PbSe/WTe2 Schottky Heterojunction for Low-Noise Mid-Infrared Detection.

Room-temperature midwave infrared (MWIR) detection is crucial for applications such as gas sensing, thermal imaging, and optical communications. However, conventional narrow-band gap semiconductors (such as HgCdTe, InAsSb, and PbSe) suffer from high dark current, leading to significant noise at room temperature. To address this challenge, we propose a hybrid-dimensional PbSe/WTe2 van der Waals heterostructure. The formed Schottky barrier effectively modulates carrier transport through the built-in electric field, resulting in significantly suppressed dark current density (as low as 6.9 × 10-5 A·cm-2) and noise current (8.3 × 10-13 A Hz-1/2). The dark current is reduced by approximately 1 order of magnitude compared to that of pure PbSe devices. Further, the device demonstrates a broad spectral response range from 808 to 4000 nm, with a peak responsivity of 0.75 A/W and specific detectivity of 4.81 × 109 cm Hz1/2 W-1 at 2600 nm, which are comparable with commercial MWIR detectors. Finally, we demonstrate a room-temperature clear blackbody and thermal target imaging by PbSe/WTe2 heterojunction, providing an effective pathway for low-noise room-temperature MWIR detectors.