Thickness dependent electronic structure of ultra-thin tetrahedral amorphous carbon (ta-C) films

► Filtered Cathodic Vacuum Arc deposited ultra-thin ta-C films (1-10 nm thick). ► CK-edge NEXAFS provides evidence of surface defects (C―H bonds). ► Concentration of C―H surface defects decreases with increasing thickness. ► π*CC behavior suggestive of rise and fall of sp2 bonding configuration. ► Critical thickness required for stability of sp3 distorted sp2 structures.