Tight-binding study of the strained monolayer superlattices (Si)1/(Si1−xGex)1 (100)

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Abstract
Electronic structures of strained monolayer superlattices (Si)1/(Si1−xGex)1 are calculated within the tight‐binding scheme by taking into consideration the effect of stress on atomic interactions. Gap variations with composition and band offsets for different strain conditions are obtained. When Si(Ge) is grown on cubic Ge(Si) with stress to match the lattice constant of the substrates, the calculated nonmonotonic behavior of the superlattice Eg(x) curve can be attributed to a similar phenomenon of the bulk alloy under the same strain. The energy band of the monolayer Si/Ge shows the zinc blende symmetry with a Si‐like feature. Starting with the virtual crystal approximation for the calculation of gap and density of states, it is found that further modification using coherent potential approximation is not very significant.