Comparison of Dopant Incorporation and Near-Infrared Photoresponse for Se-Doped Silicon Fabricated by fs Laser and ps Laser Irradiation

Abstract

Se-doped silicon films were fabricated by femtosecond (fs) laser and picosecond (ps) laser irradiating Si–Se bilayer film-coated silicon. The surface morphology, impurity distribution, crystal phase, and near-infrared photocurrent response of fs-laser-processed and ps-laser-processed Si are compared. With the same number of laser pulse irradiation, fs laser induces quasi-ordered micron-size columnar structures with some deeper gullies, and ps laser induces irregular nanoscale spherical particles with some cavities. Compared with the fs-laser-produced Se-doped layer, ps laser irradiation produces a Se-doped layer with better crystallinity and higher doping concentration, resulting in a higher photocurrent response for picosecond laser-processed Si in the near-infrared band. The changes brought about by ps laser processing facilitate the application of ultrafast laser-processed chalcogen-doped silicon for silicon-based integrated circuits.