Construction\nof Bi₂O₂Se/Bi₂Se₃ Van\nDer Waals Heterostructures for Self-Powered\nand Broadband Photodetectors

Abstract

Due to its superior carrier mobility\nand high air stability, the\nemerging two-dimensional (2D) layered bismuth oxyselenide (Bi₂O₂Se) nanosheets have attracted extensive attention,\nshowing great potential for applications in the electronic and optoelectronic\nfields. However, a high mobility easily leads to a high dark current,\nseriously restricting optoelectronic applications, especially in the\nfield of photodetectors. In this paper, we report a high-quality Van\nder Waals (vdWs) Bi₂O₂Se/Bi₂Se₃ heterostructure on a fluorophlogopite substrate, exhibiting\nexcellent photodiode characteristics. By means of the effective separation\nof photogenerated electrons and holes by a junction barrier at the\ninterface, the current on/off ratio is up to about 3 × 10³ under 532 nm laser illumination with zero bias. In addition,\nthe photodetector not only achieves a fast response speed of 41 ms\nbut also has a broadband photoresponse from 532 to 1450 nm (visible–NIR).\nAdditionally, the responsivity can reach 0.29 A/W, and the external\nquantum efficiency exceeds 69% when the device operates in the reverse\nbias condition. The results indicate that the Bi₂O₂Se/Bi₂Se₃ vdWs heterostructure has great\npotential for self-powered, broadband, and fast photodetection applications.