Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability

Bibliographic Details
Main Author:	Sun, Wenyuan
Language:	English
Published:	The Ohio State University / OhioLINK 2020
Subjects:	Electrical Engineering
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=osu1586989454689707

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-osu15869894546897072021-08-03T07:14:29Z Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability Sun, Wenyuan Electrical Engineering GaN-based transistors have been widely used in RF and power industries due to its promising properties including high breakdown voltage, high switching frequency, large saturation current, high operation temperature and high radiation tolerance, etc. GaN shows superior Johnson’s Figure of Merit, which is a widely used indicator of high-frequency and high-power applications, as well as Baliga’s Figure of Merit, which is an indicator primarily used of high power applications, comparing to its competitors such as Si, GaAs and SiC. This dissertation focuses on the impact of traps on GaN-based transistors. Multiple techniques were used in this dissertation to characterize devices and traps. Double pulsed I-V measurements were used to examine the direct impact of trapping effects on device terminal characteristics at different biasing conditions. Constant drain-voltage deep level transient spectroscopy and isothermal VT transient spectroscopy (developed in this study) were used to identify traps directly in transistors. Conventional deep level transient spectroscopy and deep level optical spectroscopy were used to study traps in material level. Silvaco TCAD simulation and Monte-Carlo simulation were used to model the trap filling and emission processes and explain the trap related mechanisms.In power AlGaN/GaN MISHEMTs, an EC-0.90 eV trap in GaN layer was found to cause a large negative threshold voltage shift at HV pinch-off condition with VDS = 600 V, and also a positive threshold voltage shift at HV semi-on condition with VDS = 600 V & IDS = 1 mA. The negative voltage shift is due to the thermal emission of the EC-0.90 eV trap in the depletion region induced by the large gate drain voltage, while the positive threshold voltage shift is due to the filling process of the EC 0.90 eV trap with electrons provided by hot-carrier effect. Therefore, it was suggested that mitigating the EC-0.90 eV trap in the buffer should be able to improve the threshold voltage stability of the device. Then, in RF AlGaN/GaN HEMTs, an EC-0.57 eV trap was found to mainly degrade the Adjacent Channel Power Ratio of the device at frequency division duplex, while an EC-0.72 eV trap was found to primarily degrade the ACPR at time division duplex. Both traps are in the GaN layer and the EC-0.57 eV trap was previously reported to be iron-related, thus the RF performance of the device is expected to be improved through reducing the iron doping concentration or moving the iron doped layer away from the conducting channel. At the end, the impacts of irradiations on GaN devices were studied. It was found that proton and neutron irradiation can cause permanent positive threshold voltage shift by creating deep acceptor-like traps in GaN, while electron irradiation can cause permanent negative threshold voltage shift by creating shallow donor like traps in GaN. An analytic model was developed to predict the irradiation damage on GaN transistors based on the compensating rate of the irradiation particle and the radiated device structure. It is suggested by the model that the radiation hardness of the device can be improved by reducing the barriers thickness or increasing the initial buffer doping. 2020-10-01 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1586989454689707 http://rave.ohiolink.edu/etdc/view?acc_num=osu1586989454689707 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Electrical Engineering
spellingShingle	Electrical Engineering Sun, Wenyuan Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability
author	Sun, Wenyuan
author_facet	Sun, Wenyuan
author_sort	Sun, Wenyuan
title	Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability
title_short	Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability
title_full	Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability
title_fullStr	Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability
title_full_unstemmed	Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability
title_sort	impact of as-grown and radiation-induced traps on gan rf and power transistor performance and reliability
publisher	The Ohio State University / OhioLINK
publishDate	2020
url	http://rave.ohiolink.edu/etdc/view?acc_num=osu1586989454689707
work_keys_str_mv	AT sunwenyuan impactofasgrownandradiationinducedtrapsonganrfandpowertransistorperformanceandreliability
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Impact of As-grown and Radiation-induced Traps on GaN RF and Power Transistor Performance and Reliability

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