X-RAY-ANALYSIS OF STRAIN RELAXATION IN STRAINED-LAYER SUPERLATTICES

Theoretical simulations of x-ray double-crystal-diffraction rocking cu rves for strain-relaxed superlattices have been successfully carried o ut based on x-ray dynamical diffraction theory. The strain relaxation, the misorientation between the superlattice layers and the substrate, and the effect of peak broadening due to the formation of misfit disl ocations have been taken into account. The influence of possible strai n relaxation mechanisms and relaxation ratios on the rocking curves ha ve been investigated. It was found that both the mechanism and degree of the strain relaxation of the superlattice can be determined by fitt ing the angular positions and the relative intensities of the experime ntal superlattice satellites. By using this method, an InxGa1-xAs/GaAs superlattice sample and a GexSi1-x/Si superlattice sample were analyz ed. The different strain-relaxation mechanisms were found in these two samples.