Effect of atomic relaxation on the valence band offset and the interface states in ZnS/ZnSe(110) superlattices

A first principles scalar relativistic version of full potential self-consistent linear muffin till orbital (LMTO) method, together with a local density functional theory, has been employed for calculating the electronic structure and the atomic structures of the superlattices formed from the two different types of semiconductors. In particular, we report here the results for the lattice mismatched ZnS/ZnSe superlattices in (110) geometry. We have performed the calculations for three strain modes: (i) free-standing interface, where both ZnS and ZnSe are strained: (ii) ZnS (strained) deposited on the unstrained ZnSe; and (iii) ZnSe (strained) deposited on unstrained ZnS. The calculated band offsets reveal strong sensitivity on the atomic positions in the interfacial region and show a non-linear behaviour with respect to the atomic displacements. There appear a number of interface states of localized and resonance types which may be responsible for the sensitivity of the band offsets on the atomic positions. (C) 1999 Elsevier Science B.V. All rights reserved.