Sub-bandgap absorption and photo-response of molybdenum heavily doped black silicon fabricated by a femtosecond laser

摘要

Molybdenum (Mo)-doped black silicon (Si) is obtained. by using femtosecond. laser irradiation. The concentration of Mo atoms at the depth from 10 to 200 nm has exceeded 10(19) cm(-3). In contrast, the carrier concentration in the Mo-doped layer is lower than 10(15) cm(-3). The surface morphologies with ripple and conical spike microstructures are formed by changing the pulsed laser fluences. The Modoped Si samples exhibit a sub-bandgap (1100 similar to 2500 nm) absorptance of more than 60% at a wavelength of 1310 nm. A Mo-doped Si photodetector is made, and the responsivity of the device for 1310 nm is up to 76 mA/W at a -10 V bias. (C) 2021 Optical Society of America