Effectively Modulating Vertical Tunneling Transport by Mechanically Twisting Bilayer Graphene within All-metallic Architecture
Bilayer graphene possesses new degrees of freedom for modulating the electronic band structure, which makes it an attempting solution for overcoming the intrinsic absence of sizeable bandgap in graphene and designing the next-generation devices for the post-silicon electronics. By twisting bilayer graphene, the interlayer hybridized and twist angle-dependent van Hove singularities in the electronic band structure are generated and expected to facilitate the vertical tunneling transport between bilayer graphene. We herein, based on the ab initio quantum transport simulations, designed a novel all-metallic vertical quantum transport architecture, in which the twisted bilayer graphene as the transport channel region and the Au electrodes as the source/drain-contacts, to investigate the twist angle-dependent vertical transport properties. A 2 orders of magnitude current ION/IOFF ratio can be achieved by simply twisting the bilayer graphene. Comparing to the traditional gate voltage modulation which tunes the Fermi energy level alone, current strategy shifts the Fermi energy level of channel region away from the Dirac cone, moves the Fermi level and the van Hove singularities towards each other and promotes the vertical quantum transport due to the interlayer electronic hybridization. This dual modulation strategy of this novel mechanical gating device thus provides a potentially new solution for designing novel vertical transistors.