  B and N K-edge x-ray absorption spectroscopy measurements have been performed
on three BN thin films grown on Si substrates using ion-assisted pulsed laser
deposition. Comparison of the films' spectra to those of several single-phase
BN powder standards shows that the films consist primarily of $sp^2$ bonds.
Other features in the films' spectra suggest the presence of secondary phases,
possibly cubic or rhombohedral BN. Films grown at higher deposition rates and
higher ion-beam voltages are found to be more disordered, in agreement with
previous work.
