Laser-Assisted Chemical Modification of Monolayer Transition Metal Dichalcogenides

TL;DR

This paper demonstrates a laser-assisted method for locally converting monolayer transition metal dichalcogenides from selenium to sulfur, enabling precise patterning of chemically distinct 2D material domains for nanodevice applications.

Contribution

It introduces a controlled laser-assisted chemical process for spatially selective modification of TMDs, preserving crystalline quality and enabling on-demand heterostructure synthesis.

Findings

Successful local selenium-to-sulfur conversion in TMDs.

Real-time Raman and photoluminescence monitoring of the process.

Heterogeneous structures retain high crystalline quality.

Abstract

Laser-assisted chemical modification is demonstrated on ultra-thin transition-metal dichalcogenides (TMDs), locally replacing selenium by sulfur atoms. The photo-conversion process takes place in a controlled reactive gas environment and the heterogeneous reaction rates are monitored via in situ real-time Raman and photoluminescence spectroscopies. The spatially localized photo-conversion resulted in a heterogeneous TMD structure, with chemically distinct domains, where the initial high crystalline quality of the film is not affected during the process. This has been further confirmed via transmission electron microscopy as well as Raman and Photoluminescence spatial maps. Our study demonstrates the potential of laser-assisted chemical conversion for on-demand synthesis of heterogeneous two-dimensional materials with applications in nanodevices.