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-consi stent linear muffin till orbital (LMTO) method, together with a local densi ty functional theory, has been employed for calculating the electronic stru cture and the atomic structures of the superlattices formed from the two di fferent types of semiconductors. In particular, we report here the results for the lattice mismatched ZnS/ZnSe superlattices in (110) geometry. We hav e performed the calculations for three strain modes: (i) free-standing inte rface, where both ZnS and ZnSe are strained: (ii) ZnS (strained) deposited on the unstrained ZnSe; and (iii) ZnSe (strained) deposited on unstrained Z nS. The calculated band offsets reveal strong sensitivity on the atomic pos itions in the interfacial region and show a non-linear behaviour with respe ct to the atomic displacements. There appear a number of interface states o f localized and resonance types which may be responsible for the sensitivit y of the band offsets on the atomic positions. (C) 1999 Elsevier Science B. V. All rights reserved.