Elucidating Piezoelectricity and Strain in Monolayer MoS2 at the Nanoscale Using Kelvin Probe Force Microscopy

Strain engineering modifies the optical and
electronic properties of atomically thin transition metal dichalcogenides.
Highly inhomogeneous strain distributions in twodimensional
materials can be easily realized, enabling control of
properties on the nanoscale; however, methods for probing strain
on the nanoscale remain challenging. In this work, we characterize
inhomogeneously strained monolayer MoS2 via Kelvin probe force
microscopy and electrostatic gating, isolating the contributions of
strain from other electrostatic effects and enabling the measurement
of all components of the two-dimensional strain tensor on
length scales less than 100 nm. The combination of these methods
is used to calculate the spatial distribution of the electrostatic
potential resulting from piezoelectricity, presenting a powerful way
to characterize inhomogeneous strain and piezoelectricity that can be extended toward a variety of 2D materials.