Laser interference induced nano-crystallized surface swellings of amorphous carbon for advanced micro tribology

We have investigated the direct laser interference patterning (DLIP) of tetrahedral amorphous carbon (ta-C) thin films in the nanometer region. In this paper we achieved texturing of ta-C from a surface swelling either by a phase change from sp3 to sp2 or thin film delamination. In contrast to surface ablation, the thin film is not removed from the silicon surface. With this technique a surface nano-swelling of ta-C with an area-speed of 1 m2 min−1 and nanometric resolution can be realized. The phase changes in the ta-C, due to DLIP material heating are undermined by thermal simulations of the patterning process. Additionally we investigated for the first time the influence of periodic nano-swelling on the coefficient of friction (COF). The COF of periodic graphitized surfaces was found to be lower (~50%) compared to as grown ta-C. This reduction of the COF can be attributed to a reduced area of contact.