X-ray diffraction measurements of "thin" (1-1000 nm) films using conventional θ/2θ scanning methods generally produces a week signal from the film and an intense signal from the substrate. One of the ways to avoid intense signal from the substrate and get stronger signal from the film itself is to perform a 2θ scan with a fixed grazing angle of incidence, popularly known as GIXRD. The fixed angle is generally chosen to be slightly above the critical angle for total reflection of the film material.
Figures 1 and 2 show a comparison of both a GIXRD analysis (Figure 1) and a conventional θ/2θ analysis (Figure 2) of a thin film of CdSeS on graphite taken with the Ultima IV multipurpose diffraction system. The GIXRD scan was collected with a grazing incidence angle of 0.45°. While the data from the conventional scan reveals little information from the film, showing only the graphite substrate peaks, the GIXRD data provides information from the main CdSeS layer as well as a CdS component of the film.