▎ 摘　　要

NOVELTY - A graphene multiple-valued logic device comprises: a substrate (10); a graphene channel layer (20) disposed on the substrate; source and drain electrodes (30a, 30b) disposed at both ends of the graphene channel layer, respectively; an insulator film (40) formed on the graphene channel layer; and at least two gate electrodes (50a, 50b) disposed on the insulator film with a predetermined gap defined between them. USE - As graphene multiple-valued logic device (claimed) used in ultra large scale integration (ULSI) or very large scale integration (VLSI). ADVANTAGE - The device allows adjustment of conductivity and resistance of the graphene channel layer depending on a gate voltage, where electric current flowing in the device can be variously changed when applied to a multiple-valued logic system. Also, based on a state of the graphene channel layer at a back gate reference voltage, since channels having different conduction types can be formed in the graphene channel layer upon application of gate voltage, a device optimized to realize the multiple-valued logic system can be provided. Since a circuit of the multiple-valued logic system can be simplified, the graphene multiple-valued logic device has an advantage of high integration. DETAILED DESCRIPTION - A graphene multiple-valued logic device comprises: a substrate (10); a graphene channel layer (20) disposed on the substrate; source and drain electrodes (30a, 30b) disposed at both ends of the graphene channel layer, respectively; an insulator film (40) formed on the graphene channel layer; and at least two gate electrodes (50a, 50b) disposed on the insulator film with a predetermined gap defined between them. A ground voltage is applied to a region in the graphene channel layer facing the predetermined gap between the gate electrodes through the substrate. The graphene channel layer has one selected from among p-type, n-type and i-type conductivities in a region facing the gate electrodes depending on voltage applied to the gate electrodes. The source and drain electrodes overlap at least one of the gate electrodes. INDEPENDENT CLAIMS are included for the following: (1) operating a graphene multiple-valued logic device involving: providing a graphene multiple-valued logic device; determining a conduction type of the graphene channel layer by applying a ground voltage to the graphene channel layer disposed between the first and second gate electrodes; forming a conduction type of the graphene channel layer facing the first gate electrode by applying a positive or negative gate voltage to the first gate electrode with reference to the ground voltage; forming a conduction type of the graphene channel layer facing the second gate electrode by applying a positive or negative gate voltage to the second gate electrode with reference to the ground voltage; and calculating total resistance of the graphene channel layer varying with voltage applied to the first and second gate electrodes; and (2) fabricating a graphene multiple-valued logic device involving: forming a graphene channel layer on a substrate; forming source and drain electrodes at both ends of the graphene channel, respectively; forming an insulator film on the graphene channel layer on which the source and drain electrodes are formed; and forming at least two gate electrodes on the insulator film. DESCRIPTION OF DRAWING(S) - The figure shows resistance change of a graphene multiple-valued logic device. Substrate (10) Graphene channel layer (20) Third channel region (20c) Source electrodes (30a) Drain electrodes (30b) Insulator film (40) First and second gate electrodes (50a, 50b)