▎ 摘　　要

NOVELTY - Preparing near free state single-layer graphene based on silicon carbide single crystal substrate comprises (i) grinding, polishing and cleaning the silicon surface of silicon carbide single crystal substrate wafer to obtain pre-processed substrate; (ii) placing the pre-processed substrate silicon surface upwards in the graphite crucible, using a crucible cover for sealing, heating the graphite crucible, introducing high purity hydrogen, and performing hydrogen etching on the surface of silicon carbide substrate to form a regular step morphology on the surface of silicon carbide substrate; (iii) obtaining substrate with non-uniform graphene completely covering the buffer layer; (iv) placing the substrate of non-uniform graphene completely covering the buffer layer in acetone, ultrasonically processing to expose the buffer layer, and obtaining the substrate only with uniform buffer layer; and (v) obtaining the near free state single-layer graphene USE - The method is useful for preparing near free state single-layer graphene based on silicon carbide single crystal substrate, which is used in the field of ultra-fast logic circuit, photoelectric detector, laser Q and high frequency radio frequency device. ADVANTAGE - The method greatly improves quality, surface morphology and electrical properties of the near-free state single-layer graphene. DETAILED DESCRIPTION - Preparing near free state single-layer graphene based on silicon carbide single crystal substrate comprises (i) grinding, polishing and cleaning the silicon surface of silicon carbide single crystal substrate wafer to obtain pre-processed substrate; (ii) placing the pre-processed substrate silicon surface upwards in the graphite crucible, using a crucible cover for sealing, placing the graphite crucible in a heating furnace chamber, vacuumizing the heating furnace chamber, heating to 1350-1750degreesC, introducing high purity hydrogen, and performing hydrogen etching on the surface of silicon carbide substrate to form a regular step morphology on the surface of silicon carbide substrate; (iii) turning off hydrogen gas, introducing argon gas, heating the heating furnace to 1600-1700degreesC, keeping the temperature for 30-90 minutes, completing the full coverage growth of graphene; after finishing growth, turning off heating power supply, continuously introducing argon gas, cooling temperature to less than or equal to 500degreesC, closing argon gas, naturally cooling to room temperature, and obtaining substrate with non-uniform graphene completely covering the buffer layer; (iv) placing the substrate of non-uniform graphene completely covering the buffer layer in acetone, ultrasonically processing for 10-120 minutes at 40-80 W ultrasonic power to dissociate remove non-uniform graphene to expose the buffer layer, and obtaining the substrate only with uniform buffer layer; and (v) placing the substrate with uniform buffer layer in a graphite crucible, sealing by a crucible cover, then placing in a heating furnace chamber, vacuumizing the heating furnace chamber, heating to 700-1100degreesC, introducing high pure hydrogen for hydrogen atom passivation, maintaining for 30-80 minutes, finishing the insertion of hydrogen atom, inserting foreign atoms between the buffer layer and the silicon carbide single crystal substrate to obtain single layer graphene in the near free state, cutting off the heating power supply, continuously introducing hydrogen, when the temperature is reduced to less than or equal to 500degreesC, closing hydrogen, introducing argon gas, naturally cooling to room temperature, and obtaining the near free state single-layer graphene.