Combining high-resolution X-ray diffractometry and topography

Multiple-crystal diffraction profiles and multiple-crystal topography have been combined to characterize semiconductor materials. X-ray topographs have been measured on the same region of the sample as the diffraction profiles and diffraction space maps, by insetting a film cassette in the diffracted beam path of a high-resolution diffractometer. This has proved to be a very powerful combination for providing a deeper understanding of the structural features that give rise to the high-resolution diffraction profiles. The data collection mode is discussed and the problems associated with interpreting `rocking curves' of imperfect materials. The misorientation and nature of the mosaic blocks in semi-insulating GaAs have been revealed by this method.