High‐Performance Bi₂O₃/SnS–SnO₂/p‐Si Heterojunction Broadband Photodetector with Low Dark Current and Fast Response

Currently, constructing multiheterojunction photodetectors by using reasonable band arrangement between different materials is an effective means to enhance the photodetector's optical response, broaden its working range, and reduce the response time. In this investigation, a novel heterojunction structure of Bi 2 O 3 /SnS–SnO 2 /p‐Si (BSS) is fabricated via a modified two‐step sol–gel spin coating technique. Comparative analysis with the original SnS–SnO 2 and binary Bi 2 O 3 /SnS–SnO 2 (BS) heterojunctions reveals that the ternary heterojunction BSS photodetector demonstrates broad‐spectrum light response and reduced dark current, operating within a wavelength range from 254 to 1200 nm. Under a bias voltage of −5 V and illumination at 780 nm, the device exhibits a photocurrent of 1.42 × 10 −5 A and low dark current of 10 −10 A, yielding an impressive switching ratio of 2.91 × 10 4 . Additionally, the response time of the BSS device is 0.04 s, which is 123 times faster than the SnS–SnO 2 device. Furthermore, under 780 nm illumination,the responsivity R and detection sensitivity of the heterojunction are measured to be 0.14 A W −1 and 1.13 × 10 12 Jones, respectively. These findings underscore that rational band alignment of the BSS ternary heterojunctions is pivotal for their exceptional performance and highlights their potential for advancement as a broadband high‐performance photodetector.