Accommodation of misfit during the initial growth of GaAs on {111}-Si

Abstract
Growth of GaAs on (111) Si substrates involves the nucleation and growth of epitactically-oriented GaAs islands. The islands are predominantly hexagonal in shape with their sides parallel to 〈11∼2〉 directions. Islands which are ∼0·2 μm wide have been studied in plan view by strong- and weak-beam diffraction contrast. Similar samples have been studied by HREM in cross-section. Different contrast features are present which indicate that more than one mechanism may operate to accommodate the misfit. Both perfect, 1/2〈110〉 and partial, 1/6〈112〉, dislocations appear to be present. The GaAs can form with either the same orientation as the Si or with a twinned relationship.