title: Enhanced current-rectification in bilayer graphene with an electrically tuned sloped bandgap.
abstract: We propose a novel sloped dielectric geometry in graphene as a band engineering method for widening the depletion region and increasing the electrical rectification effect in graphene pn junctions. Enhanced current-rectification was achieved in a bilayer graphene with a sloped dielectric top gate and a normal back gate. A bias was applied to the top gate to induce a spatially modulated and sloped band configuration, while a back-gate bias was applied to open a bandgap. The sloped band can be tuned to separate n- and p-type regions in the bilayer graphene, depending on a suitable choice of gate voltage. The effective depletion region between the n- and p-type regions can be spatially enlarged due to the proposed top-gate structure. As a result, a strong non-linear electric current was observed during drain bias sweeping, demonstrating the expected rectification behavior with an on/off ratio higher than all previously reported values for graphene pn junctions. The observed rectification was modified to a linear current-voltage relationship by adjusting the biases of both gates to form an nn- or pp-type junction configuration. These results demonstrate that an external voltage can control the current flow in atomic film diodes.
authors.affiliation: WPI-MANA, NIMS, Tsukuba 305-0047, Japan.
authors.forename: Alex
authors.initials: A
authors.lastname: Aparecido-Ferreira
authors.forename: Hisao
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Song-Lin
authors.initials: SL
authors.lastname: Li
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Komatsu
authors.forename: Shu
authors.initials: S
authors.lastname: Nakaharai
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Tsukagoshi