Speaker
Description
The recent bottom-up synthesis of a crystal lattice of nanoporous graphene (NPG) gives a way of making new multifunctional carbon material [1]. In addition, by forming NPG/graphene (Grp) bilayers, graphene can exhibit various functionalities depending on the sizes, shapes, and periodicity of nanopores in NPG. Here, we present two mechanisms for the electric-field-tunable bandgap in NPG/Grp bilayers: (i) type-I bandgap opening in graphene through 2D inversion symmetry breaking and (ii) type-II bandgap opening through the merging of Dirac cones of graphene [2]. To translate the underlying physics of the bandgap opening in graphene into real atomic structures, we develop an inverse design method and find NPG/Grp bilayers with the target functionality. First-principles calculations show that the inverse-designed NPG/Grp bilayers indeed exhibit the field-tunable bandgaps in graphene as predicted; the type-I bandgap opening is characterized by a linear field dependence of the bandgap, while the type-II bandgap opening exhibits a highly nonlinear field dependence of the bandgap. The field-tunable bandgap in graphene, supported by first-principles calculations for the inverse-designed systems, holds promise for new types of graphene transistors.
[1] C. Moreno et al., Science 2018, 360, 199-203.
[2] B. Lee and J. Kang, Adv. Electron. Mater. 2022, 2200252.
