Quantum Transport in Graphene-Based Heterojunctions

Graphene nanoribbons (GNRs) with unique and tunable electronic properties are promising candidates for a variety of nanotechnology applications. Recent advances in bottom-up synthesis have enabled design of tailored 2D semiconducting graphene-based nanocircuits using 1D GNRs. In this work, we investigate the electronic structure and conductance of semiconducting strained 1D and 2D GNR heterojunctions with emergent topological states. We use first-principles density functional theory and non-equilibrium Green’s function calculations to compute the electronic band structure and conductance of the various heterojunctions. First, we show that the strength of the topological states in heterojunctions can be controlled by manipulating the band alignment of the connected GNRs through optimizing the lateral length and doping in the GNRs. Then, we investigate the current-voltage characteristics and the electronic conductance of the 1D and 2D structures under uniaxial mechanical strain. Our results show that higher current and conductance are obtained as an increasing compressive strain is applied at a given bias. The reported electronic characteristics of the strained GNR heterojunctions aim to facilitate development of efficient flexible nanoelectronics.