Tuning of refractive index in Al-doped ZnO films by rf-sputtering using oblique angle deposition

Abstract

Al-doped ZnO thin films were grown by rf-sputtering using the oblique angle deposition technique. The films are formed by tilted dense nanocolumns according to the substrate inclination during the growth. The film refractive index changed 16% due to the film nanocolumn tilt from 0° to 13.5°, which corresponded to substrate inclination from 0° to 75°, respectively. Band gap energy was found to diminish, which was associated to local redistribution of Al concentration x in the Al x Zn 1− x O solid solution around the x ≅ 0.02 average.