X-RAY-DIFFRACTION MEASUREMENTS FROM IMPERFECT GAAS CRYSTALS - EVIDENCE FOR NEAR-SURFACE DEFECTS

Gallium arsenide crystals with orientations [1 1 1] and [111] were measured with use of a three-crystal x-ray diffractometer. Owing to the preparation of the surface of the substrates and the growing conditions using molecular-beam epitaxy (MBE), a concentration of large defect clusters of several parts per million in the MBE-grown layers results. These defects cause considerable diffuse scattering, which is visible around the reciprocal-lattice points. Even for evaporated MBE layers with thicknesses of only about 3000, diffusely scattered intensity can be detected. © 1990 The American Physical Society.