Strain inhomogeneity mapping in single-crystal layers and membranes by X-ray diffractometry

For the measurement of the strain distribution in single‐crystalline thin layers, it is in principle enough to measure the shift of the angular position of a single Bragg reflection. This is usually disturbed by the curvature of the specimen. Because of the strain sensitivity of different reflections, it is possible to choose two appropriate Bragg peaks which allow the elimination of the effect of any macroscopic curvature by comparing their shifts. The strain sensitivity of a strained isotropic layer under biaxial stress is presented, together with a few examples of choosing a pair of reflections. The success of the method is demonstrated by the results of a one‐dimensional scan of a strained Si membrane.