Modulation of annealing process for the direct growth of multi-layered graphene on diamond with high uniformity

In this paper, graphene with good uniformity was successfully grown on (100)-orientation single crystal diamond substrate directly by regulating the annealing and cooling temperature. A medium annealing temperature of 1000 °C and duration of 20 s can trade-off the thickness and uniformity. In addition, the stress condition and thickness of graphene also present a dependence on cooling temperature. Under the cooling temperature of 500 °C, the multi-layered graphene (30 nm thickness) with high mobility (737 cm2/Vs at room temperature) was obtained. The surface roughness was 2.36 nm for the graphene layer and 0.85 nm for the etched diamond substrate, indicating a good surface flatness. By comparing with the Ti/Au electrode, it was found that the graphene directly synthesized on diamond presented better ohmic contact with the diamond substrate.