Date of Award

Spring 2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical Engineering

First Advisor

Iyer, Shanti

Abstract

With the growing need for large area display technology and the push for a faster and cheaper alternative to the current amorphous indium gallium zinc oxide (a-IGZO) as the active channel layer for pixel-driven thin film transistors (TFTs) display applications, gallium tin zinc oxide (GSZO) has shown to be a promising candidate due to the similar electronic configuration of Sn4+ and In3+. Post deposition annealing at 450 °C of the films in air was found to lead to a high atomic concentration of Sn4+ in the films as ascertained by x-ray photoelectron spectroscopy, which is one of the prerequisites for improved performance of the device. In this work a systematic and detailed study of GSZO TFTs with the channel annealed at 450°C has been carried out, and different effects have been investigated, including: oxygen flow, deposition contacts, further annealing in different ambients and presence of passivation layer on the TFT performance. The electrical and optical stability of the GSZO TFTs have also been the subject of study. These studies provided a more insight into the role of surface and interface states on the TFT performance and its degradation mechanism under stress. Improved device performance with VON of -3.5 V, ION/IOFF of 108, μFE = 4.36 V-1 s-1, and sub-threshold swing (SS) of 0.38 V/dec has been achieved, which is close to those of industrial standard IGZO TFTs. Thus, this work demonstrates GSZO based TFTs as a promising and viable option to the IGZO TFTs.

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