H‐BN‐Encapsulated Uncooled Infrared Photodetectors Based on Tantalum Nickel Selenide

Abstract Uncooled broadband spectrum detection, spanning from visible to mid‐wave‐infrared regions, offers immense potential for applications in environmental monitoring, optical telecommunications, and radar systems. While leveraging proven technologies, conventional mid‐wave‐infrared photodetectors are encumbered by high dark currents and the necessity for cryogenic cooling. Correspondingly, innovative low‐dimensional materials like black phosphorus manifest weak photoresponse and instability. Here, tantalum nickel selenide (Ta₂NiSe₅) infrared photodetectors with an operational wavelength range from 520 nm to 4.6 µm, utilizing a hexagonal boron nitride (h‐BN) encapsulation technique are introduced. The h‐BN encapsulated metal‐Ta₂NiSe₅‐metal photodetector demonstrates a responsivity of 0.86 A W⁻¹, a noise equivalent power of 1.8 × 10⁻¹¹ W Hz^−1/2, and a peak detectivity of 8.75 × 10⁸ cm Hz^1/2 W⁻¹ at 4.6 µm under ambient conditions. Multifaceted mechanisms of photocurrent generation in the novel device prototype subject are scrutinized to varying wavelengths of radiation, by characterizing the temporal‐, bias‐, power‐, and temperature‐dependent photoresponse. Moreover, the photopolarization dependence is delved and concealed‐target imaging is demonstrated, which exhibits polarization angle sensitivity and high‐fidelity imaging across the visible, short‐wave, and mid‐wave‐infrared bands. The observations, which reveal versatile detection modalities, propose Ta₂NiSe₅ as a promising low‐dimensional material for advanced applications in nano‐optoelectronic device.