Low wavenumber Raman spectroscopy of highly crystalline MoSe2 grown by chemical vapor deposition

TL;DR

This paper demonstrates the use of low wavenumber Raman spectroscopy to characterize the layer number and quality of MoSe2 monolayers and few-layer crystals grown by chemical vapor deposition, highlighting its potential for material assessment.

Contribution

It introduces low frequency Raman mapping as a novel method to evaluate the symmetry, quality, and layer number of CVD-grown MoSe2, correlating vibrational modes with layer thickness.

Findings

First-time presentation of low frequency Raman spectra for MoSe2

Correlation between Raman modes and layer number

Validation of Raman mapping for quality assessment

Abstract

Transition metal dichalcogenides (TMDs) have recently attracted attention due to their interesting electronic and optical properties. Fabrication of these materials in a reliable and facile method is important for future applications, as are methods to characterize material quality. Here we present the chemical vapor deposition of MoSe2 monolayer and few layer crystals. These results show the practicality of using chemical vapor deposition to reliably fabricate these materials. Low frequency Raman spectra and mapping of shear and layer breathing modes of MoSe2 are presented for the first time. We correlate the behavior of these modes with layer number in the materials. The usefulness of low frequency Raman mapping to probe the symmetry, quality, and monolayer presence in CVD grown 2D materials is emphasized.