High-performance DUV-visible dual-band photodetector enabled by β-Ga2O3/Au/Cs2AgBiBr6 heterojunction with sandwich architecture

High sensitivity and fast response dual-band photodetectors (PDs) covering the deep-ultraviolet (DUV) to visible spectrum are highly desired for industrial and scientific applications. Herein, a sandwich-architecture PD covering the range from DUV to visible was prepared by stacking a β -Ga 2 O 3 DUV absorbing layer, interdigitated Au electrodes, and a Cs 2 AgBiBr 6 (CABB) visible absorbing layer. At 5 V bias voltage, the sandwich-architecture PD achieves responsivities of 37.74 mA/W at 240 nm and 0.07 mA/W at 450 nm with microsecond response time, respectively, which is superior to the PDs using monolayer β -Ga 2 O 3 or CABB. Furthermore, it demonstrates self-powered dual-band detection capability with maximum responsivity of 8.13 mA/W. Enhanced performance arises from two synergistic mechanisms: a vertical built-in electric field at the β -Ga 2 O 3 /CABB interface spatially separates photogenerated carriers, while a higher hole mobility in CABB facilitates the charge collection under a lateral bias field between Au electrodes. Importantly, the β -Ga 2 O 3 /Au/CABB PD demonstrates high-resolution images under 240 nm and 450 nm illumination. This work provides a route for developing high-performance DUV-visible dual-band photodetectors, highlighting their potential for advanced multispectral imaging applications.