Vibrational spectra of defects in silicon: An orbital radii approach.

A phenomenological approach to the stretching mode vibrational frequencies of defects in semiconductors is proposed. A novel quantum scale is defined in terms of the first principles pseudopotential based orbital radius rs and the principal quantum number of the element concerned. A universal linear relationship between the Sanderson electronegativity (SR ) and this quantum scale is established. Next, we show that the stretching mode vibrational frequencies of hydrogen (νSi−H) and chlorine (νSi−Cl) in the silicon network scale linearly with this quantum scale. Predictions and identifications of defect environments around the Si-H and Si-Cl are possible. The assignments of vibrational modes in porous silicon are critically examined. We discuss our proposed scale in the context of Mendeleveyan scales in general, and suggest justifications for it. We believe that our approach can be gainfully extended to the vibrational spectra of other semiconductors. PACS INDEX: 78.30.-j, 78.66.Db, 78.66.Jg Typeset using REVTEX ∗On leave from Science College, Patna-800005,INDIA