The coalescence of GaP islands, grown onto Si(001), Si(111), Si(110) and Si(113) surfaces by using chemical beam epitaxy, was investigated by using high-resolution transmission electron microscopy. Stacking faults and first-order twins were observed within islands before coalescence, and resulted from stacking errors during growth on the smaller P-terminated {111} facets of GaP islands. Following island coalescence, complex moiré fringes were observed which were contiguous with highly-faulted {111} planes within epitaxial layers grown on all 4 substrate orientations. They were attributed to multiple twinning. Second-order and third-order twins were also observed within (111) and (110) layers, and their formation was attributed to successive twinning on differently inclined {111} facets. Among the 4 orientations, coalesced growths on the Si(111) surface were the most defective. This was suggested to be caused by a higher density of P-terminated {111} facets on islands grown on the Si(111) surface.

Stacking Faults and Twins in Gallium Phosphide Layers Grown on Silicon. V.Narayanan, S.Mahajan, K.J.Bachmann, V.Woods, N.Dietz: Philosophical Magazine A, 2002, 82[4], 685-98