Effects of hydrogenation on photoluminescence of Si nanoparticles formed by pulsed laser ablation

We report a photoluminescence (PL) study of hydrogenated Si nanoparticles formed by pulsed laser ablation. Two kinds of visible luminescence centered at 480 and 750 nm were observed by varying hydrogen gas pressure. The 480 and 750 nm emissions were obtained from the sample formed in higher- and lower-pressure region, respectively. The PL wavelength did not depend on the particle size. From a comparison of luminescence spectra and surface environment of the particle, the 480 nm emission attributed to defects in native oxide layer and the 750 nm emission appeared as the result of hydrogen passivating interface states at the Si/SiO2. The result indicates that the surface environment plays an important role for PL characteristics of Si nanoparticle.