▎ 摘　　要

NOVELTY - The method involves preparing a graphene film on a metal substrate. The graphene is transferred to a silicon substrate. The PMMA layer on the surface of the graphene is removed to obtain first sample. The photolithography is performed on the graphene first sample to construct a source-drain electrode shape to obtain second sample. The surface of the graphene obtained is vapor-deposited on the surface of the graphene, and after peeling, the source electrode and the drain electrode are respectively formed to obtain third sample. The third sample obtained is patterned by oxygen plasma etching to obtain a graphene sample. The surface of the base layer of the graphene sample is wiped with hydrofluoric acid. The silicon substrate of the base layer is exposed, thus served as a back gate of the field effect transistor. A primary field effect transistor is obtained. USE - Method of preparing field effect transistor. ADVANTAGE - The method effectively opens the band gap of graphene, and no chemical agent is doped to graphene. The strict requirements on the size of graphite are not needed.