  Tunability of polar and semiconducting properties of low-dimensional
transition metal dichalcogenides (TMDs) have propelled them to the forefront of
fundamental and applied physical research. These materials can vary from
non-polar to ferroelectric, and from direct-band semiconductor to metallic.
However, in addition to classical controls such as composition, doping, and
field effect in TMDs the additional degrees of freedom emerge due to the
curvature-induced electron redistribution and associated changes in electronic
properties. Here we numerically explore the elastic and electric fields,
flexoelectric polarization and free charge density for a TMD nanoflake placed
on a rough substrate with a sinusoidal profile of the corrugation using finite
element modelling. Numerical results for different flake thickness and
corrugation depth yield insight into the flexoelectric nature of the
out-of-plane electric polarization and establish the unambiguous correlation
between the polarization and static conductivity modulation caused by
inhomogeneous elastic strains coupled with deformation potential and strain
gradients, which evolve in TMD nanoflake due to the adhesion between the flake
surface and corrugated substrate. We revealed a pronounced maximum at the
thickness dependences of the electron and hole conductivity of MoS2 and MoTe2
nanoflakes placed on a metallic substrate, which opens the way for their
geometry optimization towards significant improvement their polar and
electronic properties, necessary for their advanced applications in
nanoelectronics and memory devices.Specifically, obtained results can be useful
for elaboration of nanoscale straintronic devices based on the bended MoS2,
MoTe2 and MoSTe nanoflakes, such as diodes and bipolar transistors with a
bending-controllable sharpness of p-n junctions.
