Continuously tunable electronic structure of transition metal dichalcogenides superlattices

TL;DR

This study theoretically demonstrates that superlattices of MoS₂ and WSe₂ can have their electronic band gaps continuously tuned by adjusting layer ratios, promising for infrared optoelectronic applications.

Contribution

It introduces a method to control the electronic structure of TMDC superlattices via layer ratio, maintaining direct band gaps under strain.

Findings

K-K band gap tunable from 0.14 eV to 0.5 eV

Band gap remains direct under certain strains

Valence and conduction bands are spatially separated

Abstract

Two dimensional transition metal dichalcogenides (TMDC) have very interesting properties for optoelectronic devices. In this work we theoretically investigate and predict that superlattices comprised of MoS$_{2}$ and WSe$_{2}$ multilayers possess continuously tunable electronic structure having direct band gap. The tunability is controlled by the thickness ratio of MoS$_{2}$ versus WSe$_{2}$ of the superlattice. When this ratio goes from 1:2 to 5:1, the dominant K-K direct band gap is continuously tuned from 0.14 eV to 0.5 eV. The gap stays direct against -0.6% to 2% in-layer strain and up to -4.3% normal-layer compressive strain. The valance and conduction bands are spatially separated. These robust properties suggest that MoS$_{2}$ and WSe$_{2}$ multilayer superlattice should be an exciting emerging material for infrared optoelectronics.