Background
The figure below shows the measured pole figure of a 170 nm thick AlN thin film epitaxially grown on c-sapphire substrate using Rigaku's SmartLab® high-resolution diffraction system. The three-fold green spots on the red circle arise from the sapphire substrate, while the six-fold blue spots are reflections from the AlN film.
Thin films grown by physical or chemical deposition techniques often exhibit textured structures, which are responsible for their anisotropic physical properties. X-ray pole figure analysis is able to provide quantitative information of the texture of the thin films as well as the epitaxial relation between the films and the substrates.
From the pole figure below, the crystal unit cell of AlN is rotated 30° with respect to that of the sapphire substrate, as shown below. Moreover, the AlN film is seen to be highly oriented, with an out-of-plane tilt and an in-plane twist less than 0.5°.
