Light emission from thermally oxidized silicon nanoparticles

Light emission characteristics from silicon nanoparticles consisting of a crystalline core encased in an amorphous oxide shell are presented. The particles were thermally oxidized in the open atmosphere at 800 °C for times from 5 to 160 min in order to decrease the Si core dimensions. Photoluminescence spectra, at low excitation levels, reveal that the light emission shifts to shorter wavelengths as the oxidation time is increased. At high excitation levels, photoluminescence spectra show little or no shift. These results indicate that there are at least two mechanisms involved with light emission from Si nanoparticles, one associated with quantum size effects and another which is independent of size distribution.