Thin Film Analysis

Epitaxial lattice parameter measurements

X-ray diffraction is especially valuable to the study of epitaxial layers and other thin film materials. Using precision lattice parameter measurement methods, the lattice mismatch of an epitaxial layer and its substrate can be determined with great precision. This lattice parameter match or mismatch is an important factor in epitaxial devices such as magnetic garnet films for bubble memories, doped gallium arsenide films for LED and high-speed transistors, infra-red detectors and other important electronic products. Another interesting use of XRD for thin films is that the coefficient of thermal expansion can be determined by plotting lattice parameters versus temperature using a high temperature diffractometer.

High-resolution X-ray rocking curves are often used to determine precisely the composition and thickness of epitaxial alloy films. Rigaku's SmartLab diffractometer, which offers variable resolution optics, is ideal for such purposes. The modular design of the SmartLab optics allows users to easily insert different optical elements of their choice, such as Ge(220)x2, Ge(220)x4, Ge(400)x2, or Ge(440)x4 monochromators for the incident beam and a Ge(220)x2 analyzer for the diffracted beam. These optic modules can be automatically detected by the controlling computer and are aligned automatically. An automatic variable receiving slit is also available for the diffracted beam.