▎ 摘　　要

NOVELTY - Band gap-retained graphene comprises graphene (10), and an ion having energy of less than 50 eV provided on the graphene. The graphene has band gap of 0.1-0.65 eV. USE - The band gap retained graphene is useful for graphene-based semiconductor and electronic devices. ADVANTAGE - The band gap retained graphene has low-energy ion adsorption with little loss in graphene, and intrinsic properties. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) producing band gap retained graphene by adsorbing ions having energy of less than 50 eV on the graphene; and (2) measuring adsorption amount ions, comprising (i) measuring work function change with respect to adsorption amount of unit layer (1 ml:1 monolayer) unit, and (ii) converting the work variation into an adsorbed ion content. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of formation of the band gap in graphene (Drawing includes non-English language text). Graphene (10) Silicon carbide substrate (20) Alkali metal ion (30)