Spatial Mapping of Electrostatics and Dynamics across 2D Heterostructures

TL;DR

This paper introduces a novel electron microscopy technique combining differential phase contrast with high pass filtering to accurately map local electrostatic fields in 2D heterostructures during operation, overcoming previous practical challenges.

Contribution

The authors develop a new methodology for nanoscale electrostatic mapping in 2D heterostructures using in situ electron microscopy with enhanced filtering techniques.

Findings

Effective elimination of atomic potential fluctuations in electric field measurements.

Ability to compare expected and measured electric fields to identify inhomogeneities.

Application to analyze charge distribution in hBN and MoS2 layers.

Abstract

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.