INTERFACE DEFECT STRUCTURE OF METAL-ORGANIC CHEMICALLY VAPOR-DEPOSITED INP AND GAAS ON SI(111)

GaAs and InP were grown on Si(111) by low-pressure metal-organic chemi cal vapour deposition and the interfaces were studied by weak-beam and high-resolution transmission electron microscopy. Both cases represen t highly mismatched heteroepitaxial systems which form hexagonal misfi t dislocation networks consisting of partial edge dislocations which a ccommodate more than 95% of the misfit. The experimental growth condit ions were chosen such as to be compatible with integrated Si-device pr ocessing. Tn the case of GaAs the network nodes are only partially ext ended whereas for InP they are fully extended. A thin region in the In P layer close to the interface contains a high density of stacking fau lts and microtwins, the bounding partial dislocations of which contrib ute to strain accommodation. In the upper part of both layers open-end ed stacking-fault tetrahedra exist, relieving stress. Growth on {111} planes produces a low density of threading defects and therefore is pr omising for the growth of InP and GaAs on V-grooved Si(001) substrates with {111} side walls.