MoS2-HgTe Quantum Dot Hybrid Photodetectors beyond 2 µm

Abstract

Mercury telluride (HgTe) colloidal quantum dots (CQDs) have been developed as promising materials for the short and mid‐wave infrared photodetection applications because of their low cost, solution processing, and size tunable absorption in the short wave and mid‐infrared spectrum. However, the low mobility and poor photogain have limited the responsivity of HgTe CQD‐based photodetectors to only tens of mA W−1. Here, HgTe CQDs are integrated on a TiO2 encapsulated MoS2 transistor channel to form hybrid phototransistors with high responsivity of ≈106 A W−1, the highest reported to date for HgTe QDs. By operating the phototransistor in the depletion regime enabled by the gate modulated current of MoS2, the noise current is significantly suppressed, leading to an experimentally measured specific detectivity D* of ≈1012 Jones at a wavelength of 2 µm. This work demonstrates for the first time the potential of the hybrid 2D/QD detector technology in reaching out to wavelengths beyond 2 µm with compelling sensitivity.