X-ray diffraction analysis on polycrystalline or epitaxial thin films - Use of a sample holder in asymmetric reflectance mode and equipped with a curved-position sensitive detector

We have realised an X-ray diffraction apparatus with a four-axis sample hol der working under controlled incidence in the reflection mode. The incident beam, supplied by a rotating anode associated with a Bartels monochromator , is strictly parallel and monochromatic. The diffracted beams were simulta neously measured using a curved position sensitive detector. The use of thi s diffractometer in powder diffraction experiments has been presented elsew here. In this paper we would illustrate the possibility of such an apparatu s in the field of thin film characterization. Thin films of zirconia precursor were formed on mirror-polished sapphire wa fers by a sol gel dip coating process. Thermal treatment of the sample at m oderated temperature induced the crystallisation of zirconia under the tetr agonal form. The coating is made of randomly oriented nanocrystals. Higher temperature thermal treatment resulted in the formation of micrometer sized islands epitaxied onto the single crystalline substrate. The relative diso rientation of those islands was estimated through rocking-curves measuremen ts. Sometimes the diffracted intensity distributions of the different islan d families were partially superimposed on each others. The measurement of a ll the intensity distributions obtained by the use of the curved detector a llowed us to separate the rocking curves of each islands family.