Enhancing infrared photodiode performance by femtosecond laser hyperdoping

As one of the most abundant elements in the earth’s crust, semiconductor silicon has become the core materials of microelectronics and optoelectronics. Silicon-based infrared photodetector can overcome shortcomings of traditional infrared materials in terms of manufacturing cost, environmental friendliness, and compatibility with CMOS technology. However, the band structure of silicon limits its application in infrared photodetection, which is of great significance for silicon-based optoelectronic integrations. Ultrafast pulsed laser hyperdoping can extend the absorption to infrared wavelengths below the bandgap of silicon. In this paper, using femtosecond laser irradiation process, we fabricated inert argon-hyperdoped black silicon, whose absorption wavelength has been extended to 2500 nm. The combination of hyperdoping, laser ablation, and geometric microstructures enhances sub-bandgap absorption of argon-hyperdoped black silicon even though after thermal annealing. The argon-hyperdoped silicon photodiodes are fabricated based on metal-black silicon ( n ⁺ )-silicon ( n ) double junctions and the photodetector shows favorable photo-response to 1310 nm infrared light under both forward and reverse bias. The inert argon-hyperdoped black silicon, with lower ionized impurity scattering, shows a potential application in infrared photodetection.