▎ 摘　　要

NOVELTY - Controlling bandgap of diamond comprises preparing a diamond base material, converting the surface of the diamond base material into graphene by a predetermined thickness using high-density hydrogen plasma and adjusting the graphene length to control the band gap of diamond to less than 3 eV. USE - The method is useful for controlling bandgap of diamond. ADVANTAGE - The method can precisely control length of the graphene layer to a nano level. DESCRIPTION OF DRAWING(S) - The drawing shows a structure in which graphene is formed from a surface of a diamond base material and a density of state.