Fast Uncooled Mid‐Wavelength Infrared Photodetectors with Heterostructures of van der Waals on Epitaxial HgCdTe

Uncooled infrared photodetectors have evoked widespread interest in basic research and military manufacturing because of their low-cost, compact detection systems. However, existing uncooled infrared photodetectors utilize the photothermoelectric effect of infrared radiation operating at 8-12 µm, with a slow response time in the millisecond range. Hence, the exploration of new uncooled mid-wavelength infrared (MWIR) heterostructures is conducive to the development of ultrafast and high-performance nano-optoelectronics. This study explores a van der Waals heterojunction on epitaxial HgCdTe (vdWs-on-MCT) as an uncooled MWIR photodetector, which achieves fast response as well as high detectivity for spectral blackbody detection. Specifically, the vdWs-on-MCT photodetector has a fast response time of 13 ns (77 MHz), which is approximately an order of magnitude faster than commercial uncooled MCT photovoltaic photodetectors. Importantly, the device exhibits a photoresponsivity of 2.5 A W^-1 , quantum efficiency as high as 85%, peak detectivity of 2 × 10¹⁰ cm Hz^1/2 W^-1 under blackbody radiation at room temperature, and peak detectivity of up to 10¹¹ cm Hz^1/2 W^-1 at 77 K. Thereby, this work facilitates the effective design of high-speed and high-performance heterojunction uncooled MWIR photodetectors.