Modification of optical and mechanical properties of nitrogen doped diamond-like carbon layers

Abstract

We have deposited diamond-like carbon (DLC) films on glass and Si substrates with direct ion beam deposition technique and investigated the effect of N2 doping on their structural, mechanical, and optical properties. The DLC coatings were doped with nitrogen under different flow rates of 5, 10, 20, 40, and 50 sccm. Morphological characteristics investigation of the prepared samples showed decrement in their average roughness from 4.1 to 0.68 nm. Raman studies showed that the number of graphitic sp2 bonding increased with N doping. By increasing the N2 content, the graphite cluster size increased. FTIR measurement revealed the functional groups available in the prepared samples. UV–Vis analysis showed that the optical transmission of nitrogen-doped DLC (N-DLC) coatings decreased when N2 content increased from 5 to 40 sccm followed by decrement in both the optical band gap and the internal stress. Finally, the mechanical properties such as hardness and elastic modulus decreased by increasing N2 content from 5 to 40 sccm.