| Summary: | 碩士 === 國立臺灣大學 === 物理研究所 === 102 === Methyl group (CH3&;#903;) is an important intermediate specie in the growth of graphene when using hydrocarbon as precursors. In this work, we demonstrate a one-shot synthesis method of high-quality nitrogen-doped graphene on copper substrates by using methyl from pyrolysis of azomethane, and discuss an observation about the growth of graphene. Pyrolysis of azomethane gas at ~1000oC generates mainly methyl, methylnitrene, nitrogen and a few other minor species. We discovered that, with methyl, graphene can readily grow at a low temperature of 600~700°C with a high probability, on all major Cu orientations. Though the islands’ shape and nucleation density of graphene are affected by the crystal orientations, graphene has a uniform growing rate on Cu(111), Cu(110) and Cu(100). Nitrogen doping density with N/C ratio of ~ 0.05% is observed. The dopants are generated due to the incorporation of methylnitrene during growth. Though having a low doping density, evidence shows that the synthesis of highly doped graphene can be achieved. Furthermore, when using methyl group as precursor, a “copper etching effect” is observed. Graphene islands are discovered to be capable to “dig a hole” on copper surface. We surmise that this is due to the reaction between copper atoms and methyl which forms intermediate species such as CHx-Cu. Thus, copper atoms at surface can be carried away in this structure.
|
|---|
