Growth-related point defects and defect clusters in layers which had been prepared by means of molecular beam epitaxy were studied. The defect incorporation behavior was particularly studied in connection with the growth temperature, and the use of substrate bias or surfactant overlayers. Strong broad-band photoluminescence emissions arose from samples which had been grown at 420C with a negative, or floating, substrate bias. On the basis of the defect annihilation behavior during post-growth treatments which involved thermal annealing and hydrogenation, these effects were attributed to the ion bombardment-induced formation of various types of point-like defect and defect cluster. It was found that there was a correlation with the lattice distortions which were observed by means of X-ray diffraction measurements. Non-radiative defects, which suppressed luminescence emissions, were also observed by using optical deflection of magnetic resonance measurements. The results showed that care had to be taken, when growth was carried out at low temperatures, in order to reduce the incorporation of these defects into molecular beam epitaxial structures.

W.X.Ni, W.M.Chen, I.A.Buyanova, A.Henry, G.V.Hansson, B.Monemar: Journal of Crystal Growth, 1995, 157[1-4], 242-7