Selective graphene growth from DLC thin film patterned by focused-ion-beam chemical vapor deposition

The authors were able to grow a few-layer graphene film on a SiO2 substrate directly and selectively by using focused-ion-beam chemical vapor deposition (FIB-CVD) and a Ga evaporation process. FIB-CVD can control the thickness of the diamondlike carbon (DLC) film and potentially control the number of graphene layers, and Ga evaporation causes the direct transformation of patterned DLC into graphene. DLC was graphitized by annealing with a Ga film at 1000 °C and 1100 °C. Increasing the thickness of the Ga film resulted in a graphitized pattern that had a strong Raman 2D band. The formation of graphene above and around a dimple on the SiO2 layer indicates that Ga dissolved the DLC and graphene precipitated not between the liquid Ga and the SiO2 substrate but, rather, on the small droplets of Ga. This behavior is different than that reported in previous studies of graphitization at the interface between a carbon layer and liquid Ga.