Charge Transport in Polycrystalline Graphene: Challenges and Opportunities

Abstract

Graphene has attracted significant interest both for exploring fundamental science and for a wide range of technological applications. Chemical vapor deposition (CVD) is currently the only working approach to grow graphene at wafer scale, which is required for industrial applications. Unfortunately, CVD graphene is intrinsically polycrystalline, with pristine graphene grains stitched together by disordered grain boundaries, which can be either a blessing or a curse. On the one hand, grain boundaries are expected to degrade the electrical and mechanical properties of polycrystalline graphene, rendering the material undesirable for many applications. On the other hand, they exhibit an increased chemical reactivity, suggesting their potential application to sensing or as templates for synthesis of one-dimensional materials. Therefore, it is important to gain a deeper understanding of the structure and properties of graphene grain boundaries. Here, we review experimental progress on identification and electrical and chemical characterization of graphene grain boundaries. We use numerical simulations and transport measurements to demonstrate that electrical properties and chemical modification of graphene grain boundaries are strongly correlated. This not only provides guidelines for the improvement of graphene devices, but also opens a new research area of engineering graphene grain boundaries for highly sensitive electro-biochemical devices.

Scaling properties of polycrystalline graphene: a review

“…GB G , where R S is the sheet resistance of the polycrystalline sample, R S 0 is the sheet resistance within the grains, and l G is the average grain size [26].…”

All‐Carbon Thin‐Film Transistors as a Step Towards Flexible and Transparent Electronics

“…Note that CVD-grown graphene is intrinsically polycrystalline, with graphene grains stitched together by grain boundaries that act as a source of intrinsic carrier scattering and degrade the electrical properties. [106] Thus, one promising approach is to reduce the number of grain boundaries by growing large-size grains or even a single crystal film to improve the optoelectrical performance of graphene TCFs, but this remains a great challenge. [103,107] The transfer process of etching away the copper not only leads to inevitable damage to the graphene, the production of metal residues and serious environmental pollution, it also increases production cost.…”

Mesoscopic current transport in two-dimensional materials with grain boundaries: Four-point probe resistance and Hall effect

“…9. It follows that the expected effective sheet conductance normalized to the intra grain sheet conductance becomes…”

“…GBs are presently ubiquitous in CVD processed material since the technique relies on stitching together-initially separate-grains in order to achieve larger coherent sheets. 5 Both theoretical 6,7 and experimental studies 8,9 on transport through graphene GBs found that GBs cause potential barriers for the carrier transport and result in an increase in resistance, which sometimes is 30 times larger than the bulk graphene resistance at the center of the grain. [10][11][12] Thus, the GBs are significantly deteriorating the electrical properties of the films, which in turn affect the performance of graphene based devices, e.g., field-effect transistors.…”