Self-Filtering Monochromatic Infrared Detectors Based on Bi₂Se₃ (Sb₂Te₃)/Silicon Heterojunctions

This paper focuses on the photoelectric properties of heterostructures formed by surface-modified Si (111) and hexagonal, quintuple-layered selenides (Bi₂Se₃ and Sb₂Te₃). It was shown that H-passivated Si (111) can form robust Schottky junctions with either Bi₂Se₃ or Sb₂Te₃. When back illuminated (i.e., light incident towards the Si side of the junction), both the Bi₂Se₃/Si and Sb₂Te₃/Si junctions exhibited significant photovoltaic response at 1030 nm, which is right within the near-infrared (NIR) light wavelength range. A maximum external quantum efficiency of 14.7% with a detection response time of 2 ms for Bi₂Se₃/Si junction, and of 15.5% with a 0.8 ms response time for the Sb₂Te₃/Si junction, were achieved. Therefore, utilizing Si constituents as high-pass filters, the Bi₂Se₃ (Sb₂Te₃)/Si heterojunctions can serve as monochromatic NIR photodetectors.