Growth behavior and optical properties of N-doped Cu2O films

N-doped Cu₂O films are deposited by sputtering a CuO target in the mixture of Ar and N₂. The structures zand optical properties have been studied for the films deposited at different temperatures. It is found that N-doping can suppress the formation of CuO phase in the films. The films are highly (100) textured at low temperatures and gradually change to be highly (111) textured at the temperature of 500 °C. With the analysis of (111) and (100) grain sizes, the surface free energy and grain size of critical nuclei are suggested to dominate the film texture. The analysis of the atomic force microscopy shows that the film growth can be attributed to the surface-diffusion-dominated growth. The forbidden rule of band gap transition is found disabled in the N-doped Cu₂O films, which can be attributed to the occupation of 2p electrons of nitrogen at the top of valence band. The optical band gap energy is determined to be 2.52 ± 0.03 eV for the films deposited at different temperatures.