title: Studying the growth of cubic boron nitride on amorphous tetrahedral carbon interlayers.
abstract: The growth of cubic boron nitride (cBN) films on bare silicon and amorphous tetrahedral carbon (ta-C) layers prepared on silicon substrates was studied. The cBN films were prepared by radio frequency magnetron sputter deposition at approximately 870 degrees C. The original ta-C interlayers were graphitized and restructured under high temperature and possibly under ion bombardment during BN deposition. The majority of graphitic basal planes were nearly perpendicular to the surface of silicon substrates. The BN films grown on these restructured carbon layers were deposited with higher content of cubic phase and did not show delamination signs. Turbostratic BN (tBN) basal planes extended carbon basal planes and their edges served as cBN nucleation sites. The cBN films grown on textured ta-C interlayers were insensitive to the ambient environment. The residual sp(3)-bonded carbon phase confined in the interlayers probably acts as a diffusion barrier preventing the oxidation of dangling bonds near BN interface and thus precludes weakening the interface as a result of volume expansion. The carbon interlayers also improve the crystallinity of the oriented tBN because they are continuation of carbon graphitic basal planes so that the volume fraction of nitrogen-void (N-void) defects in the sp(2)-bonded BN intermediate layers is reduced. The strong sp(3)-bonded carbon matrix could thereto withstand large compressive stress and facilitates deposition of thicker cBN films.
authors.affiliation: Center Of Super-Diamond and Advanced Films (COSDAF) & Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.
authors.forename: Kar Man
authors.initials: KM
authors.lastname: Leung
authors.forename: Chit Yiu
authors.initials: CY
authors.lastname: Chan
authors.forename: Yat Ming
authors.initials: YM
authors.lastname: Chong
authors.forename: Yuen
authors.initials: Y
authors.lastname: Yao
authors.forename: Kwok Leung
authors.initials: KL
authors.lastname: Ma
authors.forename: Igor
authors.initials: I
authors.lastname: Bello
authors.forename: Wen Jun
authors.initials: WJ
authors.lastname: Zhang
authors.forename: Shuit Tong
authors.initials: ST
authors.lastname: Lee