Influence of Working Pressure on the Structural, Optical and Electrical Properties of Cr-Doped ZnO Thin Films

Abstract

In this work, Cr-doped ZnO thin films with the hexagonal wurtzite structure and c-axis preferred orientation are prepared with the radio frequency magnetron sputtering technique. The variation of working pressure, from 1.3 Pa to 1.9 Pa, produces variations in the structural, optical and electrical properties of the films. X-ray diffraction results indicate that the intensity of the (002) peak in the films first increases, and then decreases, with an increase in the working pressure. Cr-doped ZnO thin films deposited at 1.5 Pa have perfect optical and electrical properties, a maximal crystal size of 13.43 nm, a transmittance of 85.40%, a minimal dislocation density of 5.544 × 1015 lines m−2, a quality factor of 7.43 × 104 S cm−1, a small residual stress of −0.135 GPa and a low resistivity of 1.15 × 10−3 Ω cm. The band gaps of the films increase with an increase in the working pressure. The results show that the working pressure influences the structural, optical and electrical properties of Cr-doped ZnO thin films.