▎ 摘　　要

Van der Waals structures formed by aligning monolayer graphene with insulating layers of hexagonal boron nitride exhibit a moire superlattice that is expected to break sublattice symmetry. Despite an energy gap of several tens of millielectronvolts opening in the Dirac spectrum, electrical resistivity remains lower than expected at low temperature and varies between devices. While subgap states are likely to play a role in this behavior, their precise nature is unclear. We present a scanning gate microscopy study of moire superlattice devices with comparable activation energy but with different charge disorder levels. In the device with higher charge impurity (similar to 10(10) cm(-2)) and lower resistivity (similar to 10 K Omega) at the Dirac point we observe current flow along the graphene edges. Combined with simulations, our measurements suggest that enhanced edge doping is responsible for this effect. In addition, a device with low charge impurity (similar to 10(9) cm(-2)) and higher resistivity (similar to 100 K Omega) shows subgap states in the bulk, consistent with the absence of shunting by edge currents.