Thickness dependence of electrical properties in thin films of undoped indium oxide prepared by ion-beam sputtering

Abstract

Preparation and electrical characterization of undoped indium oxide films were examined as a function of thickness and annealing. Thin films ranging from 1.1 to 113 nm thickness were deposited on glass substrates by ion-beam sputtering. Low-angle X-ray diffraction analysis in multi-layered films showed the possibility that physically continuous and almost flat films were formed even in the thinnest 1.1 nm films. Room temperature resistivity of as-deposited films decreased sharply by more than five orders of magnitude as the thickness increased from 1.1 to 5.2 nm. The 2.4 nm thick films, in its as-deposited state, showed a gradual resistivity modulation with the change of atmosphere between air and argon gas at room temperature. Annealing at 300° C for 5 h in air increased the resistivity drastically; the room temperature resistivity of 24.3 nm thick films changed from 2.2×10−3 Ω cm (as-deposited) to higher than ∼ 105 Ω cm (annealed).