Room Temperature Single Photon Detection at 1550 nm Using van der Waals Heterojunction

Abstract Single‐photon detectors (SPDs) are crucial in applications ranging from space, biological imaging to quantum communication and information processing. The SPDs that operate at room temperature are of particular interest to broader application space as the energy overhead introduced by cryogenic cooling can be avoided. Although silicon‐based single photon avalanche diodes (SPADs) are well‐matured and operate at room temperature, the bandgap limitation restricts their operation at telecommunication wavelength (1550 nm) and beyond. InGaAs‐based SPADs, on the other hand, are sensitive to 1550 nm photons but suffer from relatively lower efficiency, high dark count rate, afterpulsing probability, and pose hazards to the environment from the fabrication process. In this work, the properties of nanomaterials that can be leveraged to address these challenges are demonstrated and a room‐temperature single‐photon detector capable of operating at 1550 nm is realized. This is achieved by coupling a low bandgap (≈ 350 meV) absorber (black phosphorus) to a sensitive van der Waals probe that is capable of detecting discrete electron fluctuation. The device is optimized for operation at 1550 nm and demonstrates an overall quantum efficiency of 21.4% (estimated as 42.8% for polarized light), and a minimum dark count of ≈ 720 Hz at room temperature.