Applied Surface Science, Vol.330, 449-454, 2015
Role of oxygen concentration distribution and microstructure in luminescent properties of laser-irradiated silicon
We study the photoluminescence (PL) of monocrystalline silicon irradiated by femtosecond laser pulses in different environments (deionized water and air) and energy intensities. The fluorescence spectroscopy measurement results indicate that the visible blue luminescence is observed both from the silicon surfaces ablated in the deionized water and air. The more interesting phenomenon is that the position and shape of the emission luminescence peaks in the visible range are substantially the same at the same excitation wavelength 330 nm. Compared with the granular-like microstructure generated on the silicon surface in air, the smaller and stripe-like microstructure is formed in the deionized water as the field emission scanning electron microscope (FESEM) measures. The results of the energy dispersive spectroscopy (EDS) show that silicon and oxygen is the main elemental composition on laser-induced silicon surfaces, and the oxygen content on the sample surfaces formed in air is nearly four times more than that in the deionized water. The studies confirm that oxygen element plays an important role in PL enhancement. The PL is not merely caused by the oxygen defects or quantum confinement effects, but is commonly decided by the concentration distribution of SiOx (x < 2) and the depth of the surface microstructure. The PL achieves the strongest only when the surface microstructure depth is not too deep and the shallow low oxide SiO, is intensive. (C) 2015 Elsevier B.V. All rights reserved.