Due to its superior carrier mobility and high air stability, the emerging two-dimensional (2D) layered bismuth oxyselenide (Bi 2 O 2 Se) nanosheets have attracted extensive attention, showing great potential for applications in the electronic and optoelectronic fields. However, a high mobility easily leads to a high dark current, seriously restricting optoelectronic applications, especially in the field of photodetectors. In this paper, we report a high-quality Van der Waals (vdWs) Bi 2 O 2 Se/Bi 2 Se 3 heterostructure on a fluorophlogopite substrate, exhibiting excellent photodiode characteristics. By means of the effective separation of photogenerated electrons and holes by a junction barrier at the interface, the current on/off ratio is up to about 3 × 10 3 under 532 nm laser illumination with zero bias. In addition, the photodetector not only achieves a fast response speed of 41 ms but also has a broadband photoresponse from 532 to 1450 nm (visible−NIR). Additionally, the responsivity can reach 0.29 A/W, and the external quantum efficiency exceeds 69% when the device operates in the reverse bias condition. The results indicate that the Bi 2 O 2 Se/Bi 2 Se 3 vdWs heterostructure has great potential for self-powered, broadband, and fast photodetection applications.
Abstract2D bismuth oxyselenide (Bi2O2Se) nanosheets have received increasing attention in the field of electronics and optoelectronics due to their high‐mobility, moderate energy bandgap, and air‐stability. However, due to the intrinsic high mobility, the photodetectors based on 2D Bi2O2Se have an inevitable high dark current, leading to high power consumption and limiting its potential application in photodetection. Herein, a novel highly sensitive WS2/Bi2O2Se van der Walls (vdWs) heterostructure with straddling band configuration is assembled on fluorophlogopite substrate. Owing to the effective separation of photogenerated electron–hole pairs and the quantum tunneling effect, the responsivity and external quantum efficiency of the WS2/Bi2O2Se heterostructure are 628 mA W−1 and 147.6% under 532 nm illumination, respectively. The Iphoto/Idark ratio with more than two orders of magnitude can be obtained, and the rise time is ≈33 ms, while the fall time is 38 ms. Furthermore, the heterostructure achieves a broadband photodetection capability from visible to near infrared (532–1450 nm). The results suggest that the WS2/Bi2O2Se vdWs heterostructure possesses a promising potential application prospect in high performance and broadband photodetectors.
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