Effects of titanium and aluminum incorporations on the structure of boron nitride thin films

Boron nitride (BN) based composite thin films have been prepared by ion beam assisted deposition (IBAD) employing two electron beam evaporators. 3~5 at.% either Ti or Al was incorporated into the BN composite films. Fourier transform infrared (FTIR) spectroscopy was used for phase identification of the BN composite films. The influences of the Ti and Al additions on the cubic phase formation in the BN films are reported. It has been found that the Al incorporation has a strong negative effect on cubic BN (cBN) formation. No cubic phase can be obtained under the presently chosen ion-bombardment parameters. However, the disturbance of 3~5at.% Ti addition depending on the preparation conditions for the BN thin films, only shifts the threshold of ion/atom ratio of the IBAD process which is required for cBN formation to a higher value. In order to understand the different behaviors of the Ti and Al incorporations, the chemical states of the Ti and Al additions in the BN composite films were examined by X-ray photoelectron spectroscopy (XPS), indicating preferential formation of TiB2 and AlN, respectively.