STRAIN CHARACTERIZATION IN SI/SIGE SUPERLATTICES BY CONVERGENT BEAM ELECTRON-DIFFRACTION

A method is described whereby strain in Si1-xGex/Si(001) superlattices can be derived using convergent beam electron diffraction (CBED) and large angle CBED. The method uses plan-view samples, thus avoiding strain relaxation in cross-sectional samples. Rocking curves for reflections from planes inclined to the interface were asymmetric and showed superlattice peaks whose intensities were sensitive to strain. A quantitative analysis of the experimental results using kinematical and dynamical simulations showed good agreement for the expected strains to within an accuracy of +/- 20%.