The spectral distribution of the hole photo-ionization cross-section of the deep S center was measured, at temperatures ranging from 75 to 297K, by using the steady-state photo-current technique. The zero-phonon hole binding energies of the deep donor level were determined at these temperatures by using a numerical fitting procedure. It was found that the temperature dependence of the hole binding energy could be accurately described by using a novel analytical formula with a zero-temperature binding energy of 0.557eV. Further analysis of the data yielded a lattice adjustment energy (Franck-Condon shift) of 0.051eV, and an associated average phonon energy of 0.033eV.

H.Pettersson, R.Pässler, F.Blaschta, H.G.Grimmeiss: Journal of Applied Physics, 1996, 80[9], 5312-7