Single-Layer Graphene Synthesis on a Al₂O₃(0001)/Cu(111) Template Using Chemical Vapor Deposition

The parameter space of graphene growth using chemical vapor deposition on an untwinned single-crystalline Al2O3(0001)/Cu(111) template is discussed. The influence of growth temperature, methane flow and carbon dose is examined to assess graphene quality and multilayer coverage. An optimized growth window is identified yielding single-layer graphene. Production temperatures above 850°C result in a graphene quality improvement, but also an increase in multilayer coverage. Adapting graphene dosages by minimizing the growth time is the key element to reduce the amount of multilayer domains without affecting the quality. After graphene transfer, the multilayer graphene areas show a large increase in I2D/IG peak ratio, which indicates a turbostratic stacking order of graphene multilayer domains. Two growth models are put forward, i.e. a carbon penetration mechanism and an adsorption-diffusion mechanism.