摘要
Graphene samples with different morphologies were fabricated on the inside of copper enclosures by low pressure chemical vapor deposition and tuning the flow rate of hydrogen. It is found that the flow rate of hydrogen greatly influences the growth of graphene. Ther-modynamic analysis indicates that a higher flow rate of hydrogen is favorable to the formation of good quality graphene with regular mor-phology. However, the mass-transfer process of methane dominates the growth driving force. At very low pressure, mass-transfer proceeds by Knudsen diffusion, and the mass-transfer flux of methane decreases as the flow rate of hydrogen increases, leading to a decrease in the growth driving force. At a higher pressure, mass-transfer proceeds by Fick＇s diffusion, and the mass-transfer flux of methane is dominated by the gas velocity, whose variation determines the growth driving force variation of graphene.
Graphene samples with different morphologies were fabricated on the inside of copper enclosures by low pressure chemical vapor deposition and tuning the flow rate of hydrogen. It is found that the flow rate of hydrogen greatly influences the growth of graphene. Ther-modynamic analysis indicates that a higher flow rate of hydrogen is favorable to the formation of good quality graphene with regular mor-phology. However, the mass-transfer process of methane dominates the growth driving force. At very low pressure, mass-transfer proceeds by Knudsen diffusion, and the mass-transfer flux of methane decreases as the flow rate of hydrogen increases, leading to a decrease in the growth driving force. At a higher pressure, mass-transfer proceeds by Fick＇s diffusion, and the mass-transfer flux of methane is dominated by the gas velocity, whose variation determines the growth driving force variation of graphene.
基金
supported by the Postdoctoral Science Foundation Funded Project(No.2012M521743)
the Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2012JM8009)
the Doctoral Program Foundation of the Institutions of Higher Education of China (No.20110203120014)
the Fundamental Research Funds for the Central Universities(No.K50510250005)
the Applied Materials Innovation Fund of Xi'an(XA-AM-201002)
the Fundamental Research Funds for the Central Universities(No.JB141108)
