Electronic Current Mapping of Transport through Defective Zigzag Graphene Nanoribbons

In this contribution, we aim at supporting theoretical transistor material design using a combination of electronic structure theory, transport simulations, and local current analysis. Our effort focuses on defective zigzag graphene nanoribbons (ZGNRs) to design molecular junctions with an atomically precisely controlled degree of defect dilution. Electronic structure calculations within a periodic density functional theory (DFT) framework yield information about the band structures. These serve as a guide for constructing a transport model of the nanojunctions composed of a defective ZGNR scattering region connected to pristine ZGNR leads. Performing nonequilibrium Green’s function simulations on selected systems of interest, their transport properties in the quasi-stationary limit are revealed. Following a recent procedure, associated current densities are mapped on a real-space representation. The presence of defects leads to concentrated current flow in the middle region, which is close to the defect edges. The degree of defect dilution as well as the width of the nanojunction have strong influences on the local current densities.