Bi2O2Se/BP van der Waals heterojunction for high performance broadband photodetector

Broadband photodetector has wide applications in the field of remote sensing, health monitoring and medical imaging. Two-dimensional (2D) materials with narrow bandgaps have shown enormous potential in broadband photodetection. However, the device performance is often restricted by the high dark currents. Herein, we demonstrate a high performance broadband photodetector by constructing Bi2O2Se/BP van der Waals heterojunction. The device exhibits a p-n diode behavior with a current rectification ratio of ∼20. Benifited from the low dark current of the heterojunction and the effective carrier separation, the device achieves the responsivity (R) of ∼ 500 A/W, ∼ 4.3 A/W and ∼ 2.3 A/W at 700 nm, 1310 nm and 1550 nm, respectively. The specific detectivity (D*) is up to ∼ 2.8×10 Jones (700 nm), ∼ 2.4×10 Jones (1310 nm) and ∼ 1.3× 10 Jones (1550 nm). Moreover, the response time is ∼ 9 ms, which is more than 20 times faster than that of individual BP (∼ 190 ms) and Bi2O2Se (∼ 180 ms) devices.