Characterization of Ga2Se3 at ZnSe/GaAs heterovalent interfaces

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Abstract
Despite the valence difference across the junction, it has been shown that ZnSe/GaAs epilayer/epilayer interface state densities can be reduced to values comparable to the (Al,Ga)As/GaAs interface. We have previously reported a transmission electron microscopy study indicating that ZnSe/GaAs structures exhibiting low interface state densities are associated with the formation of an interfacial layer of zinc‐blende Ga2Se3. In this letter we describe a procedure whereby an interfacial layer can be deliberately introduced prior to nucleation of ZnSe. In situ x‐ray photoelectron spectroscopy is used to study the nature of the bonding at the interfacial layer. A comparison of the Se 3d core level features from the ZnSe epilayer surface, a Se‐reacted GaAs surface, and from a separately grown Ga2Se3 epilayer, clearly indicates the same Se bonding characteristic for the Se‐reacted interfacial layer and the Ga2Se3 epilayer.