Electronic band structure of coherently strained GexSi1-x alloys on Si(001) substrates.

Abstract

Electronic band structure of coherently strained ${\mathrm{Ge}}_{\mathit{x}}$${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$ alloys grown on Si(001) substrates are calculated in a tight-binding framework. The empirical scaling rule has been used for considering the effects of hydrostatic strains on the energy band structures. The scaling index is determined by fitting the deformation-potential constants with their experimental values. The energy gaps and the valence-band structures of ${\mathrm{Ge}}_{\mathit{x}}$${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$/Si(001) as a function of the alloy composition x are given and the effects of the strains on the constant-energy surfaces at the top of the valence band and the effective masses of electrons and holes are discussed. Finally, the imaginary part of dielectric constant ${\mathrm{\ensuremath{\epsilon}}}_{2}$, the density of states for ${\mathrm{Ge}}_{\mathit{x}}$${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$/Si(001), and the effects of the strains on them are shown.