Layers of ZnSe were grown using molecular-beam epitaxy onto GaAs substrates, which had been deoxidized by atomic H, at various temperatures. The surface roughness of the substrate was measured by means of atomic force microscopy, and that of the growing ZnSe layers was deduced from atomic force microscopic measurements and from the full-width at half-maximum of reflection high-energy electron diffraction during nucleation and layer growth. It was found that there was a marked effect of the substrate temperature, during deoxidization, upon the surface roughness and the density of extended defects in the ZnSe layers. The density of the extended defects was measured by using high-resolution X-ray diffraction and spatially resolved cathodoluminescence images from a defect-related Y0 emission at about 474nm. The intensity ratio of the defect-related Y0 emission to the near-bandedge excitonic emission was proportional to D2.9, where D was the density of extended defects in the layer. This relationship was explained in terms of a model which assumed the occurrence of radiative and non-radiative recombination of bound excitons as well as the radiative recombination of electron-hole pairs via recombination centres which were involved in the Y0 transition.

B.Buda, C.Wang, W.Wrede, O.Leifeld, D.J.As, D.Schikora, K.Lischka: Semiconductor Science and Technology, 1998, 13[8], 921-6