Optical properties of aluminium oxide thin films prepared at room temperature by off-plane filtered cathodic vacuum arc system

Abstract

An off-plane filtered cathodic vacuum arc (FCVA) system has been developed to deposit large area (up to 8 inch) optical coatings with good uniformity controlled by scanning magnetic field system. With this FCVA system, aluminium oxide thin films were deposited with high deposition rate (1.5-0.5 nm/s) on Si (100) and quartz substrates at room temperature under different oxygen pressures (1×10−2–3.73×10−2 Pa). The evolution of Al 2p core level and oxygen concentration in the films was studied by XPS spectra. In addition to the good uniformity (±2%) in terms of thickness and smooth surface (RMS: approx. 0.1 nm), the as-grown films were amorphous with low stress (less than 0.5 GPa). The variation of deposition rate with oxygen pressure was investigated. Optical properties, such as film transmittance and optical constants of aluminium oxide thin films formed under different oxygen pressures were determined. Film properties demonstrate the potential applications for aluminium oxide thin films in optical coatings and for FCVA technology in deposition of metal oxide optical coatings.