Material properties of indium oxide films prepared by oxygen ion assisted deposition

Abstract

Transparent conducting In2O3 films were deposited on glass substrates by an oxygen ion assisted deposition. Microstructure, chemical composition, electrical, and optical properties of the deposited films were investigated as a function of arrival ratio and ion energy. At 60 eV oxygen ion bombardment, the microstructure was changed from grain structure to domain structure with increasing the arrival ratio. At 500 eV oxygen ion bombardment, the only grain structure was observed, irrespective of the arrival ratio. The ion assisted films had higher oxygen content than the evaporated film without oxygen ion bombardment because of the enhanced reactivity of oxygen due to ionization. Electrical and optical properties of the ion assisted films were significantly dependent on the change of microstructure and chemical composition with varying the arrival ratio and the ion energy. Compared to the films having the grain structure, the films with the domain structure had larger carrier concentration and mobility due to a low grain boundary density acting as a trap and a reduced grain boundary scattering. The high transmittance (≈89%) in the visible spectral range was obtained in the ion assisted films with the large oxygen content and the small surface roughness.