Synthesis and characterization of c-BN films prepared by ion beam assisteddeposition and triode sputtering

Boron nitride films deposited on unheated c-Si substrates by ion beam assis ted deposition (IBAD) and triode sputtering (TS) techniques are studied. Th e composition, micro:structure and crystallinity of the films obtained by t he two techniques are compared The methods of characterization used in this study are: X-ray photo-electron, infrared, and Raman spectroscopies. High- resolution cross sectional TEM is used to confirm the optical results. In t he case of films prepared by IBAD, the ion energy was 350-500 eV. The films were prepared from different gas mixtures of nitrogen and argon, boron was supplied by evaporation of elemental boron. TS films were prepared with 10 0% of nitrogen, the boron was supplied by sputtering a pure boron target. T his study shows that, in comparison with TS samples, IBAD samples have high er chemical and physical stability. The par-tide-size dependence of frequen cies and damping of optical phonons is studied for all samples from the ana lysis of Raman scattering and infrared spectra. A very important difference between the particle-sizes of IBAD and TS samples is observed. A progressi ve chemical etching by nitric acid at 80 degrees C combined with infrared c haracterization was successfully performed on IBAD samples deposited at low ion flux and announces a mixture of sp(2) and sp(3) phases with high conte nt of sp(3) structure. All results are in full agreements with TEM results. (C) 1999 Elsevier Science S.A. All rights reserved.