Spectroscopy of electroreflection, the electron band structure, and the mechanism of visible photoluminescence of anisotropically etched silicon

We present the results of studies of electroreflection in the 1.1–4.4 eV spectral range, of electron Auger spectroscopy, and of electron diffraction involving the photoluminescent Si-SiO₂ system prepared via anisotropic chemical etching of the Si(100) surface. These results are explained on the basis of a four-layer model of the band structure and energy transition diagram for a system with a quantum well at the silicon surface, surface electron states at the boundary, and a gradient of the band potential in the transition layer. We find that light-emitting silicon remains an indirect-gap semiconductor and that the visible photoluminescence is due to direct recombinations of the light-excited electrons and holes in the quantum well at the center of the Brillouin zone with the participation of the band of deep localized states, which is due to the presence of oxygen at the silicon surface. Zh. éksp. Teor. Fiz. 116, 1750–1761 (November 1999)