Effects of deposition and annealing temperatures on the electrical and optical properties of Ag2O and Cu2O–Ag2O thin films

Abstract

Ag 2 O and Ag2O–Cu2O films were deposited on glass substrates by magnetron sputtering of Ag and Cu targets at various substrate temperatures. After deposition, some of these films were annealed using a rapid thermal annealing system, with the variation of temperature. An UV-VIS-NIR photometer and a Hall measurement system were used to characterize the optical and electrical properties of these films. On annealing, Ag2O (hexagonal) phase would slowly change to Ag+Ag2O (cubic) phases when the annealing temperature is greater than 200 °C. When the annealing temperature was higher than 450 °C, the Ag2O phase would transform into a metallic Ag phase completely. Accordingly, the band gap of these films will change, along with the optical and electrical properties. In the study of Ag2O–Cu2O films, it is found that these two-phase composite films could exist obviously when deposited at room temperature. The photoinduced current of these composite films could be increased significantly, compared with that of a single Cu2O phase. This is most likely due to that a large band gap semiconductor (Cu2O) is coupled with a small band gap semiconductor (Ag2O).