). The low power dry etching combined with wet etching was proved to be effective in reducing the etch damages, decreasing the gate leakage, and enhancing the gate control over the channel. Finally, a photoresist planarization-assisted method was developed which achieved a MOSVFET with more than 8 kA/cm2 of output current, 0.57 m[omega]·cm2 of on-state resistance, and higher-quality oxide.
Gan Transistors For Efficient Power Conversion
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Author : Alex Lidow
language : en
Publisher: John Wiley & Sons
Release Date : 2019-08-12
Gan Transistors For Efficient Power Conversion written by Alex Lidow and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-08-12 with Science categories.
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.
Fabrication And Characterization Of Gan Based Lateral And Vertical Transistors For Switching Applications
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Author : Yidi Yin
language : en
Publisher:
Release Date : 2022
Fabrication And Characterization Of Gan Based Lateral And Vertical Transistors For Switching Applications written by Yidi Yin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
Modeling And Simulation Of Gan Based High Electron Mobility Transistors
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Author : Elias W. Faraclas
language : en
Publisher:
Release Date : 2006
Modeling And Simulation Of Gan Based High Electron Mobility Transistors written by Elias W. Faraclas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
Design Fabrication And Characterization Of Gan Based Devices For Power Applications
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Author : Burcu Ercan
language : en
Publisher:
Release Date : 2020
Design Fabrication And Characterization Of Gan Based Devices For Power Applications written by Burcu Ercan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Gallium Nitride (GaN) and related alloys have gained considerable momentum in recent years since the improvement in silicon (Si) based power devices is now only incremental. GaN is a promising material for high-power, high-frequency applications due to its wide bandgap, high carrier mobility which result in devices with high breakdown voltage, low on-resistance, and high temperature stability. Despite the superior properties of GaN there is still room for improvement in device design and fabrication to reach theoretical limits of GaN based devices. Reaching the theoretical critical electric field in GaN devices has been challenging due to the presence of threading dislocations, surface impurities introduced during material growth and fabrication process. In order to prevent premature breakdown of the devices, these defects must be mitigated. In this study, avalanche breakdown was observed in p-n diodes fabricated with low power reactive ion etch with a moat etch profile, followed by Mg ion implantation to passivate the plasma damages. Additionally, the devices were fabricated on free standing GaN substrates which has lower dislocation than sapphire or SiC substrates. The electron and hole impact ionization coefficients were extracted separately by analyzing the ultraviolet (UV) assisted reverse bias current voltage measurements of vertical p-n and n-p diodes. GaN and related alloy such as Indium Aluminum Nitride (InAlN) or Aluminum Gallium Nitride (AlGaN) form a high mobility, high density sheet charge at the heterojunction. High electron mobility transistor (HEMT) devices fabricated on these layer stacks are depletion mode (normally-on) devices with a negative threshold voltage. However, normally-on devices are not preferred in power applications due to safety reasons and to reduce the external circuitry. Therefore, the development of an enhancement mode (normally-off) GaN based high electron mobility transistors (HEMT) with positive threshold voltage is important for next generation power devices. Several methods, such as growing a p-GaN on the barrier layer, recessed gate by dry etching, plasma treatment under the gate have been previously studied to develop enhancement-mode HEMT devices. In this study, MOS-HEMT devices were fabricated by selective thermal oxidation of InAlN to reduce InAlN barrier thickness under the gate contact. The thermal oxidation of InAlN occurs at temperatures above 600°C, while GaN oxidation occurs above 1000°C at a slow rate which allows the decrease of the InAlN barrier layer thickness under the gate in a reliable way due to the self-limiting nature of oxidation. A positive shift in the threshold voltage and a reduction in reverse leakage current was demonstrated on MOS-diode structures by thermally oxidizing InAlN layers with In composition of 0.17, 0.178 and 0.255 for increasing oxidation durations at 700°C and 800°C. Enhancement mode device operation was demonstrated on lattice matched InAlN/AlN/GaN/Sapphire MOS-HEMT devices by selective thermal oxidation of InAlN layer under the gate contact. A positive threshold voltage was observed for devices which were subjected to thermal oxidation at 700°C for 10, 30 and 60 minutes. The highest threshold voltage was observed as 1.16 V for the device that was oxidized for 30 minutes at 700°C. The maximum transconductance and the maximum drain saturation current of this device was 4.27 mS/mm and 150 mA/mm, respectively.
