Broadband infrared photodetector based on nanostructured MoSe₂-Si heterojunction extended up to 2.5 μm spectral range

Transition metal dichalcogenides (TMDs) and their heterojunctions are drawing immense research interest for various applications including infrared detection. They are being studied with different semiconductor materials to explore their heterojunction properties. In this regard, we report a MoSe₂/Si heterojunction broadband photodiode which is highly sensitive for a wide spectral range from 405 nm to 2500 nm wavelength with the maximum responsivity of ∼522 mA W^-1 for 1100 nm of incident light. The hydrothermal synthesis approach leads to the imperfect growth of the MoSe₂, creating defects in the lattice, which was confirmed by x-ray photo-spectroscopy. These sub-bandgap defects caused high optical absorption of the SWIR light as observed in the absorption spectra. The speed of the device ranges to 18/10 μs for 10 kHz modulated light. Furthermore, the photodetector has been fully operational even at zero bias voltage, making it a potential contender for self-powered photodetection.