Influence of Various Target to Substrate Distances on the Structural and Optical Properties of Sputtered Gd-Doped ZnO Thin Films

Abstract

The effect of various target to substrate distance on the physical properties of sputtered Gd-doped ZnO thin films were investigated. The thin films with three distances between a target to substrate ranged from 12.0, 13.5 and 15.0 cm were deposited by a dual-target sputtering method. All the thin film properties were characterized using x-ray diffraction, atomic force microscope, energy dispersive x-ray analysis and ultra-violet visible spectrophotometer. The sharp and intense peak of (002) was observed for a sample with the target to substrate distance of 13.5 cm which indicated good crystallinity as compared to other samples. Gd incorporations of 3 at% in ZnO films were further confirmed via the energy dispersive x-ray analysis. AFM images revealed that the surface topology Gd-doped ZnO thin film have a smooth and uniform surface. The transmittance was above 90 % and slightly decrease with the increase of target to substrate distance. The bandgap value was static at 3.14 eV for all the 12.0, 13.5 and 15.0 cm of various target to substrate distances.