Broadband photodetector based on vapor-deposited selenium self-supporting films

As a high-quality p-type semiconductor, Selenium (Se) has become an important potential candidate for photoelectric devices due to its high photoconductivity, non-linear optical response, and large piezoelectricity. However, the intrinsic Se has a wide bandgap (about 1.77 eV), so it is usually used for photodetection in the visible region. In this work, the Se self-supporting films have been successfully fabricated by an improved physical vapor deposition (PVD) method, and a metal-semiconductor-Metal (MSM) photodetector based on the Se self-supporting films has been designed for the first time. The photodetector shows broadband photoresponse from visible light to near-infrared (450–1550 nm), which is consistent with the experimental absorption spectrum of the obtained film. Besides, photodetection results indicate that the device exhibits a fast response speed (Tr = 4.5 ms, Td = 63.8 ms) with perfect responsivity (8.1 μA/W) and detectivity (1.3 × 105) under 3 V bias voltage and 450 nm (0.971 mW) light irradiation. The research of this paper will further enrich the application and development of traditional Se semiconductors in the field of optoelectronics.