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Document Type

Thesis - University Access Only

Award Date

2013

Degree Name

Master of Science (MS)

Department / School

Electrical Engineering and Computer Science

First Advisor

Qi Hua Fan

Abstract

Indium tin oxide is a wide band gap degenerate semiconductor and is the most widely used material for transparent conductive films due to its good surface morphology, high conductivity and transparency in the visible region. Indium tin oxide films have been employed in many optoelectronic devices as the transparent electrodes. A variety of deposition methods have been used for depositing indium tin oxide films but RF sputtering is widely used for high quality films. The growth parameters such as power density, gas flow rate, oxygen concentration and the substrate temperature strongly affect film properties. There are reports of process parameter effects on indium tin oxide films, however, grain growth behavior, RMS roughness, optical and electrical properties versus RF power, oxygen concentration and the annealing temperature is not clear. In this study, indium tin oxide films were deposited with RF sputtering using various process parameters such as power, substrate temperature and the oxygen concentration. The films deposited at either low power (25 W) or high power (100 W) possessed higher surface roughness and sheet resistance, while films deposited at medium power (50 W) had low roughness and sheet resistance. Indium tin oxide films deposited in pure argon had increased roughness and transmittance with the substrate temperatures changing from 25 °C to 220 °C. However, in 99% argon and 1% oxygen environment, the films roughness and transmittance did not increase once the substrate temperature was higher than 150 °C. A low-temperature sputtering deposition combined with post high-temperature annealing produced smooth ITO films with high transmittance and conductivity. This new process overcomes the drawbacks of conventional hightemperature and low-temperature processes of ITO films, which have either rough surface due to large grain growth or low conductivity due to poor crystallinity, respectively. Future work can include optimization of surface roughness and optoelectronic properties of ITO films with varying deposition pressure, substrate target distance, oxygen and argon gas concentration and the study of annealing behavior of indium tin oxide films in oxygen environment.

Library of Congress Subject Headings

Indium.
Thin films.
Stannic oxide.
Photovoltaic power generation.

Description

Includes bibliographical references (pages 71-84).

Format

application/pdf

Number of Pages

96

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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