Substrate surface effect on the structure of cubic BN thin films from synchrotron-based X-ray diffraction and reflection

Cubic BN (cBN) thin films prepared by mass-selected ion beam deposition technique (MSIBD) on Si substrates with different surface roughness were studied by synchrotron-based grazing incidence X-ray diffraction (GI-XRD) and X-ray reflectivity (XRR) measurements. The BN films are mostly composed of two phases. One is cBN phase, the other is hexagonal BN (hBN) phase. The cubic phase content of the thin films is dependent on the roughness of their corresponding substrates. The smooth substrate surface is helpful for the nucleation of the cBN phase. cBN phase is mostly grown in the near surface region of the films and there is a hBN interlayer at the film–substrate interface. GIXRD and XRR are proved to be powerful tools for analyzing the structure of the cBN thin films.