Multi-layer graphene obtained by high temperature carbon implantation into nickel films

We present a study of carbon implantation in a stacked layered substrate made of Ni(200 nm)/SiO2(300 nm)/Si(1 0 0). The carbon atoms have energy of 20 keV. Simultaneous or subsequent heat treatment is performed in the 450-600 °C range. The carbon dose was set to be 4 equivalent graphene monolayers (EGM). Most of the carbon implanted diffuses directly to the surface, forming multi-layer graphene (MLG). A progressive structuration of these graphitic fragments occurs with the increase of the implantation temperature. However, this structuration is more pronounced if the thermal treatment is performed in situ following the carbon implantation at room temperature. The mean MLG thickness, corresponding to around 4-5 EGM, was measured by angular X-ray Photoemission Spectroscopy. Moreover, the overall carbon concentration inside and at the limits of the nickel films, determined by nuclear reaction analysis (NRA), is in the 7-10 EGM range. This concentration depends on the temperature but it exceeds surprisingly the expected carbon concentration. This discrepancy shows that some carbon is incorporated along the different steps. NRA analyses of the preparation confirm this point. To obtain large film, the presented results stress the interest to better understand the full system carbon-nickel in the preparation of MLG at each step of the process.