Bi₂Se₃/n-Si Schottky Junctions for Near-Infrared Photodetectors

Bi₂Se₃ thin films with different thicknesses are deposited on prepatterned n-Si substrates by the vapor-solid deposition method, demonstrating photodetector performances in the visible and near-infrared range up to the telecommunication wavelength 1550 nm and showing response times as low as 126 ns. The current voltage characteristics measured in the temperature range 77-300 K indicate the formation of Schottky junctions at the interface between the two materials. The nature of the junctions is discussed considering the effect of disorder at the interface induced by the Bi₂Se₃ film granularity. The temperature dependence of the ideality factors and the Schottky barrier heights is consistent with a thermionic field effect mechanism governing the electron motion through the interface, which is responsible for the fast response of the photodetectors.