Ionized impurity scattering in semiconductors with spatially variable dielectric functions

Abstract

A spatially-dependent dielectric function $\epsilon \mathrm{}\left(r\right)\mathrm{}$ based on the Penn model is incorporated into existing theories of ionized impurity scattering. For the case of Si (Ge) it is shown that such an incorporation lowers the calculated mobility by a factor of 2.5 (3.0) at low-impurity concentrations. At high-impurity concentrations, the effect of introducing $\epsilon \mathrm{}\left(r\right)\mathrm{}$ into the formalism is to lower the calculated mobility by as much as several orders of magnitude. We conclude that analysis of mobility data may thus be used as a sensitive probe of the spatial dependence of the dielectric function.