Structural and mechanical properties of diamond-like carbon films deposited by an anode layer source

An anode layer source is a special ion gun, which can be fed with carbon precursors like acetylene to deposit hard and highly defect-free hydrogenated diamond-like carbon films at room temperature. The present study focuses on the influence of the process parameters - discharge voltage, process pressure and acetylene flow on structure and mechanical properties of the deposited films. Raman spectra show that an increased discharge voltage yields decreased structural disorder, i.e. a lower C-C sp(3) hybridised fraction of carbon atoms in the films. By an elevation of the discharge voltage from 1 to 3 kV the full width at half maximum of the G-band decreases from 194 +/- 0.2 cm(-1) to 183 +/- 0.7 cm(-1). Films deposited at the lowest discharge voltage show in accordance to the spectroscopic data the highest nanohardness (36 +/- 1 GPa), stress (-2.34 +/- 0.2 GPa) and reduced elastic modulus (180 +/- 4 GPa). (C) 2009 Elsevier B.V. All rights reserved.