STRUCTURE PERFECTION STUDY OF CRYSTALS CONTAINING MICRODISTORTIONS AND MACRODISTORTIONS BY X-RAY ACOUSTIC METHOD

The X-ray acoustic method for determination the structure perfection i ntegral characteristics is suggested for slightly imperfect dislocatio n-free crystals. The method is suitable for investigation of a crystal disturbed both by localized (microdefects) and by distributed (macros trains) structure defects. It is based on the analysis of dependence o f the distance DELTAx between two minima, arising in the spatial inten sity profile I(x) of the X-ray beam diffracted by acoustically excited crystal, upon ultrasound frequency nu(s). Using the data DELTAx(nu(s) ) for two selected reflections, we calculated the values of the extinc tion lengths A which enabled us to identify the predominate type of st ructure disturbances as well as to estimate the static Debye-Waller fa ctors e(-L) and the period of the main macrodeformation lambda(M) for a sample containing simultaneously microdefects and periodic long rang e deformations. Such approach was used for studying the structure perf ection of Czochralski-grown (Cz) and float-zone (FZ) silicon crystals.