ABSTRACT
The band structure of semiconductors is mainly influenced by the lattice type, the bonding distance, and the ionicity of bonding partners. The dominant contribution to the frequency dependence of the dielectric function of semiconductors arises from electronic interband transitions between occupied valence band and empty conduction band states. In the visible and near-infrared spectral regime the fundamental absorption processes can be easily explained considering the electronic band structure of semiconductors and keeping in mind the conservation laws of energy and momentum. This chapter treats the corresponding bandgap changes within a linear approximation, which delivers enough accuracy within a few percent volume change because the data for deformation potentials and indirect/direct conduction band crossover are uncertain by at least 10%. The lowest energy transition is related to the light hole valence band for biaxial tensile strain, whereas compressive biaxial strain moves up the heavy hole band.
