Lorentz number and Hall factor in degenerate semiconductors during resonance scattering of charge carriers

Abstract

In highly degenerate semiconductors, the Lorentz number L and Hall factor A R differ significantly from universal constants π2/3 and 1, respectively, due to the pronounced energy dependence of the relaxation time during resonance scattering of carriers. The values of L and A R are calculated for various values of the resonant impurity bandwidth, band filling with current carriers, and the relative contribution of resonance scattering. The available published data on the bandwidth of thallium impurity states in lead telluride, where intense resonance scattering of holes was observed, are discussed. The previously obtained data on the energy of Tl in PbTe resonant states were corrected taking into account the calculated Hall factor. An analysis of the experimental data on the dependence of the PbTe:Tl thermal conductivity on the temperature and content of additional Na dopant both showed that phonon scattering by polarized regions around charged impurity atoms is negligible and confirmed the results of theoretical calculations of the Lorentz number at dominant resonance scattering of holes.