PROFILING OF DOUBLE-CRYSTAL X-RAY-DIFFRACTION OF INGAAS EPILAYERS GROWN ON GAAS

In0.12Ga0.88As epilayers were grown by a direct growth (DG) process and a two step growth (TG) process and analyzed by measuring the profile of the diffraction angle and full width at half maximum (FWHM) of double-crystal X-ray diffraction (DXRD). In the case of the DG process, rectangular-shaped grains are surrounded by highly dislocated boundaries, which are observed as crosshatches. Profiles of DXRD indicate that both epilayer and substrate of as-grown samples contain a strain. In the case of TG process, both the region growing coherently and the region containing a high density of defects appear along the heterointerface and the latter acts as an absorber of misfitstrain. As a result, the epilayer is almost free from strain.