Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2018
Student: GÖKHAN ATMACA
Supervisor: SEFER BORA LİŞESİVDİN
Abstract:AlGaN/GaN heterostructures have a widely usage area in high power, high frequency and high temperature applications for modern electronics. Despite of this widely usage area, AlGaN/GaN based electronics devices have some problems during the operation. One of these problems is current collapse in current-voltage characteristics. For long years, Si3N4 surface passivation is used in surface of heterostructure to prevent current collapse. Because electrons trapped by surface states in surface leads to current collapse and this passivation layer reduces surface states in surface. Therefore, number of trapped electrons is decreased and current collapse is suppressed at certain amount. Low-field transport and hot-electron transport investigations can play an important role in better understanding the behind mechanisms of this method widely used in high power and high frequency electronics devices. In this thesis study, the effect of Si3N4 passivation layer on two dimensional electron gas in AlGaN/GaN heterostructures is investigated with temperature dependent Hall effect and hot-electron dynamics measurements of different sample groups. In low-field transport investigations, since carrier density is increased with surface passivation, it was found that effect of interface roughness scattering mechanism on mobility is increased. In analyses with hot-electron dynamics measurements, the experimental observation of the negative differential resistance phenomena in drift velocity-electric field characteristics of AlGaN/GaN heterostructures was firstly achieved.