VIBRATIONAL-SPECTRA OF DEFECTS IN SILICON - AN ORBITAL RADII APPROACH

A phenomenological approach to the stretching mode vibrational frequen cies of defects in semiconductors is proposed. A quantum scale is defi ned in terms of the first principles pseudopotential based orbital rad ius r(s)and the principal quantum number of the element concerned. A u niversal linear relationship between the Sanderson electronegativity ( SR) and this quantum scale is established. Next, we show that the stre tching mode vibrational frequencies of hydrogen (nu(Si-H)) and chlorin e (nu(Si.Cl)) in the silicon network scale linearly with this quantum scale. Predictions and identifications of defect environments around t he Si-H and Si-Cl are possible. The assignments of vibrational modes i n porous silicon are critically examined. We discuss our proposed scal e in the context of Mendeleveyan scales in general and suggest justifi cations for it. We believe that our approach can be gainfully extended to the vibrational spectra of other semiconductors.