It was shown that the insertion of an organometallic vapour phase epitaxial GaAs layer into a GaAs/Si epitaxial structure improved its crystallinity after cyclic annealing. The photoluminescence intensity of the upper GaAs epilayer was found to be greater than that from a normal GaAs layer. It was observed, using cross-sectional transmission electron microscopy, that the number of through dislocations was smaller for samples with the buffer layer. Most threading dislocations were confined to below the buffer layer after cyclic annealing. This was in good agreement with the photoluminescence results. The improvement was tentatively attributed to an increased concentration of Ga vacancies which migrated and relieved the tensile stress.

Reduction of Threading Dislocations in GaAs on Si by the Use of Intermediate GaAs Buffer Layers Prepared under High V-III Ratios H.Kakinuma, T.Ueda, S.Gotoh, C.Yamagishi: Journal of Crystal Growth, 1999, 205[1-2], 25-30