Adhesion and bonding of polar and non-polar SiC surfaces to Ti(0001)

Abstract

The atom superposition and electron delocalization molecular orbital calculations have been performed for studying the interfacial bonding and adhesion of some polar and nonpolar surfaces of α- and β-SiC with the close-packed Ti(0001) surface, using large cluster models and idealized structures. Polar SiC surfaces studied in this work are the Si- and C-terminated (111) and (100) planes and the nonpolar surfaces with equal concentration of Si and C, i.e., β-SiC(110), α-SiC(101̄0) and α-SiC(112̄0). For the unrelaxed polar SiC surfaces, the average Si/Ti and C/Ti interfacial bond strengths are maximum for the β-SiC(110)/Ti(0001) interface due to two dangling surface state orbitals on each surface atom in place of one on the (111) SiC surfaces. The Si- and C-terminated (100) surfaces undergo dimerization. Adhesion energies for the (111) and (100) surfaces to Ti(0001) are comparable when surface relaxation and reconstruction effects are considered. Nonpolar α- and β-SiC surfaces bind comparatively weakly to titanium, and their adhesion energies to Ti(0001) are all approximately equal. In each case of interfacial bonding the sp hybridized dangling orbitals on Si and C surface atoms are stabilized by bond formation with Ti 3d band orbitals.