▎ 摘　　要

NOVELTY - The method involves applying a voltage across a region of single layer graphene (SLG) such that nano-gap extending across the entire width of the SLG is formed. The region across which the voltage is applied is set with a point which is the narrowest in the region. The voltage is increased while recording the current and decreased when the current drops, while forming the nano-gap such that the current is increased while recording the voltage, and decreased when the voltage rises. The width of the nano-gap is determined by analyzing the current-voltage measurement. USE - Method for forming nano-gaps in graphene used in electronic device, molecular device or electronic circuit (all claimed). ADVANTAGE - The nano-gaps in graphene is formed efficiently with required size. DETAILED DESCRIPTION - The width of the nano-gap is set in the range of 0.1-5 nm. The graphene is formed of chemical vapor deposition (CVD)-grown graphene, which is provided in the form of ribbon comprising notch prior to application of the voltage. INDEPENDENT CLAIMS are included for the following: (1) graphene structure which has graphene sheets separated by nano-gap, graphene electrodes and graphene nano-gap array; and (2) method for detecting or characterizing molecule in sample, which involves contacting the sample with graphene structure for detecting the change in voltage or tunneling current across the gap. The presence of molecule in the sample is indicated for obtaining the characteristics of the molecule. The molecule is formed of macromolecule, DNA or RNA. DESCRIPTION OF DRAWING(S) - The drawing shows a graph illustrating the SLG nano-gap, barrier width and barrier asymmetry.