Measurement of the differential and integral distribution of diffuse x-ray scattering intensity from defects in thin strained layers

Double-and triple-crystal diffractometry have been used to study structural perfection of a ∼1 μm-thick Ga_1−x In_xSb_1−y As_y epitaxial film (x=0.9, y=0.8) on GaSb. It is shown that scattering from samples of this system can be divided into coherent and diffuse. The arrangement of reciprocal-lattice points of the film and substrate in the two-dimensional intensity distribution for asymmetrical reflections argues for the absence of elastic-strain relaxation. No dislocation networks are formed, and the diffuse scattering is produced by Coulomb-type defects. Localization of diffuse scattering in reciprocal space suggests that these defects reside in the epitaxial film. The diffuse-scattering distribution in asymmetrical reflections is shown to be anomalous; namely, it extends in a direction parallel to the surface and is split into two maxima. Schemes have been proposed and realized for measuring integral distributions of diffracted intensity along the surface and perpendicular to it, and their potential for studying diffuse scattering from defects is explored. Fiz. Tverd. Tela (St. Petersburg) 39, 1188–1193 (July 1997)