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 Hz1/2 W-1 under blackbody radiation at room temperature, and peak detectivity of up to 1011  cm Hz1/2 W-1 at 77 K. Thereby, this work facilitates the effective design of high-speed and high-performance heterojunction uncooled MWIR photodetectors.