Fabrication and characterization of superconducting MgB2 thin film on graphene

The building of superconductor/graphene hybrid structure has attracted a lot of attention in recent years as it provides an exciting platform to study the novel superconducting proximity effect in graphene and has promise in potential device applications. Here we report an experimental investigation on the fabrication of MgB2/graphene bilayer films. The fabrication process consists of two major steps: the transfer of monolayer graphene grown on copper foil to the target substrate, and then the deposition of MgB2 thin film on transferred graphene with a hybrid physical-chemical vapor deposition technique. The obtained MgB2 film on graphene shows a continuous film surface with prevailing c-axis orientation, and displays a narrow superconducting transition with high transition temperature Tc at 36 K, close to the value of 39 K in bulk MgB2. The decent crystalline property and high Tc of the film demonstrate the effectiveness of the present method in producing the MgB2/graphene hybrid structure, which lays a foundation for further exploring the proximity effect in graphene and developing related superconducting devices such as the Josephson junctions to work at relatively high temperatures.