MIXED PHASE NANOCRYSTALLINE BORON-NITRIDE FILMS - PREPARATION AND CHARACTERIZATION

BN films have been deposited by the technique of magnetron sputtering from a BN target at bias voltages between 0 and 100 V and temperatures of 100-degrees-C and 500-degrees-C on silicon, glass and steel substrates. The films were investigated by scanning and transmission electron microscopy, IR spectrometry and glancing angle X-ray diffraction. All films exhibited "amorphous-like" diffraction patterns with line widths of several degrees typical for grain sizes in the nanometric range. The measured patterns were compared with computer-generated patterns assuming various structures, crystal sizes and shapes. Best agreement was obtained assuming a mixed phase model of cubic and hexagonal (graphitic) BN with grains consisting of 50-1000 atoms. Structure and grain size of the films were sensitive to bias voltage and deposition temperature. The IR transmission spectra obtained with our films reflected roughly the characteristics of hexagonal BN. However, the presence of cubir or wurtzite BN was indicated by a depression in the spectrum at about 1080 cm-1. All films exhibited high transmission up to about 200 nm in the near-UV region. Adhesion on steel substrates was strongly dependent on the deposition temperature.