Anomalous Mobility and Dielectric Singularity ofα-Sn

Abstract

The ionized-impurity-limited mobility of degenerate $n$-type $\alpha$-Sn is calculated taking into account the variation of effective mass with Fermi level and the $p$-like character of the $\alpha$-Sn conduction-band wave function. Excellent agreement with experiment is obtained over the concentration range 6×${10}^{14}$ to 1×${10}^{17}$ electrons/${\mathrm{cm}}^3$, using Fermi-Thomas screening and a $q$-independent dielectric constant. These results strongly suggest that the random phase approximation considerably overestimates the interband contribution to the dielectric function.