Graphene Synthesis on Silver Foil by Chemical Vapor Deposition Using Ethanol

We investigated the growth of graphene on silver surfaces by chemical vapor deposition (CVD) with ethanol as the gas material under various growth conditions. The investigation was based on Raman spectroscopy analysis. We determined that over 900°C is required to decompose the ethanol. Additionally, we proposed a graphene growth mechanism on the silver surfaces. Herein, the formation of the graphene nuclei and silver evaporation are competing processes, which limits the crystallinity of the graphene. Furthermore, we demonstrated that the addition of hydrogen during the CVD growth and the modifications of the conditions of the sample cooling process after the growth are valid for expanding the growth conditions and improving the crystallinity of graphene. The modifications included a low cooling rate of the substrates, maintenance of the environmental pressure equal to that of the growth, and a continuous supply of ethanol after the growth. The results indicate that the suppression of silver atom evaporation is the key to obtaining high-crystallinity graphene.