Abstract
Charge carrier scattering at grain boundaries (GBs) in a chemical vapor deposition (CVD) graphene reduces the carrier mobility and degrades the performance of the graphene device, which is expected to affect the quantum Hall effect (QHE). This study investigated the influence of individual GBs on the QH state at different stitching angles of the GB in a monolayer CVD graphene. The measured voltage probes of the equipotential line in the QH state showed that the longitudinal resistance (Rxx) was affected by the scattering of the GB only in the low carrier concentration region, and the standard QHE of a monolayer graphene was observed regardless of the stitching angle of the GB. In addition, a controlled device with an added metal bar placed in the middle of the Hall bar configuration was introduced. Despite the fact that the equipotential lines in the controlled device were broken by the additional metal bar, only the Rxx was affected by nonzero resistance, whereas the Hall resistance (Rxy) revealed the well-quantized plateaus in the QH state. Thus, our study clarifies the effect of individual GBs on the QH states of graphenes.
Highlights
Graphene is an atomically thin monolayer that has attracted considerable attention in many fields due to its excellent mechanical [1,2] and electronic properties [3,4] that make it a promising material for next-generation nanoelectronics [3,5,6,7]
A theoretical study of the quantum Hall effect (QHE) in polycrystalline graphene showed that the grain boundaries (GBs) destroy the QH state [28,29], and an experimental study of the QHE in polycrystalline chemical vapor deposition (CVD) graphene showed strong backscattering of charge carriers in the QH regime [30]
All graphene flakes presented in this study were synthesized on a copper (Cu) foil using chemical vapor deposition (CVD) at 1070 ◦ C with a mixture of hydrogen and methane gases
Summary
Graphene is an atomically thin monolayer that has attracted considerable attention in many fields due to its excellent mechanical [1,2] and electronic properties [3,4] that make it a promising material for next-generation nanoelectronics [3,5,6,7]. Hall effect (QHE) in graphene [8,9,10], defined by a vanishing of longitudinal resistance (Rxx ) accompanied by the quantized plateau of Hall resistance (Rxy ), can be observed at up to room temperature [11]. The novel quantum transport behavior can be studied efficiently without the sophisticated growth of high-quality, thin epitaxial films. The electrical transport between single-crystal domains can be affected by scattering at the GB [19,20,21,22,23,24]. The GB is a defect line consisting of a series of pentagonal, hexagonal, and heptagonal rings formed at the stitching region between two domains with different orientations [21,31,32].
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