Electrical resistivity of polycrystalline graphene: effect of grain-boundary-induced strain fields

Abstract

We have revealed the decisive role of grain-boundary-induced strain fields in electron scattering in polycrystalline graphene. To this end, we have formulated the model based on Boltzmann transport theory which properly takes into account the microscopic structure of grain boundaries (GB) as a repeated sequence of heptagon–pentagon pairs. We show that at naturally low GB charges the strain field scattering dominates and leads to physically reasonable and, what is important, experimentally observable values of the electrical resistivity. It ranges from 0.1 to 10 k$$\Omega$$ Ω $$\upmu m$$ μ m for different types of symmetric GBs with a size of 1 $$\upmu$$ μ m and has a strong dependence on misorientation angle. For low-angle highly charged GBs, two scattering mechanisms may compete. The resistivity increases markedly with decreasing GB size and reaches values of 60 k$$\Omega$$ Ω $$\upmu$$ μ m and more. It is also very sensitive to the presence of irregularities modeled by embedding of partial disclination dipoles. With significant distortion, we found an increase in resistance by more than an order of magnitude, which is directly related to the destruction of diffraction on the GB. Our findings may be of interest both in the interpretation of experimental data and in the design of electronic devices based on poly- and nanocrystalline graphene.

Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy

“…Ref. 85 calculated GB resistance as a function of angle, finding it to be significantly smaller for small-angle misalignment, while Ref. 86 suggested that non-straight GBs have substantially less misorientation angle dependence of the GB resistance at higher angles, while still decreasing rapidly ≤ 8°.…”

First principles study of electronic structure and transport in graphene grain boundaries

“…Using a Boltzmann transport equation (BTE) approach is also another approach that could be taken to model the impact of GBs [42], but it does so by considering a distribution of GBs, while in this work the atomic structure and the electronic and conductive properties which arise from this structure is considered using DFT-non-equilibrium Greens functions (NEGF). BTE is also usually assumes incoherent charge carriers scattering from a density of defects within linear response.…”

“…the long-ranged effects of variations in strain due to the presence of GBs [42] or substrate. On the scale of our computational cells we believe that the strain and substrate effects are secondary to the main scattering effects provided by the GB itself.…”