We applied grazing incidence x-ray specular and non-specular reflectivity (
GIXR) and small-angle x-ray scattering (SAXS) to study the surface roughnes
s of gold films on quartz glass substrates. Two model systems were prepared
: one series of Au films was sputtered in Ar at 3 x 10(-3)mbar (Au1 films)
and one in residual air at 3 x 10(-1) mbar (Au2). The combined x-ray experi
ments showed that the Aul films are compact and smooth, with-mean-square (r
ms) roughness values too low to be quantified by means of atomic force micr
oscopy (AFM) or SAXS. The surfaces of film and substrate exhibit a strong c
ross correlation that is gradually lost with increasing film thickness. The
surface height-height correlation functions are well described by a self-a
ffine model. In contrast, as directly proved via AFM, the Au2 films consist
of islands that are coarsening with increasing film thickness. The film su
rface showed no cross-correlation with the substrate surface at all. The SA
XS curves from the Au2 films were attributed to a volume scattering effect,
by interpreting the films in terms of a two-dimensional array of hard hemi
spheres. Copyright (C) 1999 John Wiley & Sons, Ltd.