Deposition methods and thermoresistive properties of vanadium oxide and amorphous silicon thin films

Date of Award

2015

Degree Name

M.S. in Electro-Optics

Department

Department of Electro-Optics and Photonics

Advisor/Chair

Advisor: Andrew Sarangan

Abstract

Microbolometer IR imagers consist of an array of thermally sensitive pixels that change resistance as infrared radiation is focused onto the array. Commonly used thermoresisitive materials are amorphous silicon (a-Si) and vanadium oxide (VOx). Despite their use in image sensors, these films are extremely difficult to produce with widely varying process conditions being reported in the literature. Therefore, the goal of this work was to examine the process windows of some of these methods, including novel approaches such as oxygen ion assisted deposition (IAD), aluminum-induced crystallization and glancing angle deposition. Among the thermoresistive materials, vanadium oxide has been widely used in microbolometers due to their excellent thermoresistive properties, relatively fast thermal time constants and high temperature coefficient of resistance (TCR). In our work, we examined different physical vapor deposition methods including: RF reactive sputtering of metallic vanadium to produce vanadium oxide, thermal evaporation of vanadium films and subsequent oxidation, and Oxygen Ion-Assisted Deposition (IAD) of e-beam evaporated vanadium. In addition to VOx, amorphous silicon is also desirable because it can be easily integrated into the CMOS fabrication processes more than VOx. The hydrogenated amorphous silicon produced by PECVD has a high TCR and a relatively high optical absorption coefficient. In addition to PECVD, we used a glancing angle deposition and also examined a novel approach to create polycrystalline silicon from aluminum-induced crystallization.

Keywords

Physical vapor deposition, Thin films Thermal properties, Bolometer Design and construction, Engineering

Rights Statement

Copyright © 2015, author

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