Graphene Growth on Ge(110) Using a Photoresist as a Solid Carbon Source

We investigated the growth of graphene on a Ge(110) substrate using photoresist as the source of the solid material. First, we elucidated that a substrate temperature of 900°C was suitable for graphene growth. Subsequently, graphene was grown on the Ge surfaces under various conditions: we found that the optimal heating time was 3 min, and that the addition of hydrogen to the ambient gas flow improved the crystallinity of the graphene. Furthermore, we found that methoxybutyl acetate was a more suitable solvent for diluting the photoresist than acetone, as the resulting resist thin film exhibited less roughness before heating, which improved graphene crystallinity. Finally, from examining the effect of the flow rate of the mixture gas of Ar and H2, a drastic change in the graphene surface morphology was observed, which resulted from the mass transport of an extremely large amount of the substrate material. This phenomenon might have limited the crystallinity of the graphene and, therefore, should be suppressed in order to grow high-quality graphene using this method.