Investigation of Near Surface Distortions in Si Single Crystals by Means of Spatial Distribution Analysis of Reflected Beams

Abstract

A diffractometrical method for quantitative evaluation of structure perfection level in silicon single crystals containing various types of near surface distortions is described. The method is based on the spatial 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 case the penetration depth of diffracted radiation exceeds the corresponding value of extinction length. It permits us to obtain a remarkable value of noncoherent reflectivity due to defects placed in deep (on the extension of absorption length) regions of a crystal and therefore, to increase the sensitivity of scattering for low distortions of crystal lattice. Using the method described here the extension of various disturbed layers as well as the level of the static Debye-Waller factor of a crystal can be determined. The effect of surface distortions caused by mechanical treatment and the influence of the following thermal annealing as well as irradiation by high energy protons on the defective structure of the samples were investigated.PACS numbers: 81.40.-z, 61.10.-i X-ray diffractometry based on determination of the integral characteristics (i.e. averaged over a scattering volume) of defect stuctures is one of the most effective methods for diagnostics of real single crystals. Now the nondestuctive methods of rapid stucture perfection control are developed and widely used in scientific and industrial laboratories. The methods, in particular, permit us to identify the type of predominate defects distributed homogeneously over the bulk of a crystal as well as to determine their mean dimension and concentration [1, 2].(309)