Effects of O2/Ar ratio and substrate temperature on the structure and optical properties of Cu2O thin films deposited by pulse magnetron sputtering

Cuprous oxide (Cu2O) thin films were prepared on quartz glass substrates by pulsed magnetron sputtering from a metallic copper target in Ar and O2 mixture gas. Effects of O2/Ar ratio and substrate temperature on the crystalline structure, surface morphology and optical properties of Cu2O thin films were investigated. The results showed that at an O2/Ar flow ratio of 30:80, the thin films deposited at room temperature (RT) and 100°C were single-phase Cu2O with preferred orientation. The surfaces of the thin films consist of densely spherical grains. Root mean square (RMS) roughness of the thin films increases as the substrate temperature increasing. Moreover, in the wavelength range of 300-650 nm, the thin films have a strong absorption in the UV region but a relatively weak absorption in the VIS region. Optical density of the thin films increases and optical band gap (Eg) of the thin films decreases as the substrate temperature increasing.