QUANTITATIVE STRAIN MAPPING USING HIGH-RESOLUTION ELECTRON-MICROSCOPY

Lattice images as obtained by high-resolution electron microscopy are used to quantify strain and strain profiles in semiconductor layer str uctures. Inherent parts of the analysis are the definition of spatial resolution and detection limit on the basis of a quantification of noi se. As an application the tetragonal strain in pseudomorphic InxAl1-xA s heterostructures is analyzed. The detection limit is 2.8% strain at a spatial resolution of 0.4 x 0.4 nm(2) using a 2 sigma-criterion. If resolution along the heterostructure is reduced by averaging, even 0.2 % strain can be detected at a spatial resolution of 0.4 x 35 nm(2).