Method of pre-treating substrate and method of directly forming graphene using the same

A method of pre-treating a substrate on which graphene is to be directly formed, the method comprising:

• pre-treating the substrate using a pre-treatment gas including at least a carbon source and hydrogen,
• wherein, in an initial period of the pre-treating the substrate, the carbon source and the hydrogen are simultaneously supplied to a chamber in which the substrate is disposed,
• wherein the pre-treating the substrate is performed in the chamber, and
• wherein a graphene seed is present on the substrate immediately after the pre-treating the substrate as a result of the pre-treating and a graphene layer is not present on the substrate immediately after the pre-treating the substrate.