# Resolving the On–Off Ratio Discrepancy in Bilayer 3R-MoS2 FeSFETs: Dual Mechanisms of Domain Wall Engineering

## TL;DR

This paper explains how domain walls in MoS2 transistors can improve their switching performance by altering electronic properties.

## Contribution

The study reveals dual mechanisms of domain wall engineering in enhancing polarization and suppressing OFF-state current in FeSFETs.

## Key findings

- Domain walls induce electronic reconstruction, enhancing polarization in neighboring ferroelectric domains.
- Local compressive strain in domain walls increases conduction band minimum, suppressing OFF-state current.
- Devices with domain walls show significantly higher ON-OFF ratios compared to single-domain devices.

## Abstract

Bilayer 3R-MoS2 ferroelectric semiconductor
field-effect
transistors (FeSFETs) commonly attributed the device’s ON-OFF
switching to reversible transformation between up and down polarization,
without considering the electronic properties of the domain walls
(DWs) in MoS2. In this work, we use density functional
theory combined with nonequilibrium Green’s function methods
to show that DWs formation would induce electronic reconstruction
at neighboring ferroelectric domains, thereby enhancing their polarization.
We also found that local compressive strain in the DW can effectively
increase the local conduction band minimum, drastically suppress the
OFF-state current in FeSFETs. While pristine single-domain devices
exhibit ON-OFF ratios of only 6.5 (armchair) and 3.8 (zigzag) at V

G
= 0 V, junctions
incorporating DWs can yield remarkably higher ratios of 99.1 and 33.5,
respectively. This work establishes that enhanced polarization and
suppressed conductance due to DWs present new avenues for improving
the performance of MoS2-based FeSFETs.