Observation of Piezoelectricity in Monolayer Molybdenum Disulfide

TL;DR

This paper provides the first experimental evidence of piezoelectricity in monolayer MoS2, revealing its potential for nanoscale electromechanical applications due to atomic-level symmetry breaking.

Contribution

It reports the first experimental demonstration of piezoelectricity in monolayer MoS2 and introduces a method to determine 2D crystal orientation via electro-mechanical coupling.

Findings

Piezoelectric coefficient e11 measured as 2.9e-10 C/m.

Only odd-layer MoS2 exhibits piezoelectricity.

Piezoelectricity enables scaling NEMS to atomic dimensions.

Abstract

Piezoelectricity offers precise and robust conversion between electricity and mechanical force. Here we report the first experimental evidence of piezoelectricity in a single layer of molybdenum disulfide (MoS2) crystal as a result of inversion symmetry breaking of the atomic structure, with measured piezoelectric coefficient e11 = 2.9e-10 C/m. Through the angular dependence of electro-mechanical coupling, we uniquely determined the two-dimensional (2D) crystal orientation. We observed that only MoS2 membranes with odd number of layers exhibited piezoelectricity, in sharp contrast to the conventional materials. The piezoelectricity discovered in single molecular membrane promises scaling down of nano-electro-mechanical systems (NEMS) to single atomic unit cell - the ultimate material limit.