Comparative study on structural, morphological and optical properties of Zn₂SnO₄ thin films prepared by r.f. sputtering using Zn and Sn metal targets and ZnO–SnO₂ ceramic target

Highlights: • ZTO thin films deposition by two different approaches by sputtering are presented. • Morphological, structural and optical properties are reported. • Transmittance higher than 90% was obtained for the ZTO thin film. • ZTO thin films were found to be suitable for optical and electronic applications. - Abstract: In this paper, Zinc Tin Oxide (ZTO) thin films have been deposited both from a ceramic ZnO–SnO₂ target, and from Zn and Sn metal targets. In the case of the metal layers different thermal treatments were performed to oxidize the deposited Zn and Sn layers and thus to form the desired mixed oxide. In view of future industrial applications, some comparative studies between the approached depositions have been performed. In particular, the influence of thickness and temperature on the structural, morphological and optical properties of the ZTO thin films were investigated by SEM and AFM analyses, revealing smooth and homogeneous surfaces. The optical properties of the as-obtained ZTO thin films in the UV–vis range were investigated as well. Although the best value in terms of transmittance was obtained in the case of oxidized metal films (i.e. 96% vs. 93% for layers grown from a ceramic target), structural and morphological investigations indicated the deposition from ceramic target as the optimal choice to obtain high quality ZTO thin films. Thereby, the results presented in this work confirm both the potential of ZTO as TCO material and the matching of ZTO thin films with the requirements for high quality optical and electronic applications