AB-INITIO PSEUDOPOTENTIAL CALCULATIONS OF THE BAND LINEUPS AT STRAINED ZNS ZNSE INTERFACES - INCLUDING THE 3D ELECTRONS OF ZN AS VALENCE STATES/

A first-principles pseudopotential approach has been used to calculate the valence-band offset (Lambda(upsilon)) at strained ZnS/ZnSe (001) interfaces, and the structural and electronic structure properties of ZnS and ZnSe. In these calculations the semicore 3d electrons of Zn ar e included as relaxed valence states. Three strain configurations, cor responding to growth on ZnSxSe1-x (001) (with x=0, 0.5, and 1) substra tes were considered. We found that Lambda(upsilon) varies almost linea rly between 0.43 and 0.78 eV in the above strain range, with the state at the top of the valence band in ZnSe being higher in energy. The av erages of Lambda(upsilon) and the conduction-band offset are found to be independent of the strain state and with values of 0.50 and 0.23 eV , respectively. These results and that of the other studied properties are found to be in excellent agreement with experiment and ah-electro n calculations. The charge density associated with the d bands shows s ome deviations from being spherically symmetric around the Zn ions and has appreciable magnitude in the anions regions, which suggests that the dp hybridization is quite strong.