Structure, electrical and optical properties of ZnO and Cu-doped ZnO films prepared by magnetron sputtering at different H2 fluxes

Abstract

Zn1-xCuxO (x = 0 and 0.02) films were prepared by RF magnetron sputtering in H2-containing atmosphere at 150 ?C. Their structure and optical-electrical properties as functions of H2 flux were investigated. With increase of H2 flux, thickness of both films decreases and their surface roughness increases at first and then decreases. Preferred (002) orientation and improved crystallinity of both films were observed in specific interval of H2 fluxes. With increasing H2 flux, the VO content of ZnO and Cu-doped ZnO films decreases at first and then increases and decreases, respectively, but the Zni content in both films increases at first and then decreases. Compared with ZnO films, Cu-doped ZnO films have lower VO and Zni contents, and they maintain thicker film thickness and higher crystallinity at largerH2 fluxes. Both films can obtain low resistivity in appropriateH2 flux ranges, but their resistivity increases significantly after vacuum annealing. With increasing H2 flux, intensity ratio of A1(LO) to E2 high scattering peaks, I(A1(LO))/I(E2 high), tends to increase, and scattering peaks around 135 and 185 cm?1 appear. Compared with ZnO films, Cu-doped ZnO films can obtain lower resistivity, better electrically conductive stability in air, lower I(A1(LO))/I(E2 high) and smaller Eg. High H2 fluxes can cause decrease of TVis of the Cu-doped ZnO films. The influence mechanisms of introducing H2 on microstructure and lattice defects of the films were discussed, and correlation between the optical-electrical properties of the films and the microstructure and lattice defects was analysed.