Band structures ofSixGe1−xalloys

By starting from realistic band structures of the constituent materials, the electronic structure of ${\mathrm{Si}}_{\mathrm{x}}$ ${\mathrm{Ge}}_{1\mathrm{-}\mathrm{x}}$ alloys are obtained in the coherent-potential approximation (CPA). Various quantities, including the bowing parameter of the fundamental band gap and the energies of several optical gaps, the masses, and the linewidths of the $E_0$ and $E_1$ transitions, are calculated on the basis of both diagonal and off-diagonal CPA. All of the band-energy and linewidth predictions are in good agreement with experiments. Furthermore, the theory yields an alloy-scattering-limited electron-drift mobility in qualitative agreement with experimental results.