Elimination of extrinsic components overlapping lattice distortion variations of a silicon single crystal obtained by double-crystal X-ray topography

Variations in lattice plane spacing and lattice plane orientation, i.e. Δd/d and Δα, reflect variations in lattice distortion in a single crystal. Double-crystal X-ray topography (DCT) using synchrotron radiation can be used to measure Δd/d and Δα of a silicon single crystal. However, both Δd/d and Δα measured using DCT are always overlapped by extrinsic components, showing particular long-range variations. The extrinsic components should be eliminated from the measured Δd/d and Δα for quantitative characterization of silicon single crystals. A sample-rotation and area-detector-traverse (RT) method, applicable to X-ray optics for DCT, has been newly developed. The extrinsic components are eliminated by modification of the intensity distribution on the X-ray topographs using the RT method. From theoretical considerations, it is confirmed that the extrinsic components are mainly due to the (+,−) non-parallel setting between the monochromator and the collimator, and a minute bend in the sample due to its physical restraint.