Weak ferroelectric charge transfer in layer-asymmetric bilayers of 2D semiconductors

TL;DR

This paper investigates charge transfer phenomena in bilayer 2D semiconductors, revealing stacking-dependent effects in TMDs like WSe₂ and negligible transfer in InSe, with implications for moiré superlattice potentials.

Contribution

It provides a detailed analysis of layer-asymmetric charge transfer in bilayer 2D semiconductors, highlighting material-specific behaviors and their impact on moiré patterns.

Findings

WSe₂ bilayers exhibit significant stacking-dependent charge transfer.

InSe bilayers show negligible charge transfer.

Charge transfer influences the potential landscape in moiré superlattices.

Abstract

In bilayers of two-dimensional (2D) semiconductors with stacking arrangements which lack inversion symmetry charge transfer between the layers due to layer-asymmetric interband hybridisation can generate a potential difference between the layers. We analyse bilayers of transition metal dichalcogenides (TMDs) - in particular, WSe$_2$ - for which we find a substantial stacking-dependent charge transfer, and InSe, for which the charge transfer is found to be negligibly small. The information obtained about TMDs is then used to map potentials generated by the interlayer charge transfer across the moir\'e superlattice in twistronic bilayers.