Optoelectronic properties of black silicon fabricated by femtosecond laser in ambient air: exploring a large parameter space.

We study the surface morphology, optical absorption (400-1100 nm), and carrier lifetime of black silicon fabricated by femtosecond (fs) laser in air. We explore a large laser parameter space, for which we adopt a single parameter ξ to describe the cumulative fluence delivered to the sample. We also study the laser-oxidized surface layer by measuring its photoluminescence spectra and comparing its effect on the aforementioned properties. Our study in a broad range of ξ is instructive in choosing laser parameters when targeting different applications.