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 sp3 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).