Department of Chemistry, Rice University, 6100 Main Street, Houston, Texas 77005, USA.
ACS Nano. 2012 Oct 23;6(10):9110-7. doi: 10.1021/nn303352k. Epub 2012 Sep 19.
In this research, we constructed a controlled chamber pressure CVD (CP-CVD) system to manipulate graphene's domain sizes and shapes. Using this system, we synthesized large (~4.5 mm(2)) single-crystal hexagonal monolayer graphene domains on commercial polycrystalline Cu foils (99.8% purity), indicating its potential feasibility on a large scale at low cost. The as-synthesized graphene had a mobility of positive charge carriers of ~11,000 cm(2) V(-1) s(-1) on a SiO(2)/Si substrate at room temperature, suggesting its comparable quality to that of exfoliated graphene. The growth mechanism of Cu-based graphene was explored by studying the influence of varied growth parameters on graphene domain sizes. Cu pretreatments, electrochemical polishing, and high-pressure annealing are shown to be critical for suppressing graphene nucleation site density. A pressure of 108 Torr was the optimal chamber pressure for the synthesis of large single-crystal monolayer graphene. The synthesis of one graphene seed was achieved on centimeter-sized Cu foils by optimizing the flow rate ratio of H(2)/CH(4). This work should provide clear guidelines for the large-scale synthesis of wafer-scale single-crystal graphene, which is essential for the optimized graphene device fabrication.
在这项研究中，我们构建了一个受控腔室压力 CVD（CP-CVD）系统来操控石墨烯的畴尺寸和形状。使用该系统，我们在商业多晶 Cu 箔（99.8%纯度）上合成了大尺寸（~4.5mm²）的单晶六方单层石墨烯畴，表明其在低成本下具有大规模潜在的可行性。在室温下，在 SiO2/Si 衬底上，合成的石墨烯的正载流子迁移率约为 11000cm2V-1s-1，表明其质量可与剥离石墨烯相媲美。通过研究不同生长参数对石墨烯畴尺寸的影响，探讨了基于 Cu 的石墨烯的生长机制。Cu 预处理、电化学抛光和高压退火被证明对于抑制石墨烯成核位点密度至关重要。对于合成大单晶单层石墨烯，108Torr 的腔室压力是最佳的。通过优化 H2/CH4 的流速比，在厘米级 Cu 箔上实现了一个石墨烯种子的合成。这项工作应为大规模合成晶圆级单晶石墨烯提供明确的指导，这对于优化的石墨烯器件制造至关重要。
