An x-ray photoelectron spectroscopy study of bonding at II-VI/III-V heterovalent interfaces

In this paper in situ x-ray photoelectron spectroscopy (XPS) is used to study the nature of the bonding at ZnSe/GaAs and CdTe/InSb interfaces grown by molecular-beam epitaxy. X-ray photoelectron spectra support the transmission electron microscopy evidence that ZnSe/GaAs MIS capacitors exhibiting low interface state densities are associated with the formation of an interfacial layer of zinc blende Ga₂Se₃. An interfacial layer can be deliberately introduced by reacting an As deficient GaAs surface with an incident Se flux. A comparison of the Se 3d core level features from the ZnSe epilayer surface, a Se-reacted GaAs surface, and from separately grown Ga₂Se₃ epilayers, clearly indicate the same Se bonding characteristic for the Se-reacted layer, and the Ga₂Se₃ epilayer. A parallel XPS study of CdTe/InSb interfaces leads to the conclusion that there is a general tendency for the formation of a III-VI interfacial compound when forming a II-VI-on-III-V junction.