High-performance broadband WO3−x/Bi2O2Se photodetectors based on plasmon-induced hot-electron injection

Two-dimensional (2D) Bi2O2Se has emerged as a promising candidate for broadband photodetection, owing to its superior carrier mobility, outstanding air-stability, and suitable bandgap. However, Bi2O2Se photodetectors suffer limited sensitivity at a near-infrared region due to the relatively weak light absorption at this band. Here, it is demonstrated that coupling with plasmonic nanostructures can effectively improve the performance of Bi2O2Se photodetectors at a broad spectral range of 532–1550 nm. By virtue of plasmon-induced hot-electron injection and the improved light absorption, the WO3−x/Bi2O2Se hybrid photodetector exhibits a high responsivity of ∼1.7 × 106 A/W at 700 nm, and ∼48 A/W at a communication O-band of 1310 nm, which is nearly one order of magnitude higher than that of an intrinsic Bi2O2Se device. Moreover, profited by ultrafast hot electron transfer and the avoided defect trapping, the device maintains a high-speed photoresponse (rise time ∼326 ns, decay time ∼47 μs). Our results show that 2D materials coupled with plasmonic nanostructures is a promising architecture for developing state-of-the-art broadband photodetection.