Preparation of Transparent Conducting ZnO Thin Films Prepared by Laser Ablation Method Using Split Target

Abstract

Thin films of ZnO doped with Al₂O₃, Ga₂O₃, In₂O₃, SnO₂, ITO, Ag₂O and CuO have been deposited on glass substrates by a pulsed laser deposition technique using an ArF laser (λ=193nm). The lowest resistivity was obtained for films deposited from the target with 2wt% Al₂O₃ (AZO(2wt%)); the resistivity of 1.43×10^-4Ω•cm was obtained at a substrate temperature of 300°C. On the other hand, there were minute irregularities on the surfaces of ZnO films doped with 4-7wt% Ga₂O₃ (GZO(4-7wt%)). Therefore, to obtain ZnO films with low resistivity and surface flatness, the laminated films were fabricated from the split target consisting of AZO (2wt%)and GZO (4-7wt%), It was found that (1) the lowest resistivity of 1.82×10-4Ω•cm and the lowest sheet resistance of 4Ω/sq were obtained for the 400nm thick film with four layers, (2) optical transmittance above 90% was obtained in the visible region of the spectrum and (3) there were minute irregularities (average roughness 0.56nm) on the surface of the films.