Reconfigurable WSe2 Schottky heterojunctions for logic rectifiers and ultrafast photodetectors

Van der Waals heterojunction-based self-powered photodetectors (SPPDs) based on two-dimensional materials play an important role in the fields of logic optoelectronics and intelligent image sensors. Herein, we fabricated a PtSe2/WSe2/Au asymmetric Schottky photodiode with a bottom-contact structure via mechanical exfoliation and dry transfer. Owing to the merits of gate-tunable Schottky barrier height, avoidance of the Fermi pinning effect of Au/WSe2, high conductivity of semi-metallic PtSe2, and excellent interlayer coupling effect between PtSe2 and WSe2, the diode features polar reconfiguration which induces gate-tunable positive and negative rectifying behavior with a rectification ratio ranging from 10−2 to 104, verifying the potential as a half-wave logic rectifier. In addition, the self-powered device exhibits a maximum photoresponsivity of 316 mA W−1, a Ilight/Idark ratio of 105, a photoelectric conversion efficiency of 4.62%, and a fast response speed. The scanning photocurrent mapping reveals that the photocurrent is primarily distributed at the edge of the Au/WSe2 interface, indicating that it is an asymmetric Schottky photodiode. Finally, a high-resolution visible-light single-pixel imaging measurement is achieved. This study offers a straightforward effective approach for producing high-performance half-wave rectifiers, ultrafast SPPDs, and high-resolution image sensors.