Kinematical simulation of high-resolution x-ray diffraction curves of GexSi1−x/Si strained-layer superlattices: A structural assessment

High-resolution x-ray diffraction (HRXRD) measurements of GexSi1−x/Si strained-layer superlattices are carried out using a four-crystal monochromator. A wide asymmetric range of extremely sharp higher order x-ray satellite peaks is observed indicating a well-defined strained-layer superlattice with abrupt interfaces. This is further confirmed by cross-section transmission electron microscopy. Using a kinematical diffraction step model which assumes ideally sharp interfaces, the thickness, strain, and composition of the GexSi1−x well could be extracted. Excellent agreement between measured and simulated x-ray satellite patterns is achieved. These results show that HRXRD together with kinematical simulation provides a powerful tool to evaluate the structural perfection of GexSi1−x/Si strained-layer superlattices.