▎ 摘　　要

NOVELTY - A liquid copper substrate preparing method involves placing a solid copper on a copper-tungsten alloy substrate, and heating in a hydrogen atmosphere until the reactor temperature reaches above the melting point of copper. USE - Method for preparing a liquid copper substrate that is utilized for preparing a large single crystal graphene in a field effect transistor device (claimed). ADVANTAGE - The method enables providing uniform nucleation rate and rapid growth rate of graphene using the liquid copper substrate, and achieving controllable size of grapheme. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for preparing a large single crystal graphene, which involves using chemical vapor deposition in an inert gas atmosphere and under hydrogen, catalytic cracking of the copper substrate surface, forming a large single crystal grown graphene, and cooling under an inert gas atmosphere to room temperature to obtain the large single crystal graphene.