Optical properties of filtered cathodic vacuum arc-deposited zirconium oxide thin films

Zirconium oxide thin films were grown on n-Si(100) and quartz substrates by using an off-plane filtered cathodic vacuum arc without external heating. A Zr cathode was used to obtain the plasma and the deposition rate was varied from 75 to 35 nm min-1 corresponding to various oxygen flow rates. Optical properties of as-deposited films are presented as a function of oxygen flow rate and shown to depend greatly on it. The transmittance and optical band gap (Eg) increase with the oxygen flow rate whereas optical constants decrease. Film optical homogeneity is considerably enhanced and good homogeneity is exhibited for the films deposited at oxygen flow rate above 50 sccm. Structural homogeneity remains throughout the film depth even though the respective film structure changes with the different oxygen flow rates. Bulk-like stoichiometric amorphous zirconium oxide film exhibits high E g (5.0 eV), high transmittance and good optical constants (high refractive index of 2.16 at 550 nm and low extinction coefficient of ∼10-5 at 550 nm) with homogeneous structure.