| Summary: | 碩士 === 國立中央大學 === 物理學系 === 107 === As the one of the promising method for graphene growth, chemical vapor deposition (CVD) features the low cost, wafer-scaled graphene layer production. However, the temperature for graphene growth is about 1050℃ which has the problem of energy consumption. The development of plasma enhanced chemical vapor deposition (PECVD) eases the problem. High energy ions and electrons in plasma replace the thermal energy and reduce the needed temperature to about 500-900℃. While, the CVD graphene is limited by its polycrystalline grain which contains many grain boundary and reduce the quality of graphene. Therefore, the pursuit for the large grain size graphene is the important issue. For this purpose, the understanding of growth dynamics of graphene is needed for the controlling of the quality of graphene.
In our works, we demonstrate the quick, low power growth process of fully-covered graphene on copper foil by direct capacitive-coupled plasma ratio frequency plasma enhanced chemical vapor deposition (CCP-RF-PECVD) system under low pressure. In addition, the study of nucleation and growth dynamics with different ratio of hydrogen and methane is revealed. By tuning the flow rate of hydrogen, the growth dynamics of graphene is determined by the competition of activation and etching effect of hydrogen. After the characteristic of graphene by SEM and image analysis by Imagej, the growth dynamics is quantified and explained by Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. In low H2 flow rate, nucleation in early stage and high nucleation rate supplies the high growth rate. While in high H2 flow rate, the diffusion of precursor on the substrate surface and epitaxial growth dominated and produced the bigger grain. Furthermore, the simulation of modified JMAK model which considered etching effect of H plasma fits well for experiment data. The dispersive kinetics of growth dynamics has been revealed and further understood.
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