Preparation of hydrogenated tetrahedral amorphous carbon (ta-C:H) films with good mechanical properties by plasma-enhanced chemical vapor deposition (PECVD) is expected to meet requirement in industrial application. This paper reported the microstructure and mechanical properties of (ta-C:H) films prepared by a self-designed PECVD technique. As the bias voltage varies from –200 V to –500 V, the hardness and elastic modulus first decrease and then increase, reaching the maximum values of 34.0 GPa and 282.0 GPa respectively. The evolution of compressive stress with bias voltage shows a similar trend. In this case, the hardness and elastic modulus of films prepared by the self-designed PECVD technique both are improved, compared with those by the conventional PECVD methods. The mole fraction of sp³ hybridized bond is greater than 62.3% when the bias voltage changes from –200 V to –500 V. Carbon films were deposited using the self-designed PECVD technique, showing the typical characteristics of ta-C:H films. This can be attributed to the increased ion bombardment and ionization due to the incorporation of a water-cooled radio frequency double helix electrode and a plate electrode resulting in an enhanced sp³ content. This paper provides a promising technology to fabricate ta-C:H films with high hardness and elastic modulus for industrial applications.

The tetrahedral amorphous carbon (ta-C) films were fabricated by 45° double-bent filtered cathodic vacuum arc technique, and the wettability, surface energy, roughness, surface topography, friction coefficient and microstructure evolution of ultrathin ta-C film as functions of incident angles of carbon ions were investigated. The results reveal that as the incident angle of carbon ions increases from 0° to 60°, the water contact angle of films slightly increases from 77.6° to 82.4° and the glycerin contact angle of films slightly increases from 64.7° to 71.2°, indicating that all the films are hydrophilic. The total surface energy decreases from 33.9 mJ/m² to 28.0 mJ/m². The slight increase of observed contact angle is attributed to the decrease of surface energy and increase of surface roughness. Also, the average friction coefficient increases from 0.140 to 0.217. According to the near edge X-ray absorption fine structure data, little change for the hybridized sp³ bond content in the deposited ta-C films appears, regardless of the change of incident angle in a range of 0°–60°.