Physical structure of light-emitting porous polycrystalline silicon thin films

This paper reports the surface electronic structure of light-emitting porou s polycrystalline silicon (PPS) using X-ray photoelectron spectroscopy (XPS ). We find that the PPS films with strong photoluminescence (PL) effect can only be observed in thin film with tract amount of silicon nanoclusters an d the luminescence can be enhanced remarkably with proper passivation of th e PPS surface, incomplete oxidation of silicon (Si3+ or Si2+) does not lead to visible FL. We further estimate that the avt rage size of silicon nanoc lusters is in the range of 20-30 Angstrom in the sample having PL emission. (C) 1999 Elsevier Science Ltd. All rights reserved.