Strain relaxation in surface nano-structures studied by X-ray diffraction methods

We study the lattice strain relaxation in pseudomorphic surface gratings using high resolution X-ray diffraction and elasticity theory. Symmetrical and asymmetrical X-ray diffraction gives evidence of a non-uniform strain relaxation in the etched structures and the creation of a periodic strain field deep in the substrate. The experimental findings are confirmed by an elasticity model which describes the interaction of the different crystalline media. By comparing the measured with calculated diffraction maps, we determine the actual strain distribution in the trapezoidal grating and in the substrate.