Design and development of radiation-resistant and low-noise semiconductor transistors for applications in high frequency communication systems
type: CreativeWork
description: In the frame of this work, the fundamental properties of GaN/AlGaN HEMT structures have been investigated in order to optimize their performance in high power microwave devices. A number of properties have been studied, starting from DC transport properties in bare 2DEG channels up to investigation of phase noise of a X-band HEMT-based oscillator. This work is separated into five parts. In the first part, basics of fluctuation phenomena in semiconductors are described along with a discussion of theoretical models, which are most applicable in case of investigation of noise in HEMT devices. In the second part, a study of 2DEG transport at low and moderate electric fields is performed. The gateless TLM structures have been suggested for adequate analysis of the transport effects. The observed current saturation through a TLM structure confirms that both thermal overheating and hot electron effects are influencing the current. A theoretical model has been developed for the separate investigation of both relevant effects. We performed microsecond pulse measurements that show a 60% reduction of self-heating influence compared to DC measurements, which is in agreement with our calculations. In order to remove Joule heating effects and to investigate only the fundamental transport properties, a nanosecond pulse measurement technique was developed. By applying 10-30 ns electrical pulses to AlGaN/GaN gateless heterostructures, we experimentally measured low ?eld and high ?eld transport phenomena, including the drift velocity dependence on the applied electric ?eld up to the record height of 150 kV/cm for GaN-based heterostructures. Besides the self-heating, another strong limitation of high frequency devices is low- frequency noise. In the third part, an adequate method for the low-frequency noise sources characterisation from different device regions is proposed and tested for nanoscale Group-III- nitride heterostructures. The temperature dependence of the noise revealed a …
abstract: In the frame of this work, the fundamental properties of GaN/AlGaN HEMT structures have been investigated in order to optimize their performance in high power microwave devices. A number of properties have been studied, starting from DC transport properties in bare 2DEG channels up to investigation of phase noise of a X-band HEMT-based oscillator. This work is separated into five parts. In the first part, basics of fluctuation phenomena in semiconductors are described along with a discussion of theoretical models, which are most applicable in case of investigation of noise in HEMT devices. In the second part, a study of 2DEG transport at low and moderate electric fields is performed. The gateless TLM structures have been suggested for adequate analysis of the transport effects. The observed current saturation through a TLM structure confirms that both thermal overheating and hot electron effects are influencing the current. A theoretical model has been developed for the separate investigation of both relevant effects. We performed microsecond pulse measurements that show a 60% reduction of self-heating influence compared to DC measurements, which is in agreement with our calculations. In order to remove Joule heating effects and to investigate only the fundamental transport properties, a nanosecond pulse measurement technique was developed. By applying 10-30 ns electrical pulses to AlGaN/GaN gateless heterostructures, we experimentally measured low ?eld and high ?eld transport phenomena, including the drift velocity dependence on the applied electric ?eld up to the record height of 150 kV/cm for GaN-based heterostructures. Besides the self-heating, another strong limitation of high frequency devices is low- frequency noise. In the third part, an adequate method for the low-frequency noise sources characterisation from different device regions is proposed and tested for nanoscale Group-III- nitride heterostructures. The temperature dependence of the noise revealed a …
author: Danylyuk, Serhiy
language: eng
keywords: info:eu-repo/classification/ddc/530, HEMT, Heterostruktur-Bauelement, Galliumnitrid, Aluminiumnitrid, Elektronischer Transport, Rauscheigenschaft, Physik, Wide band gap semiconductors, 1/f noise, phase noise, loop oscillators, III-Nitride heterostructures, hot electron effects
date published: 2004
date modified: 2026-07-30T19:43:19Z
provider: RWTH Aachen University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Publikationsserver der RWTH Aachen University