Effects of Ag contents and deposition temperatures on the electrical and optical behaviors of Ag-doped Cu₂O thin films

Cu₂O-Ag thin films were co-deposited by reactive sputtering on glass substrates. During deposition, Ag contents and deposited temperatures were varied. After deposition, a UV-VIS-NIR photometer and a Hall measurement system were used to characterize the optical and electrical properties of these films. The results showed that the Cu₂O-Ag thin films had a decreased optical transmittance with the increase of Ag contents. The resistivity was also decreased, which is most likely due to the formation of Ag phase. Through the measurement of photo-induced conductivity, it was found that, when Ag concentration was at 4 at.%, the film had the highest increase in conductivity under light irradiation. This is due to the co-existence of Ag₂O and Cu₂O. However, when deposited at a temperature higher than room temperature, the photo-induced conductivity of this film became less obvious, apparently due to the dissociation of Ag₂O. The results of Photoluminescence (PL) measurement confirmed that the Cu₂O-Ag(4 at.%) sample might produce more electron-hole pairs than other samples, which caused the increase of conductivity.