Modification of the optical properties of ZnO thin films by proton implantation

Optical properties of proton-implanted ZnO thin film prepared by radio-frequency (rf) magneton sputtering have been studied, the optical constants being obtained from the reflectance measurements by employing Cauchy–Urbach model. Increase in the ordinary refractive index after proton implantation was explained by that in the polarizability. Besides, a slight increase in the optical band gap by proton implantation was identified and discussed in terms of the hydrogen shallow donors introduced by the proton implantation.