Design And Fabrication Of Vertical Gan Transistors For High Power And High Frequency Applications

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Design and Fabrication of Vertical GaN Transistors for High-power and High-frequency Applications

Author : Wenwen Li
Publisher :
ISBN 13 : 9780355764277
Total Pages : pages
Book Rating : 4.7/5 (642 download)

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Book Synopsis Design and Fabrication of Vertical GaN Transistors for High-power and High-frequency Applications by : Wenwen Li

Download or read book Design and Fabrication of Vertical GaN Transistors for High-power and High-frequency Applications written by Wenwen Li and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Design and Fabrication of Nitrogen Polar Gallium Nitride Vertical Transistors for High-power and High-frequency Applications

Author : Saba Rajabi
Publisher :
ISBN 13 : 9781085572613
Total Pages : pages
Book Rating : 4.5/5 (726 download)

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Book Synopsis Design and Fabrication of Nitrogen Polar Gallium Nitride Vertical Transistors for High-power and High-frequency Applications by : Saba Rajabi

Download or read book Design and Fabrication of Nitrogen Polar Gallium Nitride Vertical Transistors for High-power and High-frequency Applications written by Saba Rajabi and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Gallium nitride (GaN) has remarkable potential to extend the silicon-based semiconductor industry, which is currently plateauing in performance due to its materials limits Any significant improvement comes with a price that may not be a sustainable way to support the need for next generation electronic devices. With a more efficient semiconductor, such as a GaN, engineers could design and fabricate compact devices with ultra-high-scale density, because of GaN’s high electric field strength, saturation velocity, and electron mobility. Studies have already indicated that GaN device technology has tremendous potential for high-frequency communications and photonic applications. Because of advances in growth on commercially feasible large-area substrates, high radio frequency (RF) power applications of GaN are approaching commercialization. The basic material properties of GaN translate to smaller devices, which can lead to higher operation frequencies and lower switching losses. At the same time, the component count and size of passives has decreased. To date, most reported GaN-based field effect transistors have been in a Gallium polar (Ga-polar) orientation. Recent reports have suggested that Nitrogen polar (N-polar) GaN device technology is highly attractive for high RF power applications. The reverse polarization field in N-polar GaN compared to Ga-polar GaN promises unique design advantages. For example, an Al(Ga)N back barrier induces two-dimensional electron gas (2DEG) in the GaN channel and simultaneously confines electrons into the channel. Because of improved electron confinement in the channel and the higher aspect ratio, N-polar devices can presumably achieve superior performance. Additionally, N-polar devices offer lower specific contact resistance since the contacts to the 2DEG occur through GaN rather than wider-bandgap AlGaN material, which is necessary in Ga-polar devices. Previous results have clearly established that vertical devices in the form of current aperture vertical electron transistors (CAVETs) produce dispersion-less output current-voltage (IV) characteristics with a higher blocking electric field than that of lateral devices. The electric field being buried in the bulk of the material is helpful to achieve dispersion-less output characteristics compared to high electron mobility transistors (HEMTs), where surface states cause “knee walkout” or current collapse under high frequencies. Therefore, merging a N-polar high aspect ratio channel with a vertical drift region, as a CAVET does, is an attractive design to accomplish higher RF power performance compared to lateral counterparts. An integral part of a CAVET is the current blocking layer (CBL), which blocks the current flow from all paths except the aperture. Ga-polar CAVETs have been developed with either a Mg-doped GaN CBL or [Mg2+] ion-implanted GaN CBL. The latter is an attractive technique since it can alleviate regrowth in trenches. Notably, Mg ions diffuse out during the channel regrowth process at high temperatures. An AlN interlayer with a thickness of less than a nanometer is an effective solution to stop Mg ions from diffusing out into the channel layer and thereby causing uncontrollable threshold voltage shifts. It is crucial to mention that an AlN back barrier is an essential part of the structure of a vertical N-polar device design, as it is necessary to form the 2DEG channel as well as a diffusion barrier to arrest Mg out-diffusion. Thus, it renders N-polar vertical devices an especially appealing class of devices for RF application.This dissertation aims to provide a physical understanding and insight regarding the N-polar CAVET as well as the device’s design, performance and thermal analysis.

Power GaN Devices

Author : Matteo Meneghini
Publisher : Springer
ISBN 13 : 3319431994
Total Pages : 383 pages
Book Rating : 4.3/5 (194 download)

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Book Synopsis Power GaN Devices by : Matteo Meneghini

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.

