Permittivity and soft mode in narrow-gap Pbsub(1-x)Snsub(x)Te(x<0.35) semiconductors

Presented are the results of theoretical studies of the effect of carrier concentration and composition X on static dielectric function and the frequency of transverse optical phonon in solid Pbsub(1-x)Snsub(x)Te solutions. It is shown that to calculate the dependence of the frequency of transverse phonon mode and the width of forbidden zone on solid solution composition and concentration it is sufficient to limit oneself to the simplest approximation for polarization operator, optical deformation potential being chosen as an adjusting parameter. The results of calculations are compared with available experimental data