STUDY OF STRUCTURAL EVALUATION FOR CRYSTAL BY USED BORRMANN EFFECT

本研究的目的是分析在Ga和As K吸收边附近不同原子共振散射条件下记录的GaAs200反射X射线平面波形貌图中晶格缺陷对比度的变化。在Laue情况下，用同步辐射在Ga和As K吸收边附近的KEK-Pf中拍摄了GaAs200反射X射线的平面波形貌图。由晶格缺陷引起的形貌收缩是通过将X射线能量调节到四个典型的共振散射条件来改变的。当Borrmann效应消失时，观察到晶格缺陷的清晰图像。当Borrmann效应明显时，观察到位错周围的晶格扭曲图像，并通过改变共振散射的位相因子来反转其对比度。在Bragg情况下，利用同步辐射拍摄了Ge844反射的平面波在GeK吸收边附近的形貌。随着X射线能量的变化，晶格缺陷的黑白对比度也发生了反转，形貌图像也发生了变化。用共振动力学绕射理论对这些现象进行了分析。提出了对比度反转的两个原因，一是由于消光效应的反常吸收和平均吸收的增强而导致吸收增加，二是由于Borrmann效应的反常传输和平均吸收和消光效应的减弱而导致吸收减少。同时发现，消光效应占主导地位的图像与Borrmann效应占主导地位的图像有很大的不同。关于同步辐射地形的这些性质有望成为检查结构缺陷的一个有吸引力的工具。

The purpose of this research is the analysis about the changes of the contrasts for lattice defects in X-ray plane wave topographs, which were recorded for GaAs 200 reflection at different conditions of atomic resonant scattering near the K-absorption edges of Ga and As.In the Laue case, the plane wave topographs of X-rays for GaAs 200 reflection were taken using synchrotron radiation in KEK-PF near the K-absorption edges of Ga and As. The topographic contracts caused by lattice defects were changes by tuning X-ray energy to four typical resonant scattering conditions. The sharp image of lattice defect was observed when the Borrmann effect disappeared. When the Borrmann effect was conspicuous, the image of lattice distortion around a dislocation was observed, and its contrast was reversed by changing the phase factor of resonant scattering.In the Bragg case, the plane-wave topographs with Ge844 reflection were taken near the Ge K-absorption edge by using the synchrotron radiation. The black-white contrasts of lattice defects were reversed besides the general changes in topographic images with the changes of X-ray energy. These phenomena have been analyzed by the resonant dynamical theory of diffraction. The explanation is brought out that two elements are responsible for the inverse of contrast, one is that the absorption increases due to the anomalous absorption of the extinction effect and the strengthening of the mean absorption, and another is that the absorption decrease due to the anomalous transmission of the Borrmann effect and the weakening of the mean absorption and the extinction effect. Meanwhile, it is revealed that the images in which the extinction effect is dominant are different greatly from the ones in which the Borrmann effect is dominant. Such properties about synchrotron radiation topography can be expected to turn out to be an attractive tool to examine structural imperfections.