Origin of light emission from silicon nanoparticles

Light emission characteristics from silicon nanoparticles consisting of a crystalline core encased in an amorphous oxide shell are reported. The particles were thermally oxidized to further reduce the silicon core dimensions. Photoluminescence measurements reveal substantial difference in emission intensities and peak wavelengths under low and high excitation levels. The results indicate that at least two mechanisms contribute to the light emission from Si nanoparticles, one associated with quantum size effects, and another possibly related to surface defects.