GaN Technology

Author : Maurizio Di Paolo Emilio
Publisher : Springer Nature
ISBN 13 : 3031632389
Total Pages : 388 pages
Book Rating : 4.0/5 (316 download)

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Book Synopsis GaN Technology by : Maurizio Di Paolo Emilio

Download or read book GaN Technology written by Maurizio Di Paolo Emilio and published by Springer Nature. This book was released on with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Design and Development of GaN-based Vertical Transistors for Increased Power Density in Power Electronics Applications

Author : Dong Ji
Publisher :
ISBN 13 : 9780355764284
Total Pages : pages
Book Rating : 4.7/5 (642 download)

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Book Synopsis Design and Development of GaN-based Vertical Transistors for Increased Power Density in Power Electronics Applications by : Dong Ji

Download or read book Design and Development of GaN-based Vertical Transistors for Increased Power Density in Power Electronics Applications written by Dong Ji and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

GaN Transistors for Efficient Power Conversion

Author : Alex Lidow
Publisher : John Wiley & Sons
ISBN 13 : 1118844769
Total Pages : 266 pages
Book Rating : 4.1/5 (188 download)

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Book Synopsis GaN Transistors for Efficient Power Conversion by : Alex Lidow

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 2014-09-15 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gallium nitride (GaN) is an emerging technology that promises to displace silicon MOSFETs in the next generation of power transistors. As silicon approaches its performance limits, GaN devices offer superior conductivity and switching characteristics, allowing designers to greatly reduce system power losses, size, weight, and cost. This timely second edition 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. With higher-frequency switching capabilities, GaN devices offer the chance to increase efficiency in existing applications such as DC–DC conversion, while opening possibilities for new applications including wireless power transfer and envelope tracking. This book is an essential learning tool and reference guide to enable power conversion engineers to design energy-efficient, smaller and more cost-effective products using GaN transistors. Key features: Written by leaders in the power semiconductor field and industry pioneers in GaN power transistor technology and applications. Contains useful discussions on device–circuit interactions, which are highly valuable since the new and high performance GaN power transistors require thoughtfully designed drive/control circuits in order to fully achieve their performance potential. Features practical guidance on formulating specific circuit designs when constructing power conversion systems using GaN transistors – see companion website for further details. A valuable learning resource for professional engineers and systems designers needing to fully understand new devices as well as electrical engineering students.

GaN-based Vertical Power Devices

Author : Yuhao Zhang (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : 170 pages
Book Rating : 4.:/5 (1 download)

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Book Synopsis GaN-based Vertical Power Devices by : Yuhao Zhang (Ph. D.)

Download or read book GaN-based Vertical Power Devices written by Yuhao Zhang (Ph. D.) and published by . This book was released on 2017 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Gallium Nitride (GaN)

Author : Farid Medjdoub
Publisher : CRC Press
ISBN 13 : 1482220040
Total Pages : 372 pages
Book Rating : 4.4/5 (822 download)

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Book Synopsis Gallium Nitride (GaN) by : Farid Medjdoub

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.

Novel Gallium Nitride Transistor Architectures for Wireless Communications and Power Electronics

Author : Woojin Choi
Publisher :
ISBN 13 :
Total Pages : 121 pages
Book Rating : 4.:/5 (119 download)

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Book Synopsis Novel Gallium Nitride Transistor Architectures for Wireless Communications and Power Electronics by : Woojin Choi

Download or read book Novel Gallium Nitride Transistor Architectures for Wireless Communications and Power Electronics written by Woojin Choi and published by . This book was released on 2020 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transistors are the backbone of any electronic system. The Si complementary metal-oxide-semiconductor (CMOS) technology with extremely scaled process has governed the electronic world in the last few decades, but many other materials with novel design architectures are emerging to alternate it in some applications. Gallium nitride (GaN) is one of them and coming into view recently for high power and high frequency applications due to the surge of electric power usage and data transmission rate. This dissertation provides a comprehensive study of two types of GaN transistors, lateral and vertical, for power electronics and wireless communications. The first half of the dissertation investigates vertical GaN transistors for high power switches. The epitaxial layers grown by a novel selective area growth (SAG) method on a Si substrate were utilized to pursue demonstration of cheap and high-performance GaN devices, and commercialized GaN wafers were used to identify and resolve existing problems, and to improve the key device metrics. An evolution of the vertical GaN transistor by optimizing the device design and the fabrication process is shown and discussed in detail with experiments and TCAD simulations. In the second half of this dissertation, we propose a novel approach to address the intrinsic linearity of GaN transistors for radio frequency (RF) amplifiers. A new device design methodology was presented by simple lithographic modifications that can create a flat transconductance (gm) profile for AlGaN/GaN Fin field-effect transistors (FinFETs). Then, it is discussed how this flat gm impacts on the intermodulation distortion characteristics at microwave as well as millimeter wave frequencies with a record linearity figure-of-merit at 5 GHz. Finally, with a measured noise performance of the realized device, we present a record dynamic range figure-of-merit at 30 GHz for GaN transistors and much higher linearity performance than any existing semiconductor technologies, exhibiting a great potential for mm-wave low noise amplifiers (LNAs).

