Nanolayered Black Arsenic–Silicon Lateral Heterojunction Photodetector for Visible to Mid-Infrared Wavelengths

Room temperature broadband photoresponse through a single device is still the precedency of the scientific community. Many techniques, such as extensive nanoscale patterning, heterostructure patterning/growth, and field-induced band gap tuning, have been employed in this direction. However, the room temperature photoresponse of existing photodetectors is limited in a single region of the electromagnetic spectrum. We report room temperature broadband photoresponse from the visible to mid-infrared (MIR) region in a nanolayered black arsenic–silicon (bAs–Si) lateral heterojunction-based photodetector. Such a broad spectral range has been facilitated because of the suitable intrinsic band gap of bAs and of Si. This photodetector is fabricated using the mechanical exfoliation of bAs on the silicon-on-insulator (SOI) substrate. The fabricated device shows high photoresponsivities, in the visible to MIR (405 nm to 4 μm) region, which stems from the high absorptivity of bAs and good optical coupling capability of the SOI substrate. The maximum photoresponsivities are obtained as 72.15, 930.49, and 75.2 A/W for the wavelengths 785 nm, 1.05, and 3 μm, respectively. The corresponding maximum detectivities are 3.2 × 109, 4.17 × 1010, and 3.37 × 109 Jones, respectively. This photodetector is capable of sensing a weak optical signal in terms of noise equivalent power from pico to femto W/Hz1/2. Along with this, it has also been observed that this photodetector is slightly sensitive to the polarized incident radiation owing to the anisotropic crystal structure of bAs. Therefore, we envisage the integration of bAs with silicon to offer an enforceable pathway toward the realization of SOI technology for a wide range, including MIR, of optoelectronics.