# Suppression of the Shear Raman Mode in Defective Bilayer MoS2

## TL;DR

This study examines how lattice defects from ion irradiation affect the low frequency Raman spectra of bilayer MoS2, revealing suppression of the shear mode linked to disorder.

## Contribution

It demonstrates the impact of defect engineering on Raman spectral features of bilayer MoS2 using ion irradiation and modeling.

## Key findings

- Shear mode redshifts with increased ion dose
- Shear mode is sharply suppressed compared to other peaks
- Crystallite size and orientation influence Raman changes

## Abstract

We investigate the effects of lattice disorders on the low frequency Raman spectra of bilayer MoS2. The bilayer MoS2 was subjected to defect engineering by irradiation with a 30 keV He+ ion beam and the induced morphology change was characterized by transmission electron microscopy. With increasing ion dose the shear mode is observed to redshift and it is also suppressed sharply compared to other Raman peaks. We use the linear chain model to describe the changes to the Raman spectra. Our observations suggest that crystallite size and orientation are the dominant factors behind the changes to the Raman spectra.