Wide Bandgap Based Devices

Author : Farid Medjdoub
Publisher : MDPI
ISBN 13 : 3036505660
Total Pages : 242 pages
Book Rating : 4.0/5 (365 download)

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Book Synopsis Wide Bandgap Based Devices by : Farid Medjdoub

Download or read book Wide Bandgap Based Devices written by Farid Medjdoub and published by MDPI. This book was released on 2021-05-26 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Gallium Nitride-enabled High Frequency and High Efficiency Power Conversion

Author : Gaudenzio Meneghesso
Publisher : Springer
ISBN 13 : 331977994X
Total Pages : 242 pages
Book Rating : 4.3/5 (197 download)

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Book Synopsis Gallium Nitride-enabled High Frequency and High Efficiency Power Conversion by : Gaudenzio Meneghesso

Download or read book Gallium Nitride-enabled High Frequency and High Efficiency Power Conversion written by Gaudenzio Meneghesso and published by Springer. This book was released on 2018-05-12 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book demonstrates to readers why Gallium Nitride (GaN) transistors have a superior performance as compared to the already mature Silicon technology. The new GaN-based transistors here described enable both high frequency and high efficiency power conversion, leading to smaller and more efficient power systems. Coverage includes i) GaN substrates and device physics; ii) innovative GaN -transistors structure (lateral and vertical); iii) reliability and robustness of GaN-power transistors; iv) impact of parasitic on GaN based power conversion, v) new power converter architectures and vi) GaN in switched mode power conversion. Provides single-source reference to Gallium Nitride (GaN)-based technologies, from the material level to circuit level, both for power conversions architectures and switched mode power amplifiers; Demonstrates how GaN is a superior technology for switching devices, enabling both high frequency, high efficiency and lower cost power conversion; Enables design of smaller, cheaper and more efficient power supplies.

An Investigation Into Fabrication Technologies for Vertical GaN Devices

Author : Azlan Baharin
Publisher :
ISBN 13 :
Total Pages : 320 pages
Book Rating : 4.:/5 (813 download)

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Book Synopsis An Investigation Into Fabrication Technologies for Vertical GaN Devices by : Azlan Baharin

Download or read book An Investigation Into Fabrication Technologies for Vertical GaN Devices written by Azlan Baharin and published by . This book was released on 2011 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] Vertical transistors using GaN have significant advantages over planar devices in high power, high current applications. The principal focus of this thesis is to use the GaN n-p vertical diode as a model to understand the fabrication issues involved in vertical transistors. GaN n-p vertical diodes have been fabricated using Si ion implantation into p-doped material on a p+-buried layer. Ion implantation is widely used in semiconductor device technology because it offers precise control of the concentration and depth of dopants that are inserted in a specific area of the wafer and the technique can be easily applied to batch processing; GaN implantation technology is still in the developing phase and it is hoped that not too far in the future, ion implantation can also become a practical process for GaN-based devices. Amongst the major challenges faced for ion implantation in GaN is the extremely high and impractical annealing temperature (above 1500 °C) required for a complete recovery of implantation damage. This work has shown that a much lower annealing temperature of 1260 °C can be sufficient to minimise the damage and electrically activate the implanted dopants. In the first round of device fabrication, vertical diodes were successfully obtained using Si implantation with a variety of energies and doses. Although the performance was poor, with non-ohmic contacts to the buried p+-layer and a high turn on voltage of about 10 V, an active n-p junction was achieved with blue light emission when biased in the forward direction. However, the active area was restricted to the periphery of the circular devices. It was initially proposed that a likely cause for the low performance of the initial devices is related to the damage introduced to the p+-layers by plasma etching as well as insufficient activation of the Mg-doped GaN in the buried layer. Thus, further investigation into improving the quality of contacts to the etched-surface and activation of p-GaN buried layer were essential requisites, prior to fabricating a second round of vertical devices. Investigation into these two factors is also applicable to enhance the processing techniques of p-GaN based devices. Amongst the major issues with the processing of buried p-GaN layers is obtaining good ohmic contacts...

Fabrication of Graphene-on-GaN Vertical Transistors

Author : Ahmad Zubair (S.M.)
Publisher :
ISBN 13 :
Total Pages : 63 pages
Book Rating : 4.:/5 (899 download)

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Book Synopsis Fabrication of Graphene-on-GaN Vertical Transistors by : Ahmad Zubair (S.M.)

