(II–VI)m(IV2)n (110) superlattice: interfacial chemistry, electronic structure, and optical property

The detail calculations of the electronic and optical properties of the (ZnS)n(Si2)m and (ZnSe)n(Ge2)m (110) superlattices are performed by a semiempirical tight-binding method with a wide range of n, m ≤ 20. Interfacial band structures and planar average of charge densities of states are presented for the ZnSSi and ZnSeGe (110) boundaries. An empty interface band is identified in the upper region of the gap of the ZnSSi superlattice, which extends over an extended region of k space. No interface state, however, is found in the thermal gap of the ZnSeGe system. Furthermore, some widely used pseudobinary semiconductor alloys in the interface region are studied to show the important role of interfacial chemistry in II–VI compound growth on silicon. Finally, the calculated absorption spectra of the superlattice are found to be quite different from those of the corresponding bulks, but fairly close to their average.