Suppression of the metal-insulator transition in magnetron sputtered Ti2O3 films

Abstract

We report on the synthesis of titanium suboxide films using a magnetron sputtering setup. The structure of the produced films is characterized using Raman spectroscopy and X-ray diffraction and electrical properties are measured by four-probe method. We demonstrate that depending on the oxidation rate of the growing films it is possible to produce polycrystalline α- TiO, corundum and orthorhombic Ti2O3 or almost amorphous TiO2. We focus on the characterization of the two phases of Ti2O3 and show that their structure and electrical properties significantly differ from earlier results obtained for bulk crystals or epitaxial films. Our corundum-type Ti2O3 films have high electrical conductivity (compared to the bulk) and no metal-insulator phase transition: the material is locked in the metallic state. The conductivity of our orthorhombic Ti2O3 is lower compared to epitaxial films; this phase does not demonstrate any phase transitions as well.