Band structure and symmetry analysis of coherently grown Si1-xGex alloys on oriented substrates

A semiempirical tight-binding method was used to calculate the band structures of Si 1-x Ge x alloys coherently grown on (001)-, (111)-, and (110)-oriented Si 1-y Ge y substrates. The distorted lattice and Brillouin zone, as well as the band-edge splittings and shifts which vary with the Ge content of both the Si 1-x Ge x strained layer and the substrate, are given. The band structures and symmetry properties of the coherently strained Si 1-x Ge x alloys along high-symmetry lines of the distorted Brillouin zone are analyzed