NONUNIFORM STRAIN PROFILES IN CUBIC CDS/GAAS FILMS MEASURED BY REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION AND RAMAN-SPECTROSCOPY

We report a study of the strain relaxation in zinc-blende CdS films grown on GaAs by molecular beam epitaxy. We use Raman spectroscopy to determine the depth dependence of the strain profile. This dependence is compared with the instantaneous surface strain relaxation measured by reflection high energy electron diffraction during growth. The Raman results show that the strain profile determined by RHEED remains largely "frozen" in the final sample. It is only near the heterostructure interface, where the strain is large, that evidence of additional relaxation is found in the Raman spectrum.