Effect of oxygen pressure during the growth of ZnSnO3 epitaxial thin films on LiNbO3 substrates

High-quality ZnSnO3 epitaxial films are grown on LiNbO3(0001) substrates by pulsed laser deposition in an oxygen pressure range of 0.1-10 Pa. The crystalline quality, composition, surface topography, structure, defect formation energy and photovoltaic properties of the epitaxial films are found to be highly sensitive to change in the oxygen pressure by experiments and first-principles density functional theory (DFT). The epitaxial rela-tionship between the film and the substrate is identified as ZnSnO3(0001) || LiNbO3(0001) with ZnSnO3 [2 110] || LiNbO3[2 110]. The film grown atPO2 = 10 Pa has the highest crystal quality, but the photodetector based on the film obtained atPO2 = 0.1 Pa presents the highest responsivity (2.24 A/W at 1 V) and light/dark current ratio (-105 at 1 V) under the 254-nm-light irradiation. Our results indicate that the as-grown ZnSnO3 epitaxial film should be a potential material for fabricating high-performance UV photodetectors.