Optical constants of hydrogenated zinc oxide thin films

Zinc oxide thin films were deposited via radio frequency magnetron sputtering. Hydrogenation of the films was achieved by annealing them at 400 °C under a hydrogen flow rate of 100 sccm. The influence of annealing on the structural, morphological, and optical properties of the films were investigated. X-ray diffraction indicated that the films were polycrystalline and that their crystallinity improved upon annealing. Atomic force microscopy revealed the columnar structure of the films and indicated that the surface roughness increased with annealing. The optical constants of the films were derived from spectrophotometric measurements. The optical properties were improved upon annealing, as revealed by the increase of the refractive index, decrease of the extinction coefficient, and the widening of the band gap.