Date of Award

2018-01-01

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Advisor(s)

Ramana V. Chintalapalle

Abstract

The existing power generation systems, which utilize fossil fuels, are in dire need of efficient, reliable chemical sensors that can operate safely at higher temperatures. These sensors control the combustion environment and the emissions during combustion. Several sensing materials such as SnO2, ZnO, TiO2, WO3, and Ga2O3 exhibit high sensitivity to certain type of chemical molecules and in a certain range of temperatures. Among these candidate materials, β-Ga2O3 is stable at very high temperatures and has shown functionality for oxygen sensing at higher temperatures (>700°C). However, the response time and sensitivity must be significantly improved in order to derive their full potential and utilize them in practical applications. In this work, we focus on the fabrication, characterization and performance evaluation of titanium (Ti) doped gallium oxide (Ga2O3) thin films (referred to GTO) for application in oxygen sensors. An in-depth study was performed on GTO sensors to improve response time and sensitivity of β-Ga2O3. The real environment condition for sensor (>700°C) application were simulated to understand the effect of temperature on the crystal structure, mechanical properties, electronic properties and oxidation states of Ti doped β-Ga2O3. Additionally, for utilizing Ti doped β-Ga2O3 films in practical oxygen sensor applications, attempts were also made to predict the thermodynamic stability and performance of a model, doped Ga2O3 system under extreme environments. A detailed thermal study to understand the effect of extreme environment on titanium (Ti) doped β-Ga2O3 is performed. The real environment condition for sensor (>700°C) application was simulated to understand the effect of temperature on the crystal structure, mechanical properties, electronic properties and oxidation states of Ti doped β-Ga2O3. In the entire work, a wide variety of analytical techniques were employed to derive conclusions on the structure, morphology, chemical states, optical properties, thermo-chemical and thermo-mechanical stability of nanostructured Ti-doped Ga2O3. The results are presented and discussed in this thesis along with structure-property relationships and implications for sensor technology.

Language

en

Provenance

Received from ProQuest

File Size

113 pages

File Format

application/pdf

Rights Holder

Sandeep Manandhar

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