NOVELTY - A graphoepitaxy channel comprising side walls and a floor is formed on a graphene substrate, a layer of surface-modifying copolymer is formed on the side walls and the floor of the channel. Then, a block copolymer is deposited in the channel and the block copolymer is subjected to predetermined conditions such that a striped pattern is formed on the graphene substrate. The striped pattern is transferred into the graphene substrate, to form graphene nanoribbon array.    USE - Fabrication of graphene nanoribbon array used for fabrication of field-effect transistor device. Uses include but are not limited to nanoelectronics, quantum computing, field-effect transistor, thin film flexible electronic, transparent electronic, high-electron mobility transistor, micro-electromechanical system, optoelectronic, photodetector, solar cell, and magnetic, mechanical and chemical sensor.    ADVANTAGE - The method efficiently and economically fabricates graphene nanoribbon array with excellent electronic properties.    DETAILED DESCRIPTION - A graphoepitaxy channel comprising side walls and a floor is formed on a graphene substrate, a layer of surface-modifying copolymer is formed on the side walls and the floor of the channel. Then, a block copolymer is deposited in the channel and the block copolymer is subjected to conditions under which spatial confinement of the block copolymer by the channel induces the block copolymer to self-assemble into lamellar domains in which lamellae are oriented perpendicular with respect to the graphene substrate surface and perpendicular with respect to the channel side walls or into a cylindrical domains in which the cylinders are oriented parallel with respect to the graphene substrate surface and perpendicular with respect to the channel side walls, such that a self-assembled block copolymer layer defines a striped pattern on the graphene substrate. The striped pattern is transferred into the graphene substrate, to form graphene nanoribbon array. An INDEPENDENT CLAIM is included for method of fabricating patterned graphene array, which involves forming a block copolymer on a graphene substrate and subjecting the block copolymer to conditions which induce to self-assemble into polymeric domains, such that the domains define a pattern on the graphene substrate, converting polymeric domains in the self-assembled block copolymer into inorganic domains comprising inorganic compounds, such that the inorganic domains define a pattern on the graphene substrate, and transferring the pattern of the inorganic domains into the graphene substrate to provide the patterned graphene array.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view explaining the fabrication of graphene nanoribbon array.    Bottom gate (102)    Dielectric gate (104)    Graphene sheets (106)    Source electrode (108)    Drain electrode (110)