Kumar Rakesh, Mehta B R
J Nanosci Nanotechnol. 2017 Jan;17(1):286-99. doi: 10.1166/jnn.2017.12594.
In this paper, a systematic and comprehensive study has been carried out to observe the effect of synthesis and transfer conditions on the quality and uniformity of graphene deposition in an atmospheric pressure chemical vapour deposition set up. It was observed that the quality of graphene was highly affected by the synthesis conditions, such as, synthesis temperature, synthesis duration, methane and hydrogen flow rate ratio and total flow rate during deposition and cooling cycles. The quality of graphene was observed to be significantly improved upon increasing the synthesis temperature while increase in methane and hydrogen flow rates beyond a particular limit resulted into degradation in the quality of graphene. From the comparison of scanning electron microscopy images of graphene grown at different times, it was found that the nucleation and growth of graphene domains strongly depend on the growth time. The process of transfer of monolayer graphene was significantly improved by controlling the PMMA concentration using a modified three step technique. Raman spectroscopy and the high mobility (˜8153 cm2V−1s−1) of graphene after transferred onto a SiO2/Si substrate confirm the high quality of monolayer graphene obtained by the optimizations of synthesis and transfer conditions in this study.
在本文中，开展了一项系统且全面的研究，以观察合成和转移条件对大气压化学气相沉积装置中石墨烯沉积质量和均匀性的影响。研究发现，石墨烯的质量受合成条件的影响很大，例如合成温度、合成持续时间、沉积和冷却循环期间甲烷与氢气流速比以及总流速。观察到，提高合成温度时石墨烯质量显著改善，而甲烷和氢气流速增加超过特定限度会导致石墨烯质量下降。通过比较不同时间生长的石墨烯的扫描电子显微镜图像发现，石墨烯畴的成核和生长强烈依赖于生长时间。采用改进的三步技术控制聚甲基丙烯酸甲酯（PMMA）浓度，显著改善了单层石墨烯的转移过程。转移到SiO₂/Si衬底上后，石墨烯的拉曼光谱和高迁移率（约8153 cm²V⁻¹s⁻¹）证实了本研究通过优化合成和转移条件获得了高质量的单层石墨烯。
