Electrical properties of vanadium oxide thin films for bolometer applications: processed by pulse dc sputtering

Abstract

Vanadium oxide (VOx) thin films were deposited on thermally grown silicon oxide substrates using a pure vanadium target in a pulsed dc sputtering technique. Film microstructure, electrical resistivity, temperature coefficient of resistance (TCR) and activation energy were studied as a function of the oxygen partial pressure (pO2) and growth temperatures. The mixed valence VOx thin films deposited at various substrate temperatures between 40 and 300 °C exhibited columnar grain structure even though the samples were found to be x-ray amorphous. The TCR and activation energies of the films increased from 0.4% (K−1) to 2.4% (K−1) and 0.04 eV to 0.28 eV, respectively, by controlling the pO2 content between depositions. The charge carrier transport in the VOx thin films was found to exhibit conventional and inverse Meyer–Neldel compensation mechanisms depending on the growth conditions.