High‐Sensitive Uncooled Mid‐Wave Infrared Photodetector Based on PtSe₂/MoTe₂ Heterojunction with Fast Speed

Abstract Mid‐wave infrared (MWIR) sensing technology provides tremendous support for cutting‐edge applications in autonomous navigation, quantum information, and optical telecommunications. Recent researchers have reported substantial advancements in the MWIR photodetection based on 2D topological semimetal platinum selenide (PtSe₂). However, its application prospect has been constrained by limited sensitivity and sluggish response speed. Herein, an uncooled MWIR photodetector integrating PtSe₂ with MoTe₂ is reported, which features high responsivity (R) of 8.4–2.5 A W⁻¹ and specific detectivity (D*) of 4.5 × 10⁹–1.3 × 10⁹ cm Hz^1/2W⁻¹ from 2.75 to 4.25 µm. At 10.6 µm wavelength, it is still able to showcase a decent R of 0.12 A W⁻¹. Notably, the photodetector achieves the brilliant photoresponse speed of 3–5 µs from visible to near‐infrared (NIR) spectral ranges with a competitive 3 dB frequency of 0.13 MHz. Meanwhile, a promising fast response speed of 560 µs is demonstrated at 4050 nm in MWIR range, which unveils its conspicuous ability to track ultrafast and broadband light signals. It might be attributed to the high carrier mobility and strong built‐in electric field at the PtSe₂/MoTe₂ interface. This research can provide a viable pathway for next‐generation room‐temperature MWIR photodetectors with high sensitivity and fast response speed.