Cubic boron nitride formation on Si (100) substrates at room temperature by pulsed laser deposition

We are studying the boron nitride system by using a pulsed excimer laser to ablate from hexagonal BN(hBN) targets to form BN films. We have deposited BN films on heated (600 °C) and room-temperature silicon (100) surface in an ambient background gas of N2. Fourier transform infrared (FTIR) reflection spectroscopy indicates that the films grown at high temperature have short-range sp2 (hexagonal-like) order, whereas films grown at room temperature are a mixture of sp3-bonded BN and sp2-bonded BN. Electron diffraction confirms the presence of cubic BN (cBN) material in the films grown at low temperature and the corresponding TEM lattice images show a grain size of ∼200 Å. The presence of cBN in the films correlates with laser energy density, with cubic material appearing around 2.4 mJ/cm2. Auger electron spectroscopy (AES) indicates that the films are nitrogen deficient.