Solid phase growth of graphene on silicon carbide by nickel silicidation: graphene formation mechanisms

This work presents experimental evidence of the formation mechanisms of few-layer graphene (FLG) films on SiC by nickel silicidation. FLG is formed by annealing of a 40 nm thick Ni layer on 6H-SiC at 1035°C for 60 s, resulting in a Ni₂Si layer which may be capped by any Ni that did not react during annealing. It has been proposed that FLG forms on top of the Ni during the high temperature stage. In contrast, during cooling, carbon atoms which were released during the silicidation reaction may diffuse back towards the Ni₂Si/SiC interface to form a second FLG film. After annealing, layer-by-layer de-processing was carried out in order to unequivocally identify the FLG at each location using atomic force microscopy (AFM) and Raman spectroscopy.