Oxygen‐Dependent Synthesis of Graphene on γ‐Alumina Catalyst

Gamma‐alumina (γ‐Al₂O₃) is one of the most promising ceramic catalysts for the graphene growth due to its weak bonding with graphene guaranteeing excellent detachability of graphene grown on it and its use as a dielectric layer for graphene‐based electronic devices. Oxygen leakage in graphene growth by chemical vapor deposition (CVD) process is unavoidable resulting in deteriorated graphene quality and device performance. This paper elucidates the role of oxygen on the growth of graphene on γ‐Al₂O₃ quantitatively and systematically. Escaping from unreliable analysis of the oxygen concentration in the CVD tube during the process, this paper directly focuses on the oxygen contents in resultant graphene crystals grown at diversified positions along the tube displaying from 9.75% to 14.82%. Oxygen‐dependent electrical properties of the graphene‐based electrical devices including sheet resistance, contact resistance, and electrical homogeneity are measured to 0.82–6.64 kΩ sq⁻¹, 0.50–4.43 kΩ mm, and 23.0–97.9%, respectively, with the sp² densities ranging from 51.0% to 72.1%.