Preparation method of graphene field effect transistor

The invention provides a preparation method a graphene field effect transistor. The method comprises the steps of: providing a semiconductor substrate, and forming aligning marks on the semiconductor substrate; forming a graphene film layer on the semiconductor substrate; imaging the graphene film layer by photo-etching and etching processes, and forming aligning marks of belt-shaped grapheme and the graphene film layer, wherein the belt-shaped graphene serving as a conductive channel; realizing the alignment of the belt-shaped graphene by utilizing the aligning marks formed on the substrate; forming a source electrode and a drain electrode on the belt-shaped graphene by photo-etching, metal deposition and peeling processes; and in the photo-etching process, aligning the source electrode and the drain electrode to the belt-shaped graphene by utilizing the aligning marks of the graphene film layer. According to the invention, the process of etching the alignment marks to the graphene by means of photo-etching and etching is omitted, so that the contact opportunity of graphene and photoresist is reduced, the residual of the photoresist on the graphene is further reduced, and the performance of the device is improved; in addition, the processing steps are reduced, so that the cost is lowered.