Role of oxygen concentration distribution and microstructure in luminescent properties of laser-irradiated silicon

Photoluminescence (PL) of monocrystalline silicon irradiated by femtosecond laser pulses was studied. The visible blue luminescence is observed both from the deionized water and air. The position and shape of emission luminescence peaks in the visible range are same at 330 nm. The PL is confirmed to be not merely induced by the oxygen defects or quantum confinement effects, but is commonly decided by the concentration distribution of SiOx and the depth of the surface microstructure. The PL gets strongest only when depth of the surface microstructure is not deeper and the distribution of the shallow SiOx is more intensive.