Morphology and size distribution of gold nanoclusters in a−C:H films studied by grazing incidence small-angle x-ray scattering

We present a morphological study of gold-containing amorphous hydrogenated carbon films (a-C:H/Au) grown by a combined physical vapor deposition/plasma-assisted chemical vapor deposition process. By using grazing incidence small-angle x-ray scattering (GISAXS) we show that isolated Au nanoclusters are regularly distributed within the a-C:H matrix. From the GISAXS analysis, which we based on the local monodisperse approximation, the shape, size, and correlation distance of the nanoclusters as well as the size distribution both in the film plane and in the film growth direction are determined. We show that the nanocomposite films consist of an assembly of prolate and oblate ellipsoids (spherical on average, however) having a broader size distribution in the film plane than in the perpendicular direction.