Electronic structure of non-centrosymmetric AgCd2GaS4 and AgCd2GaSe4 single crystals

► XPS spectra of AgCd2GaS4 and AgCd2GaSe4 single crystals have been measured. ► High chemical stability of the (0 0 1) surface is characteristic of the single crystals. ► Electronic structure of AgCd2GaS4 has been calculated by the FP-LAPW method. ► The theoretical band-structure data for AgCd2GaS4 are confirmed experimentally. ► Second harmonic generation efficiency of AgCd2GaS4 has been investigated.