Single-Crystal Antimonene Films Prepared by Molecular Beam Epitaxy: Selective Growth and Contact Resistance Reduction of the 2D Material Heterostructure.

Single-crystal antimonene flakes are observed on sapphire substrates after the postgrowth annealing procedure of amorphous antimony (Sb) droplets prepared by using molecular beam epitaxy at room temperature. The large wetting angles of the antimonene flakes to the sapphire substrate suggest that an alternate substrate should be adopted to obtain a continuous antimonene film. By using a bilayer MoS/sapphire sample as the new substrate, a continuous and single-crystal antimonene film is obtained at a low growth temperature of 200 °C. The results are consistent with the theoretical prediction of the lower interface energy between antimonene and MoS. The different interface energies of antimonene between sapphire and MoS surfaces lead to the selective growth of antimonene only atop MoS surfaces on a prepatterned MoS/sapphire substrate. With similar sheet resistance to graphene, it is possible to use antimonene as the contact metal of 2D material devices. Compared with Au/Ti electrodes, a specific contact resistance reduction up to 3 orders of magnitude is observed by using the multilayer antimonene as the contact metal to MoS. The lower contact resistance, the lower growth temperature, and the preferential growth to other 2D materials have made antimonene a promising candidate as the contact metal for 2D material devices.