Carrier scattering by neutral divalent impurities in semiconductors: Theory and experiment

We have developed a theoretical model describing carrier scattering by divalent impurities in semiconductors. The mobility predicted by the model based on the scattering of electrons by helium atoms shows excellent agreement with the low-temperature mobilities measured for three Ge samples doped with different double acceptors; Be, Zn, and Hg. We show that the scattering cross sections of these double acceptors are the same despite the large difference in ionization energies. This supports our assumption that the contribution of the central-cell potential to neutral impurity scattering is negligible.