Study of the structure and optical properties of nanocrystalline zirconium oxide thin films deposited at low temperatures

Zirconium oxide thin films are deposited at low temperatures (lower than 350°C) using a filtered cathodic vacuum arc. Film structure, surface morphology and optical properties are systematically investigated. The results show the dependence of the properties on substrate temperature. Film structure develops from amorphous to polycrystalline at 150°C. Further increasing the temperature to 230°C leads to the preferred orientation along [-111] and [-221] directions, and at 330°C along only one observed preferred [-111] direction. In addition, crystal size in all the crystallized films is within 15 nm. The increase of substrate temperature results in an increase of surface roughness from room temperature to 230°C, but to a slight decrease at 330°C. The variations in optical properties, such as optical constants and E _g, with substrate temperature are correlated to the changes in film microstructure.