Bragg-case K⃗g and K⃗0 beam double-crystal synchrotron studies of growth sectors and dislocations in synthetic diamonds

Abstract

A slab of synthetic diamond 4×4×1.5 mm3 has been studied in Bragg-case, simultaneously in reflected and transmitted beams, using a double-crystal topographic method with a synchrotron source of x-rays. The examined diamond had been grown by the reconstitution method and was of a cuboctahedral habit with two large artificially cut surfaces parallel to (001) planes. A very sensitive double-crystal arrangement was used with the 008 diamond reflexion matching the 115¯1 silicon reflexion selecting 0.802 Å radiation. Both reflected K⃗g and transmitted K⃗0 beam topographs revealed the images of dislocations and many details of the growth sector structure. The pairs of topographs thus obtained were not entirely complementary. Apart from the different foreshortening, the transmitted beam topographs were less sensitive and reproduced more distinctly defects closer to the exit surface. The results are compared with those obtained using other methods, especially the single-crystal section and projection topography. The images of dislocations in K⃗g and K⃗0 topographs were compared with theoretical images obtained by numerical integration of the Takagi-Taupin equations, including modeling of impurity segregation in growth bands and taking into account the angular divergence of the monochromatized beam. The applied method provided a reasonable correspondence between the simulated and experimental images and confirmed that the images of dislocation outcrops on the entrance surface dominate both the K⃗g and K⃗0 topographs.