RELAXATION AND MOSAICITY PROFILES IN EPITAXIAL LAYERS STUDIED BY HIGH-RESOLUTION X-RAY-DIFFRACTION

A novel nondestructive method correlating the strain gradient in parti ally relaxed epilayers with a profile of crystalline mosaicity is demo nstrated by using high resolution X-ray diffraction. By reciprocal spa ce mapping, a distribution of the scattered intensity near reciprocal lattice points was found, which is characteristic for partially relaxe d layers. This distribution is described by a relaxation-mosaicity tri angle which is modified in a characteristic way for different reflecti on orders. The increase in mosaicity with progressive relaxation is qu antified from diffraction profiles recorded along selected directions in reciprocal space. The determination of the depth profile of strain implies also the knowledge of the depth gradient of the mosaicity. The method is demonstrated for a partially relaxed ZnSe layer grown by MB E on (001) GaAs.