X-ray absorption studies on cubic boron nitride thin films

Abstract

Cubic boron nitride (c-BN) films synthesized by various energetic species assisted physical vapor deposition and chemical vapor deposition techniques on Si and diamond-coated Si substrates have been investigated by boron and nitrogen K-edge angle-resolved x-ray absorption near-edge structure in both total electron yield and fluorescence yield modes. X-ray absorption spectrum has been developed to study the film structure, the quantity and distribution of the partially ordered turbostratic (t-BN) and amorphous (a-BN) sp2-hybridized BN phases, and the t-BN∕a-BN ratios. The preferred direction of the t-BN basal planes at the interface between c-BN and substrate is found to be normal or nearly normal to the substrate. The content of the sp2-bonded BN in the c-BN films deposited on diamond-coated Si substrates reduces remarkably. The modifications of the electronic structure of the c-BN films with respect to bulk hexagonal BN and c-BN have been investigated and the crystallinity of c-BN films has also been evaluated from the x-ray absorption near edge structure results.