Structural and optical studies of ZnSe epilayers, which were grown on the B side of (111)-oriented GaAs substrates, indicated the presence of tensile in-plane strains in the epilayers at room temperature. Electron microscopy observations showed that the ZnSe epilayer formed a coherent sharp interface with the GaAs substrate and consisted of crystallites which were grown in epitaxial or twin orientation with respect to the substrate, having the (111) planes oriented parallel to the interface. In addition, embedded twins were observed within the epilayer. The twin boundaries were, in general, terminated by Shockley partial dislocations, which were expected to relax the compressive lattice mismatch strain. Plastic or thermal relaxation cannot account for sign and magnitude of the observed strains. Evidence was found that the observed tensile strains were piezoelectrically induced in a depletion layer, due to Fermi level pinning at the ZnSe/GaAs interface.

Structural Properties of ZnSe Epilayers on (111) GaAs. A.G.Kontos, N.Chrysanthakopoulos, M.Calamiotou, T.Kehagias, P.Komninou, U.W.Pohl: Journal of Applied Physics, 2001, 90[7], 3301-7