Gan Based Vertical Power Devices
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Author : Yuhao Zhang (Ph. D.)
language : en
Publisher:
Release Date : 2017
Gan Based Vertical Power Devices written by Yuhao Zhang (Ph. D.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Power electronics based on Gallium Nitride (GaN) is expected to significantly reduce the losses in power conversion circuits and increase the power density. This makes GaN devices very exciting candidates for next-generation power electronics, for the applications in electric vehicles, data centers, high-power and high-frequency communications. Currently, both lateral and vertical structures are considered for GaN power devices. In particular, vertical GaN power devices have attracted significant attention recently, due to the potential for achieving high breakdown voltage and current levels without enlarging the chip size. In addition, these vertical devices show superior thermal performance than their lateral counterparts. This PhD thesis addresses several key obstacles in developing vertical GaN power devices. The commercialization of vertical GaN power devices has been hindered by the high cost of bulk GaN. The first project in this PhD thesis demonstrated the feasibility of making vertical devices on a low-cost silicon (Si) substrate for the first time. The demonstrated high performance shows the great potential of low-cost vertical GaN-on-Si devices for 600-V level high-current and high-power applications. This thesis has also studied the origin of the off-state leakage current in vertical GaN pn diodes on Si, sapphire and GaN substrates, by experiments, analytical calculations and TCAD simulations. Variable-range-hopping through threading dislocations was identified as the main off-state leakage mechanism in these devices. The design space of leakage current of vertical GaN devices has been subsequently derived. Thirdly, a novel GaN vertical Schottky rectifier with trench MIS structures and trench field rings was demonstrated. The new structure greatly enhanced the reverse blocking characteristics while maintaining a Schottky-like good forward conduction. This new device shows great potential for using advanced vertical Schottky rectifiers for high-power and high-frequency applications. Finally, we investigated a fundamental and significant challenge for GaN power devices: the lack of reliable and generally useable patterned pn junctions. Two approaches have been proposed to make lateral patterned pn junctions. Two devices, junction barrier Schottky devices and super-junction devices, have been designed and optimized. Preliminary experimental results were also demonstrated for the feasibility of making patterned pn junctions and fabricating novel power devices.
Wide Bandgap Based Devices
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Author : Farid Medjdoub
language : en
Publisher: MDPI
Release Date : 2021-05-26
Wide Bandgap Based Devices written by Farid Medjdoub and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-05-26 with Technology & Engineering categories.
Emerging wide bandgap (WBG) semiconductors hold the potential to advance the global industry in the same way that, more than 50 years ago, the invention of the silicon (Si) chip enabled the modern computer era. SiC- and GaN-based devices are starting to become more commercially available. Smaller, faster, and more efficient than their counterpart Si-based components, these WBG devices also offer greater expected reliability in tougher operating conditions. Furthermore, in this frame, a new class of microelectronic-grade semiconducting materials that have an even larger bandgap than the previously established wide bandgap semiconductors, such as GaN and SiC, have been created, and are thus referred to as “ultra-wide bandgap” materials. These materials, which include AlGaN, AlN, diamond, Ga2O3, and BN, offer theoretically superior properties, including a higher critical breakdown field, higher temperature operation, and potentially higher radiation tolerance. These attributes, in turn, make it possible to use revolutionary new devices for extreme environments, such as high-efficiency power transistors, because of the improved Baliga figure of merit, ultra-high voltage pulsed power switches, high-efficiency UV-LEDs, and electronics. This Special Issue aims to collect high quality research papers, short communications, and review articles that focus on wide bandgap device design, fabrication, and advanced characterization. The Special Issue will also publish selected papers from the 43rd Workshop on Compound Semiconductor Devices and Integrated Circuits, held in France (WOCSDICE 2019), which brings together scientists and engineers working in the area of III–V, and other compound semiconductor devices and integrated circuits. In particular, the following topics are addressed: – GaN- and SiC-based devices for power and optoelectronic applications – Ga2O3 substrate development, and Ga2O3 thin film growth, doping, and devices – AlN-based emerging material and devices – BN epitaxial growth, characterization, and devices