Electronic Structure of Strained Sin/Gen(001) Superlattices
Using the empirical tight binding method we have investigated the electronic properties of the Sin/Gen(001) strained superlattices as a function of the superlattice periodicity and the band misfit. For n ≥ 3, we have found some conduction band states localized in Si, and some in Ge, presenting a band discontinuity quite different from the staggered type-II. The hole states localized in Ge appear for n ≥ 4. The difference between the direct and indirect band gaps is reduced from 0.39 eV for n = 3 to 0.035 eV for n = 6 which can be considered to be quasi-direct.