The screening distance for the ionized impurity potential surrounded by holes in the warped and non-parabolic valence band is obtained by using Dingle's self-consistent method.
By comparing this distance with the previously and commonly used distances RCW and RBH, we can discuss the relation of the two ionized impurity scattering theories i.e., the theory proposed by Conwell and Weisskopf (the CW model) and that proposed by Brooks and Herring (tne BH model). We have investigated the validity for each model.
The calculated drift mobility, in which the lattice scattering including the effect of non-polar optical phonons and the impurity scattering due to both ionized and neutral centers are taken into account, shows a good agreement with experimental results so far if the existence of three subbands and the interaction between those subbands would be considered.