Graduation Semester and Year

2012

Language

English

Document Type

Thesis

Degree Name

Master of Science in Materials Science and Engineering

Department

Materials Science and Engineering

First Advisor

Efstathios Meletis

Abstract

Titanium dioxide (TiO2) is considered as an oxide semiconductor with several unique properties, including environmental sensing capabilities, biocompatibility and photocurrent generation, long-term stability, cost efficiency, and chemical inertness. TiO2 thin films have a wide range of applications in dye-sensitized solar cells. TiO2 films have been deposited on two different substrates, aluminum and titanium. Two different methods used for deposition of the thin films namely: Plasma Electrolytic Oxidation (PEO) and Physical Vapor Deposition (PVD). In order to study the effect of roughness of the substrate on photocurrent generation of the deposited films, one group of substrates were “patterned” by Electrolytic Plasma Processing (EPP) prior to deposition. A “hill and valley” morphology was observed on the uppermost layer of the EPP-treated substrates. The microstructure and also roughness of the EPP-treated substrates were characterized by Scanning Electron Microscopy (SEM) and Profilometry. Similarly, the deposited TiO2 thin films were also characterized by SEM, Energy Dispersive Spectroscopy (EDS), Raman, Transmission Electron Microscopy (TEM), X-ray Diffractometry (XRD), and Profilometry. It was found that the PEO deposited film on titanium substrate was composed of anatase and the film on the aluminum substrate was amorphous. The average thickness of the PEO deposited films was about 6-10 microns. TiO2 thin films deposited by DC magnetron sputtering were found to be almost amorphous with an average thickness of 650 nm. High resolution TEM analysis showed some areas of crystallinity with a grain size of ~5 nm. Photoelectrocurrent measurements were then performed on all deposited films by a standard single-compartment, three-electrode electrochemical cell. It has been observed that the films deposited by PVD technique have a much higher quality and produce much higher photocurrent comparing to ones of PEO method.

Disciplines

Engineering | Materials Science and Engineering

Comments

Degree granted by The University of Texas at Arlington

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