Model Calculation of the q-Dependent Dielectric Function of Some Zinc-Blende Semiconductors

A generalization of the Penn-model dielectric function containing two energy gaps is used to calculate ɛ(q) for a number of semiconductors of the zinc-blende family. The results are in reasonable agreement with those of studies based on complete-zone integration. We show the importance of including the details of the band structure in discussing ɛ(0).