THE IMAGES OF MISFIT DISLOCATIONS IN BRAGG-CASE SYNCHROTRON SECTION TOPOGRAPHY

Silicon epitaxial layers deposited on substrates doped with boron and containing certain amount of misfit dislocations were studied by means of back-reflection synchrotron section topography. Samples with diffe rent curvature determined by substrate thickness and status of their b ack sides were examined. When the curvature of the sample was negligib le the section pattern consisted of two stripes corresponding, respect ively, to the layer and to the substrate. Misfit dislocations were rev ealed in the direct contrast located mostly in the vicinity of the sub strate stripe. In the samples with radius of curvature smaller than 10 0 m additional interference fringes were observed in a wide area behin d the main two stripes. The sequence of these interference fringes was dependent on the curvature of the sample and differed from that of be nt substrate wafers of the similar curvature. As a consequence the ima ges of misfit dislocations became much more extended and contained man y characteristic details. The character of experimental misfit disloca tion images both in the case of flat and bent crystals was reproduced using numerical integration of the Takagi-Taupin equations.