Formation of planar defects in the epitaxial growth of GaP on Si substrate by metal organic chemical-vapor deposition

Abstract

The very small lattice mismatch between GaP and Si implies negligible coherency strains when GaP is grown epitaxially on Si. Moreover, GaP is expected to show little plasticity below ∼700 °C. It is thus unlikely that either the small coherency strains or the thermal mismatch stresses would be sufficient to generate the partial dislocations responsible for planar defects in an epitaxial film grown at temperatures below ∼700 °C. However, high-resolution electron microscopy micrographs of the early stages of epitaxial growth of GaP on Si at 500 °C show a high density of stacking faults and microtwins in the film. It is argued that in epitaxial growth processes, planar faults are not formed as a result of interfacial stresses; instead, a mechanism for the formation of stacking faults and twins is proposed which is based on errors in the stacking of close-packed planes in the early stages of nucleation and growth.