Photoreduction and oxidation of as-deposited microcrystalline indium oxide

Abstract

Indium oxide (InOx) films with a thickness of 100–500 nm were prepared by dc magnetron sputtering onto Corning 7059 glass substrates. The as-deposited films were microcrystalline as revealed by x-ray diffraction analysis. The conductivity of the as-deposited films was of the order of 10−3–10−2 Ω−1 cm−1 and increased up to the order of 101–102 Ω−1 cm−1 by exposure to ultraviolet light hν≥3.5 eV in vacuum. By subsequently exposing the same films to an oxidizing atmosphere they reverted to the insulating state. Photoreduction and oxidation have been shown to change the conductivity properties of one and the same film in a fully reversible manner. In this article, we demonstrate that the large reversible conductivity changes produced by UV photoreduction and oxidation are not limited to amorphous InOx but are equally observed in microcrystalline InOx.