X-Ray Analysis – Diffraction / Reflectivity

X-ray analysis techniques are used to look at crystallographic structures of materials like powders or films deposited on substrates. Diffraction peaks are produced by constructive interference when the beam is scattered at specific angles from each set of lattice planes within the crystal.  The X-ray diffraction pattern is the fingerprint of periodic atomic arrangements in a given material.  An on-line search of a standard database enables quick phase identification for a large variety of crystalline samples.  XRD provides information on structures, phases, preferred crystal orientations (texture) and other structural parameters such as average grain size, crystallinity, strain and crystal defects.

Another X-ray analysis called X-ray Reflectivity or XRR is used to measure thin films on a substrate.  In this analysis the X-ray beam bounces off the film surface and the reflected beam analyzed to determine film thickness, interfacial roughness and density.  The technique is useful for films ranging from 20 Å to 1 mm total thickness. Films can be single or multilayer structures, and the thickness of individual layers can be determined in minutes, with no optical constant corrections required. XRR works for films that are epitaxial, polycrystalline or amorphous.

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