Interfacial superstructures studied by grazing incidence x-ray diffraction

Abstract

Surface superstructures (reconstructed structures) have been observed by many techniques. However, it has not been easy to confirm that a superstructure does exist at an interface between two solid layers. We have observed superstructures at the interface between two solid layers by a grazing incidence X-ray diffraction technique with use of synchrotron radiation. We have observed the interfacial superstructures between amorphous silicon (a-Si) and Si(111)-7×7, Ge0.2Si0.8(111)-5×5 or B(√3 ×√3)/Si(111) and have also shown the existence of the interface between an epitaxial Si(111) layer and B(√3×√3)/Si(111). Interfacial superstructures between Al or other metals and GaAs(001) have been found. Such superstructures may be relevant for the understanding of Schottky barrier formation. In addition, interfacial superstructures between AIN and GaAs(001) layers, both deposited on a GaAs(001) substrate by the metalorganic chemical vapor deposition (MOCVD) method, have been found to exist.