Fully Depleted Self-Aligned Heterosandwiched Van Der Waals Photodetectors

Room-temperature-operating highly sensitive mid-wavelength infrared (MWIR) photodetectors are utilized in a large number of important applications, including night vision, communications, and optical radar. Many previous studies have demonstrated uncooled MWIR photodetectors using 2D narrow-bandgap semiconductors. To date, most of these works have utilized atomically thin flakes, simple van der Waals (vdW) heterostructures, or atomically thin p-n junctions as absorbers, which have difficulty in meeting the requirements for state-of-the-art MWIR photodetectors with a blackbody response. Here, a fully depleted self-aligned MoS₂ -BP-MoS₂ vdW heterostructure sandwiched between two electrodes is reported. This new type of photodetector exhibits competitive performance, including a high blackbody peak photoresponsivity up to 0.77 A W^-1 and low noise-equivalent power of 2.0 × 10^-14  W Hz^-1/2 , in the MWIR region. A peak specific detectivity of 8.61 × 10¹⁰  cm Hz^1/2  W^-1 under blackbody radiation is achieved at room temperature in the MWIR region. Importantly, the effective detection range of the device is twice that of state-of-the-art MWIR photodetectors. Furthermore, the device presents an ultrafast response of ≈4 µs both in the visible and short-wavelength infrared bands. These results provide an ideal platform for realizing broadband and highly sensitive room-temperature MWIR photodetectors.