▎ 摘　　要

A relative rotation of 90 degrees between two graphene nanoribbons (GNRs) creates a crossbar with a nanoscale overlap region. Calculations, based on the first principles density functional theory (DFT) and the nonequilibrium Green's function (NEGF) formalism, show that the electronic states of the individual GNRs of an unbiased crossbar are decoupled from each other similar to the decoupling that occurs in twisted bilayer graphene. Analytical calculations, based on Fermi's golden rule, reveal that the decoupling is a consequence of the cancellation of quantum phases of the electronic wave functions of the individual GNRs. As a result, the inter-GNR transmission is strongly suppressed over a large energy window. An external bias applied between the GNRs changes the relative phases of the wave functions resulting in modulation of the transmission and current by several orders of magnitude. A built-in potential between the two GNRs can lead to a large peak-to-valley current ratio (> 1000) resulting from the strong electronic decoupling of the two GNRs that occurs when they are driven to the same potential. Current switching by voltage control of the quantum phase in a graphene crossbar structure is a novel switching mechanism. It is robust even with an overlap of similar to 1.8 nmx 1.8 nm that is well below the smallest horizontal length scale envisioned in the international technology roadmap for semiconductors (ITRS).