  In situ electron microscopy is a key tool for understanding the mechanisms
driving novel phenomena in 2D structures. Unfortunately, due to various
practical challenges, technologically relevant 2D heterostructures prove
challenging to address with electron microscopy. Here, we use the differential
phase contrast imaging technique to build a methodology for probing local
electrostatic fields during electrical operation with nanoscale precision in
such materials. We find that by combining a traditional DPC setup with a high
pass filter, we can largely eliminate electric fluctuations emanating from
short-range atomic potentials. With this method, a priori electric field
expectations can be directly compared with experimentally derived values to
readily identify inhomogeneities and potentially problematic regions. We use
this platform to analyze the electric field and charge density distribution
across layers of hBN and MoS2.
