A new version of the method for analysing peak broadening caused by local tilt distribution in double-crystal X-ray diffraction measurements

A new method of analysing X-ray peak broadening caused by local tilt distribution in mosaic structures is proposed for double-crystal X-ray diffraction measurements. In the new method, the dependence of whole peak profiles on various reflection indices hkl is analysed, whereas that of only the peak full width at half-maximum (FWHM) is analysed in a conventional broadening analysis. The theoretical formula tells us that not only the FWHM values but also the whole profiles become independent of hkl after rescaling the horizontal axis Δθ of measured patterns to Δθ/cosθ_c, where θ_c is the angle between the (001) and (hkl) planes. A new criterion is proposed to judge whether X-ray peak broadening is caused by the local tilt distribution or not; the advantage provided by the new criterion, using whole peak profiles, is high accuracy in making this judgment. It is experimentally verified that the hkl independence holds in terms of whole peak profiles. The advantage of the method is demonstrated experimentally by applying it to InAsP/InGaAsP strained layer superlattice samples.