Reduction of dislocation densities in heteroepitaxial III−V VPE semiconductors

Abstract

Electron microscope evidence from {011} cross−sectional samples of In_xGa_1−xP/GaP is presented to demonstrate the reduction of dislocation densities in constant composition regions of {100} III−V samples prepared by vapor−phase epitaxy with compositional grading having over−all misfit strains as high as 3.7%. Dislocations are shown to be confined to the graded region by an abrupt compositional step in both step− and continuous−graded samples. The crystal growth technique described works well for epitaxial layers which are in compression but not for those which are in tension.