Enhancement of sp(3)-bonding in high-bias-voltage grown diamond-like carbon thin films studied by x-ray absorption and photoemission spectroscopy

X-ray absorption near-edge structure (XANES) and valence- band photoemission spectroscopy (VB-PES) were used to elucidate the electronic and mechanical properties of diamond-like carbon (DLC) thin films deposited by the plasma-enhanced chemical vapour deposition method at various bias voltages (V-b) using a C2H2 vapour precursor in an Ar+ atmosphere. The increase of V-b is found to increase and decrease the contents of sp(3)- and sp(2)- bonded carbon atoms, respectively, i.e. the films become more diamond-like. The Young's modulus measurements show increases with the increase of the presence of sp3-bonded carbon atoms in the structure of the DLC films.