Visible luminescence from silicon surfaces fabricated by femtosecond laser pulses

The photoluminescence (PL) from microstructured silicon fabricated by femtosecond laser pulses in air was studied. In photoluminescence spectra measurements, the orange PL peak (603 nm) and the red PL band (near 680 nm) were observed even without annealing. The scanning electron microscope images (SEM) revealed that lots of nanoclusters and nanoparticles were deposited on the silicon surface. Fourier transform infrared spectroscopy (FT-IR) and energy dispersive spectroscopy (EDS) indicated that the oxygen element played an important role in the photoluminescence. The results confirmed that the red PL band and the orange PL peaks derived from the recombination of the quantum confinement effect and the suboxides (SiOx), respectively. Meanwhile, The oxygen content determined the orange PL intensity, and the size of nanoparticles decided the quantum confinement effect.