Mechanical properties of amorphous boron carbon nitride films produced by dual gun sputtering

Mechanical properties and bonding characterisation of amorphous boron carbon nitride (a-BC_xN_y) films prepared by dual gun sputtering system was studied. The a-BC_xN_y films deposited at different temperatures and having different carbon concentrations revealed that at lower deposition temperatures (≤200 °C), carbon contents in the range of ∼25 at.% produced the harder films where the hardness and elastic modulus were found to be 12.5 and ∼150 GPa, respectively. For higher deposition temperatures (≥400 °C), carbon content in the range of 40 at.% produced the harder films. The chemical composition and phase identification were done collectively by X-ray photoelectron spectroscopy and Auger electron spectroscopy. Fourier transform infrared spectroscopy was used to analyse the hybridisation levels of the constituent elements and to show the evolution of different phases in the a-BC_xN_y network. The low hardness levels were attributed to the unfavourable C(sp)-N bonding configuration in the network, a possible phase separation and high oxygen contents (∼10 at.%) in the film.