Trace Oxygen-Assisted Synthesis of High-Quality Graphene with Improved Electrical Performance

Point defects and amorphous carbon contamination, which are almost inevitable during the high-temperature chemical vapor deposition growth process, are demonstrated to severely degrade the intrinsic properties of graphene films, particularly their electronic performance. This study puts forward a trace oxygen-assisted strategy for synthesizing high-quality graphene by effectively eradicating amorphous carbon contamination and then promoting the repair of underlying lattice defects. Both experimental results and first-principles calculations reveal that lattice healing is inhibited when the lattice is covered by amorphous carbon but facilitated with the aid of oxygen. The high crystallinity of the synthesized graphene is evidenced by its strong resistance to electron-beam radiation and mechanical property (2D Young's modulus ≈355 N m^-1 and fracture strength ≈1778 nN) comparable to that of exfoliated graphene. Furthermore, the as-obtained graphene film exhibits enhanced electronic performance, including a low sheet resistance of 174.4 ± 31.9 Ω sq^-1 and a high carrier mobility exceeding 15 000 cm² V^-1 s^-1 at room temperature. This work not only elucidates the novel functions of oxygen in the synthesis of high-quality graphene but also offers new prospects for further enhancing the performance of graphene.