Type-II Bi 2 O 2 Se/MoTe 2 van der Waals Heterostructure Photodetectors with High Gate-Modulation Photovoltaic Performance.

In recent years, two-dimensional (2D) nonlayered Bi 2 O 2 Se-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 Bi 2 O 2 Se-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 Bi 2 O 2 Se/2H-MoTe 2 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 ( R ) of 1.24 A·W -1 , and a high specific detectivity ( D *) of 3.73 × 10 11 Jones under 405 nm are achieved. In particular, R , D *, fill factor, and photoelectrical conversion efficiency (PCE) can be enhanced to 4.96 A·W -1 , 3.84 × 10 12 Jones, 0.52, and 7.21% at V g = -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.