Characterization of epitaxial films by grazing-incidence X-ray diffraction

Grazing-incidence X-ray diffraction, a recently developed, powerful, non-destructive and surface-sensitive technique, allows characterization of epitaxial films with thicknesses down to a few atomic layers. Lattice parameters, strains and crystallite sizes can be determined parallel to the interface, complementing results obtained for these parameters in other directions by conventional Bragg diffraction. Epitaxial relationships between substrate and film and their orientational spread can be determined uniquely, and minority domains with an orientation or strain state different from that of the main mass of the film can frequently be detected with this technique while they are not observable with conventional diffraction. The power of this technique, as performed in our laboratory with a 12 kW rotatinganode X-ray generator, is demonstrated with various examples of epitaxial systems: Cu/Al2O3(0001), W/Al2O3(1102), molybdenum and niobium on GaAs(001) and GaAs(111), GaAs/Al2O3(0001) and InAs/GaAs(001). © 1987.