Electronic structure of non-centrosymmetric Ag2HgSnS4 single crystal

X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion irradiated surfaces of Ag2HgSnS4 single crystal grown by the Bridgman-Stockbarger technique have been measured in the present work. Ag2HgSnS4 single-crystalline surface was found to be sensitive to Ar+ ion-bombardment: significant modification in top surface layers was induced leading to abrupt decreasing the content of mercury atoms in the layers. X-ray emission bands representing the energy distribution of the valence Ag d and S p states were recorded. S 3p states contribute predominantly in the central and upper portions of the valence band, with significant contributions in the lower portion of the valence band of the Ag2HgSnS4 single crystal. Ag 4d states contribute mainly in the central portion of the valence band of the compound under consideration.