Interface defect structure of metal-organic chemically vapour-deposited InP and GaAs on Si(111)

Abstract

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