▎ 摘　　要

NOVELTY - A vessel having an opening is placed (220) into chemical vapor deposition chamber, and metal foil is positioned (210) in the vessel. The chemical vapor deposition chamber is evacuated (230), and hydrogen gas is introduced (240) into the chamber to achieve a pressure (p1) of less than atmospheric pressure. The atmosphere in the chamber is heated (250) to anneal the metal foil, and methane and hydrogen are introduced (260) into the chamber to achieve pressure (p2) of less than atmospheric pressure. Then, carbon is deposited (270) on metal foil to grow graphene layer on the metal foil. USE - Method for growing graphene layer on metal foil used for forming field-effect transistor e.g. back-gated field-effect transistor, and device e.g. hall-bar device (all claimed). ADVANTAGE - The method enables controlled growth of graphene layer with four lobes and six lobes by varying growth pressure and methane to hydrogen ratio. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) single-crystalline graphene layer; (2) field-effect transistor, which has graphene layer; (3) formation of field-effect transistor, which involves providing silicon substrate, providing thermal oxide on the silicon substrate, forming a graphene channel by transferring the graphene layer from the metal foil onto the thermal oxide layer, depositing source electrode at one end of the graphene channel, and depositing a drain electrode at another end of the graphene channel; and (4) device, which is obtained by transferring graphene layer onto hexagonal boron nitride, and has electron mobility of 20000 cm2V-1second-1. DESCRIPTION OF DRAWING(S) - The drawing shows a flow chart explaining vapor-trapping method for graphene growth. Positioning metal foil in vessel (210) Placing vessel into chemical vapor deposition chamber (220) Evacuating chemical vapor deposition chamber (230) Introducing hydrogen gas into the chamber (240) Heating the atmosphere in the chamber (250) Introducing methane and hydrogen into the chamber (260) Depositing carbon on metal foil (270)