Surface Structure and Patterns by GISAXS/GIWAXS

Grazing-incidence X-ray scattering combines SAXS and WAXS in a geometry that enhances sensitivity to thin films and near-surface structures. The resulting 2D detector images contain complementary information about mesoscopic morphology (GISAXS) and crystalline structure (GIWAXS).

From these patterns, the techniques provide access to:

• Lateral and vertical periodicities, observed as characteristic scattering maxima or Bragg features that reflect long-range or medium-range order in the film
• Characteristic length scales, such as in-plane domain spacing, feature size, pore dimensions, or layer thicknesses, derived from the positions of small-angle scattering features
• Orientation and texture of nanostructures, obtained from the angular distribution of scattering intensity in the 2D pattern
• Crystalline packing within thin films, characterized by GIWAXS peak positions, shapes, and relative intensities, giving insight into unit cell parameters and crystal orientation
• In-plane versus out-of-plane correlations, revealed by the distribution of intensities along in-plane and out-of-plane directions, indicating anisotropy and preferred orientation in the film

Figure 1. Wedge corrected grazing incidence wide angle x-ray scattering data acquired on a P3HT:PCBM thin film on a silicon substrate. processed with XSACT Pro to highlight in-plane and out-of-plane structural motifs.

Moreover, tructural parameters can be extracted either directly from the 2D scattering maps or from 1D cuts along selected directions (in-plane, out-of-plane, or along specific reciprocal-space paths), depending on the question and level of detail required.

GISAXS and GIWAXS apply broadly to thin films and surface-engineered materials whose structure is confined near the interface. For example, they are well suited for:

• Nanopatterned surfaces
• Nanostructured or porous thin films, including block-copolymer templated materials
• Layered or nanolamellar systems, such as polymer or inorganic multilayers
• Hybrid or inorganic thin films, including oxides, semiconductors, and sol–gel derived materials
• Organic electronic materials, such as conjugated polymers and donor–acceptor blends

Because the technique is non-destructive and requires no conductive coating or sectioning, researchers can analyze samples directly on substrates such as silicon, glass, metals, or flexible films.

GISAXS and GIWAXS offer structural insight uniquely tailored to surface and thin-film materials:

Overall, these capabilities make GISAXS/GIWAXS indispensable tools for understanding how nanostructure formation at surfaces governs the performance of devices, coatings, and functional materials.