Download or read book Fabrication of Graphene-on-GaN Vertical Transistors written by Ahmad Zubair (S.M.) and published by . This book was released on 2014 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The excellent transport properties of graphene make it an excellent option for very high frequency electronics. However, the poor output resistance and difficult lithography of lateral transistors significantly limit its performance. In this thesis, we propose a new kind of vertical graphene base transistor to take advantage of both wide bandgap GaN semiconductors and zero bandgap graphene for high frequency transistors. This majority-carrier device has a metal collector, a graphene base and an AlGaN/GaN emitter. The first device prototype exhibits very promising current density(~mA/cm 2 ) and current gain ([alpha] ~ 50 %). Simulations further support that with proper optimization of the materials and device structure, the proposed transistor can be a promising candidate for future high frequency applications.

Design, Fabrication and Characterization of GaN-based Devices for Power Applications

Author : Burcu Ercan
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.5/5 (825 download)

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Book Synopsis Design, Fabrication and Characterization of GaN-based Devices for Power Applications by : Burcu Ercan

Download or read book Design, Fabrication and Characterization of GaN-based Devices for Power Applications written by Burcu Ercan and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Gallium Nitride Power Devices

Author : Hongyu Yu
Publisher : CRC Press
ISBN 13 : 1351767615
Total Pages : 298 pages
Book Rating : 4.3/5 (517 download)

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Book Synopsis Gallium Nitride Power Devices by : Hongyu Yu

Download or read book Gallium Nitride Power Devices written by Hongyu Yu and published by CRC Press. This book was released on 2017-07-06 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: GaN is considered the most promising material candidate in next-generation power device applications, owing to its unique material properties, for example, bandgap, high breakdown field, and high electron mobility. Therefore, GaN power device technologies are listed as the top priority to be developed in many countries, including the United States, the European Union, Japan, and China. This book presents a comprehensive overview of GaN power device technologies, for example, material growth, property analysis, device structure design, fabrication process, reliability, failure analysis, and packaging. It provides useful information to both students and researchers in academic and related industries working on GaN power devices. GaN wafer growth technology is from Enkris Semiconductor, currently one of the leading players in commercial GaN wafers. Chapters 3 and 7, on the GaN transistor fabrication process and GaN vertical power devices, are edited by Dr. Zhihong Liu, who has been working on GaN devices for more than ten years. Chapters 2 and 5, on the characteristics of polarization effects and the original demonstration of AlGaN/GaN heterojunction field-effect transistors, are written by researchers from Southwest Jiaotong University. Chapters 6, 8, and 9, on surface passivation, reliability, and package technologies, are edited by a group of researchers from the Southern University of Science and Technology of China.

Simulation and Fabrication of GaN-based Vertical and Lateral Normally-off Power Transistors

Author : Yuhao Zhang (S.M.)
Publisher :
ISBN 13 :
Total Pages : 98 pages
Book Rating : 4.:/5 (861 download)

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Book Synopsis Simulation and Fabrication of GaN-based Vertical and Lateral Normally-off Power Transistors by : Yuhao Zhang (S.M.)

Download or read book Simulation and Fabrication of GaN-based Vertical and Lateral Normally-off Power Transistors written by Yuhao Zhang (S.M.) and published by . This book was released on 2013 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Vertical GaN and SiC Power Devices

Author : Kazuhiro Mochizuki
Publisher : Artech House
ISBN 13 : 1630814296
Total Pages : 284 pages
Book Rating : 4.6/5 (38 download)

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Book Synopsis Vertical GaN and SiC Power Devices by : Kazuhiro Mochizuki

Download or read book Vertical GaN and SiC Power Devices written by Kazuhiro Mochizuki and published by Artech House. This book was released on 2018-04-30 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique new resource provides a comparative introduction to vertical Gallium Nitride (GaN) and Silicon Carbide (SiC) power devices using real commercial device data, computer, and physical models. This book uses commercial examples from recent years and presents the design features of various GaN and SiC power components and devices. Vertical verses lateral power semiconductor devices are explored, including those based on wide bandgap materials. The abstract concepts of solid state physics as they relate to solid state devices are explained with particular emphasis on power solid state devices. Details about the effects of photon recycling are presented, including an explanation of the phenomenon of the family tree of photon-recycling. This book offers in-depth coverage of bulk crystal growth of GaN, including hydride vapor-phase epitaxial (HVPE) growth, high-pressure nitrogen solution growth, sodium-flux growth, ammonothermal growth, and sublimation growth of SiC. The fabrication process, including ion implantation, diffusion, oxidation, metallization, and passivation is explained. The book provides details about metal-semiconductor contact, unipolar power diodes, and metal-insulator-semiconductor (MIS) capacitors. Bipolar power diodes, power switching devices, and edge terminations are also covered in this resource.