Type-II BiOSe/MoTe van der Waals Heterostructure Photodetectors with High Gate-Modulation Photovoltaic Performance.

In recent years, two-dimensional (2D) nonlayered BiOSe-based electronics and optoelectronics have drawn enormous attention owing to their high electron mobility, facile synthetic process, stability to the atmosphere, and moderate narrow band gaps. However, 2D BiOSe-based photodetectors typically present large dark current, relatively slow response speed, and persistent photoconductivity effect, limiting further improvement in fast-response imaging sensors and low-consumption broadband detection. Herein, a BiOSe/2H-MoTe van der Waals (vdWs) heterostructure obtained from the chemical vapor deposition (CVD) approach and vertical stacking is reported. The proposed type-II staggered band alignment desirable for suppression of dark current and separation of photoinduced carriers is confirmed by density functional theory (DFT) calculations, accompanied by strong interlayer coupling and efficient built-in potential at the junction. Consequently, a stable visible (405 nm) to near-infrared (1310 nm) response capability, a self-driven prominent responsivity () of 1.24 A·W, and a high specific detectivity (*) of 3.73 × 10 Jones under 405 nm are achieved. In particular, , *, fill factor, and photoelectrical conversion efficiency (PCE) can be enhanced to 4.96 A·W, 3.84 × 10 Jones, 0.52, and 7.21% at = -60 V through a large band offset originated from the n-p junction. It is suggested that the present vdWs heterostructure is a promising candidate for logical integrated circuits, image sensors, and low-power consumption detection.