Impurity scattering of warm holes in germanium and silicon

Abstract

Warm hole mobility, namely that of the coefficient β=(μ−μ 0)/μ 0 E 2 is strongly affected by the number of impurities. We measured this value for relatively pure p-type germanium and silicon for different orientations and found no anisotropy contrary to that observed in previous experiment for relatively impure samples. In addition a comparison is given between experimental and theoretical β-values. In the case of p-type silicon it is sufficient to take into account acoustic phonon and ionized impurity scattering to achieve agreement between measured and calculated β-vales. In the case of p-type germanium we had to take into account additional optical phonon scattering for the energy relaxation. Due to the non-Maxwellian distribution only a smaller amount of this optical phonon scattering gives agreement with the experimental data.