Infrared and Raman analysis of plasma CVD boron nitride thin films

We present an optical investigation, by means of polarized IR reflectivity and Raman scattering, of the quality and stability of PECVD grown BN films obtained on the anode and on the cathode of a parallel-plate radio-frequency reactor by glow discharge decomposition of two different gas mixtures, B2H6-H2-NH3 and B2H6-N2. The addition of Ar to B2H6-N2 has also been investigated. It is shown that polarized IR reflection spectra of thin films have a complex optical behaviour, which is a function of the oblique angle of incidence and the substrate material used in the deposit. However, these spectra are predictable when optical theory is applied. The results obtained show the capabilities of polarized IR reflection and Raman scattering to perform detailed investigations on the microstructure and aging of BN thin films, independently of the substrate material.