Amorphous In-O thin films with a thickness of ∼0.1 μm were produced by thermal evaporation of indium oxide powder in a vacuum of 10-5-5 × 10-4 Torr onto glass substrates at room temperature. The films had conductivities of either σ0 = 10-3-10-2 (Ωcm)-1 or 0.1-1 (Ω cm)-1. An electric field of 6 × 102-3 × 104 V/m with its consequent transverse current injection (TCI) was applied parallel to the films for 15-400 min in vacuum after deposition, and the conductivity of films was measured as a function of the time for different applied fields. The current injection increased the film conductivity by a factor of 4-6 for the films with the lower σ0 and by a factor of 2-3 for the films with higher σ0. Subsequent TCI in air restored the previous conductivity of the high σ0 films, while subsequent TCI in helium or nitrogen had no effect. The as-deposited films are suspected to consist of high conductivity islets in a low conductivity matrix. The conductivity increase is explained by TCI induced outgassing of O2, leading to an increased carrier concentration at the cathodic extremity of the high conductivity regions, which decreases the distance between high conductivity regions and ultimately connects them together.
- Amorphous materials
- Electrical properties and measurements
- Indium oxide