Coulomb Effects at Saddle-Type Critical Points in CdTe, ZnTe, ZnSe, and HgTe

Abstract
The Kane model for saddle-point excitons is applied to CdTe, ZnTe, ZnSe, and HgTe by studying the shape of the imaginary part of the dielectric constant ε2 obtained by reflectivity measurements at 10 °K. We have obtained |m3m1|=28 for CdTe and 20 for ZnTe but we have not been able to measure the ratio for ZnSe or HgTe.