RF-Sputtered ZnO Thin Films: The Tailoring of Structural, Electrical and Optical Properties

Abstract

ABSTRACTWe report on the influence of radio-frequency magnetron sputtering variables (working pressure and deposition atmosphere) and post-deposition thermal treatment processing upon the structural, optical and electrical properties of c-axis highly textured ZnO thin films. The films’ crystallinity increased progressively with argon pressure for the inert atmosphere experiments and with the oxygen dilution in the working atmosphere (up to 10%) for the reactive atmosphere experiments. The post-deposition annealing treatment at 450°C/1h in air reduced the strain in the ZnO films and enhanced their crystallinity and texturing. The ZnO films had an average transmittance of ∼90% in visible range and an average band-gap of ∼3.4 eV, regardless of the sputtering variables used. The samples prepared at the higher argon pressure (0.45 Pa) had a resistivity with one order of magnitude smaller than the samples prepared at the lower pressures.