Double-crystal X-ray diffractometry in the role of X-ray standing-wave method

It is shown that the atomic displacements (induced by foreign layers) comparable with or smaller than the interatomic distances can be detected in perfect multilayer systems by double-crystal X-ray diffractometry alone. It was earlier thought that the detection of displacements as small as those was accessible only to the specific methods such as the X-ray standing-wave method. The measurements were carried out on a GaAs/InAs/GaAs system, where InAs was a foreign layer. Its thickness did not exceed three monolayers, while the structure was of the insular type and represented a set of separate quantum dots. The displacement of the capping GaAs layer relative to the GaAs buffer was measured with an accuracy of less than 0.1 of the thickness of the atomic layer. (C) 2001 MAIK Nauka/Interperiodica.