Piezoelectric conversion in TMDCs Heterostructure Atomic Layers

TL;DR

This paper investigates the piezoelectric properties of WSe2/MoS2 heterostructures, demonstrating significant voltage outputs influenced by stacking type, layer number, and strain, with implications for nanoscale electromechanical systems.

Contribution

It provides new insights into how stacking configurations and layer interactions affect piezoelectricity in TMDC heterostructures, enabling improved NEMS device design.

Findings

AB-stacking yields higher output voltage than AA-stacking.

Output voltages of 0.137 V and 0.183 V at 4% and 8% strain.

AB-stacking has lower formation energy and better stability.

Abstract

Two-dimensional heterostructure of WSe2/MoS2 atomic layers has unique piezoelectric characteristics which depends on the number of atomic layer, stacking type, and interlayer interaction size. The van der Waals heterostructure of p- and n-type TMDC atomic layers with different work functions forms a staggered gap alignment. The large band offset of conduction band minimum and valence band maximum between p-type WSe2 and n-type MoS2 atomic layers leads to the large electric polarization and piezoelectricity. The output voltages for a MoS2/WSe2 partial vertical heterostructure with a size of 3.0 nm and 1.5 nm were 0.137 V and 0.183 V for 4% and 8% tensile strains, respectively. The output voltage of AB-stacking MoS2/WSe2 heterostructure was larger than that of AA-stacking heterostructure for 4% tensile strain due to the contribution of intrinsic piezoelectricity and the symmetric condition in out-of-plane. The AB-stacking has a lower formation energy and better structural stability compared to AA-stacking. The large output voltage of nanoscale partial or full vertical heterostructure of 2D WSe2/MoS2 atomic layers in addition to the increased output voltage through series connection of multiple nanoscale piezoelectric devices will enable the realization of nano electromechanical systems (NEMS) with TMDC heterostructure atomic layers.