Fourier transform infrared spectroscopy analysis of thin boron nitride films prepared by ion beam assisted deposition

Thin boron nitride (BN) films were synthesized by ion beam assisted deposition (IBAD). From Fourier transform infrared spectroscopy (FTIR) analysis results, it was found that: the films with the co-presence of explosion-phase BN (E-BN) and sp2-bonded hexagonal BN (h-BN), and those with pure h-BN were formed in the respective substrate temperature regions of 20–85 °C and 350–400 °C, under nitrogen ion irradiation (ion energy from 500 to 1000 eV), while the substrate temperature at 400 °C and mixed nitrogen and argon ion irradiation were necessary for the formation of sp3-bonded cubic BN (c-BN). To our knowledge, the E-BN phase was formed firstly by IBAD in this study. The crystalline phase identification through the FTIR results was in line with X-ray diffraction results. The shift of the c-BN peak position is usually attributed to remaining compressive stress in the film. In this work, the downward shift of the c-BN peak position and the broadening of the c-BN peak, which were observed when the film thickness increased, can be interpreted using a phenomenological description of structural disordering in the c-BN sites. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)