Composition and bonding structure of boron nitride B1−xNx thin films grown by ion-beam assisted evaporation

We present a detailed study of B1−xNx (0 < x < 0.6) films synthesized at room temperature by N 2 + ion-beam assisted evaporation of boron. The atom–ion ratio was related to the final boron concentration as determined by X-ray energy dispersive spectroscopy (XEDS), and to the bonding structure explored by infrared (IR) and X-ray absorption near-edge structure (XANES) spectroscopies. IR and XANES revealed that N-rich boron nitrides had a graphite-like structure with embedded nitrogen molecules, while B-rich boron nitrides consisted of different ratios of B13N2/h-BN phases. Our spectroscopic results indicate that this B13N2 structure is made of B12 icosahedral units linked by N–B–N linear chains.