INVESTIGATION OF NEAR-SURFACE DISTORTIONS IN SI SINGLE-CRYSTALS BU MEANS OF SPATIAL-DISTRIBUTION ANALYSIS OF REFLECTED BEAMS

A diffractometrical method for quantitative evaluation of structure pe rfection level in silicon single crystals containing various types of near surface distortions is described. The method is based on the spat ial distribution analysis of the reflected intensity in the Bragg case of diffraction. To implement the proposed approach one has to satisfy the condition of the so-called low X-ray absorption because in this c ase the penetration depth of diffracted radiation exceeds the correspo nding value of extinction length. It permits us to obtain a remarkable value of noncoherent reflectivity due to defects placed in deep (on t he extension of absorption length) regions of a crystal and therefore, to increase the sensitivity of scattering for low distortions of crys tal lattice. Using the method described here the extension of various disturbed layers as well as the level of the static Debye-Waller facto r of a crystal can be determined. The effect of surface distortions ca used by mechanical treatment and the influence of the following therma l annealing as well as irradiation by high energy protons on the defec tive structure of the samples were investigated.