Study of graphene layer growth on dielectric substrate in microwave plasma torch at atmospheric pressure
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| Year of publication | 2019 |
| Type | Conference abstract |
| MU Faculty or unit | |
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| Description | Ethanol decomposition in microwave plasma represents simple and environmentally friendly way of graphene production in the gas phase. In this work we study formation of graphene layer on the dielectric substrate Si/SiO2 placed in the vicinity of the discharge. Microwave plasma torch (2.45 GHz, 200-1000 W) at atmospheric pressure was used to study graphene layer deposition in Ar (250-1000 sccm) and ethanol (1-5 sccm) mixture. We used dual channel configuration of nozzle electrode with central Ar flow and precursor/Ar flow in secondary channel. The homogeneity and quality of graphene layer was investigated in dependence on substrate temperature (700-1000 K) and precursor flow. Samples were analyzed by SEM, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). SEM analysis of the silicon oxide substrate revealed presence of several nm large graphene crystals and larger, 100 nm and larger, graphene flakes. The size and distribution of the graphene nanocrystals varied with substrate temperature and precursor flowrate. By increasing ethanol flowrate, the size of the crystals increased and the number of larger flakes, formed in the gas phase, increased as well. Raman spectroscopy of layers showed presence of D (1350 cm-1), G (~ 1580 cm -1) and 2D (2690 cm -1) peaks with large I2D/IG ratio as can be seen in Fig.1. The XPS analysis and fitting of C1s peak showed small sp3/sp2 carbon bond ratio, below 10 %, in the deposited layers. In conclusion, microwave plasma at atmospheric pressure was successfully used for growth of graphene layer on dielectric substrate but the quality of the layer is lower in comparison with CVD deposited layers. |
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