H-BN-encapsulated uncooled infrared photodetectors based on tantalum nickel selenide

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 (Ta${}_2$NiSe${}_5$) 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-Ta${}_2$NiSe${}_5$-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 × 10${}^8$ 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 Ta${}_2$NiSe${}_5$ as a promising low-dimensional material for advanced applications in nano-optoelectronic device. (© 2023 Wiley‐VCH GmbH)