Bias Tunable SnS 2 /ReSe 2 Tunneling Photodetector with High Responsivity and Fast Response Speed

2D photodetectors operating in photovoltaic mode exhibit a trade-off between response speed and photoresponsivity. This work presents a phototransistor based on SnS /ReSe heterojunction. Under negative bias, the energy band spike at the heterojunction interface impedes the carrier drifting so that the dark current is as low as 10 A. The tunneling under positive bias significantly reduces the transmission time of photogenerated carriers, which enhances the responsivity and specific detectivity to 32.77 A W and 5.77 × 10 Jones, respectively. Under reverse bias, the enhanced built-in electric field strengthens the rapid separation of photogenerated carriers, which elevates a response speed to 10.5/24.1 µs and a 3 dB bandwidth to 54.8 kHz. The device also exhibits a broad spectral detection capability, extending from the near-ultraviolet to the near-infrared. Furthermore, this work also executed high-quality ASCII communication and high-resolution broadband single-pixel imaging, which demonstrates great promise for incorporation into future broadband optoelectronic systems.