THE CHEMICAL BONDING IN CRYSTALS WITH CHALCOPYRITE STRUCTURE

Experimentally with x-ray spectroscopy method and theoretically using the cluster approach of the local coherent potential method the partic ularities of chemical bonds of the semiconductors AgGaS2, AgInS2, CuGa S2, CuInS2 have been investigated. The fluorescent x-ray emission K-ba nds and the absorption K-spectra (XANES) of sulphur in the compounds i nvestigated were obtained with resolution 0.2 eV. For upper part of th e valence bands the electron structure is due to the occupied d-states of the noble metal (Ag, Cu), which mix with the delocalized p-states of S. The significant mixture of these stales shows the strong covalen t bond of S atom with noble metal atom. The three maxima splitting of these states confirms the resonance character of the interaction of th ese atoms. The similarity of results for both chalcopyrite and zinc-bl end stuctures proves. that the short-range ordering determines the ele ctronic energy structure of these tetrahedral semiconductors.