Graphitization of self-assembled monolayers using patterned nickel-copper layers

Controlling the optical and electrical properties of graphene is of great importance because it is directly related to commercialization of graphene-based electronic and optoelectronic devices. The development of a spatially controlled layer-tunable and direct growth method is a favored strategy because it allows for the manipulation of the optical and electrical properties of graphene without complex processes. Here, patterned Ni on Cu layers is employed to achieve spatially thickness-tuned graphene because its thickness depends on the carbon solubility of catalytic metals. Transfer-free graphene is directly grown on an arbitrary target substrate by using self-assembled monolayers as the carbon source. The optical transmittance at a wavelength of 550 nm and the sheet resistance of graphene are adjusted from 65.0% and 2.33 kΩ/□ to 85.8% and 7.98 kΩ/□, respectively. Ambipolar behavior with a hole carrier mobility of 3.4 cm²/(V·s) is obtained from the fabricated device. Therefore, a spatially controlled layer-tunable and transfer-free growth method can be used to realize advanced designs for graphene-based optical and electrical devices.