Images of local tilted regions in strain-relaxed SiGe layers

Strain-relaxed Si1-xGex films have been investigated using X-ray microdiffraction with a diffracted beam footprint of 0.3 μm×2 μm. Intensity variations in the diffracted beam at different positions on the sample are due to the presence of local tilted regions which are larger in area than the diffracted X-ray beam. These regions are shown to have the same lattice parameter but different orientation with respect to the Si substrate. These regions arise from dislocation pileups, which consist of a larger number of dislocations when larger mismatch strain is relieved.