A high-performance near-infrared light photovoltaic detector based on a multilayered PtSe2/Ge heterojunction

Light detection in the near-infrared (NIR) region is of particular importance due to its wide application for both military and civil purposes. In this study, we fabricated high-performance NIR photodetectors by simply transferring a multilayered PtSe2 film onto a Ge wafer to form vertical hybrid heterojunctions. These heterojunctions exhibit an apparent photovoltaic effect under NIR illumination, offering our devices the opportunity to operate without an external power supply. Based on further optoelectronic analysis, it was found that the devices were highly sensitive to the 1300, 1550, 1650 and even 2200 nm NIR illumination with good reproducibility and long-term air stability. Under the 1550 nm irradiation, the NIR photodetectors attained the high responsivity and specific detectivity of 602 mA W-1 and 6.3 x 10(11) Jones, respectively, along with fast response speed of 7.4/16.7 s at zero bias. Due to the excellent photoresponse performance and the simple device geometry, the present self-driven NIR photodetectors are very promising for application in future optoelectronic devices and systems.