Van der Waals structures formed by aligning monolayer graphene withinsulating layers of hexagonal boron nitride exhibit a moir\'e superlatticethat is expected to break sublattice symmetry. Despite an energy gap of severaltens of millielectron volts opening in the Dirac spectrum, electricalresistivity remains lower than expected at low temperature and varies betweendevices. While subgap states are likely to play a role in this behavior, theirprecise nature is unclear. We present a scanning gate microscopy study ofmoir\'e superlattice devices with comparable activation energy but withdifferent charge disorder levels. In the device with higher charge impurity(~${10}^{10}$ $cm^{-2}$) and lower resistivity (~$10$ $k{\Omega}$) at the Diracpoint we observe current flow along the graphene edges. Combined withsimulations, our measurements suggest that enhanced edge doping is responsiblefor this effect. In addition, a device with low charge impurity (~$10^9$$cm^{-2}$) and higher resistivity (~$100$ $k{\Omega}$) shows subgap states inthe bulk, consistent with the absence of shunting by edge currents.
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机译：通过在六角形氮化硼的绝缘层内排列单层石墨烯而形成的范德华结构显示出有望破坏亚晶格对称性的莫尔超晶格。尽管在狄拉克谱中打开了数十毫伏的能隙，但电阻率仍低于低温下的预期值，并且在器件之间会发生变化。虽然子间隙状态可能在这种行为中起作用，但其精确性尚不清楚。我们提出了具有可比的活化能但具有不同电荷无序水平的莫尔超晶格器件的扫描门显微镜研究。在Diracpoint上具有较高电荷杂质（〜$ {10} ^ {10} $ $ cm ^ {-2} $）和较低电阻率（〜$ 10 $ $ k {\ Omega} $）的器件中，我们观察到电流沿石墨烯边缘。结合仿真，我们的测量表明增强的边缘掺杂是造成这种效应的原因。此外，具有低电荷杂质（〜$ 10 ^ 9 $$ cm ^ {-2} $）和较高电阻率（〜$ 100 $ $ k {\ Omega} $）的器件在整体上显示出亚带隙状态，这与不存在边沿电流分流。
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