Scattering of Charge Carriers from Point Imperfections in Semiconductors

The scattering of charge carriers due to point imperfections having atomic radii different from those of host atoms is calculated for semiconductors, assuming the potential of scattering due to lattice strain to be a δ-function-like pseudo-potential for the continuous model approximation. From the calculation using the Born approximation, the interference between the strain scattering associated with the lattice distortion and the Coulomb scattering from charged centers has been found to be quite large, while no interference of scatterings between lattice vibrations and point defects has been deduced. This strain-interference effect must be an explanation of the difference in the electron mobilities between Sb-doped Ge and As-doped Ge. The validity of the approximation method adopted and the effect of the free surface of crystal are also briefly discussed.