Single crystals of the layered dichalcogenides MoS2 and WS2 grown by liquid phase transport

TL;DR

This paper reports a method for growing high-quality single crystals of MoS2 and WS2 using a liquid salt flux, with detailed characterization showing high crystallinity and minimal intergrowths, and improved optical properties for MoS2.

Contribution

It introduces a liquid phase transport method for growing layered dichalcogenide crystals with enhanced crystallinity and minimal intergrowths.

Findings

Crystals are predominantly 2H-MoS2 with ~3% 3R intergrowths.

WS2 crystals show less than 1% 3R intergrowths.

MoS2 crystals exhibit superior photoluminescence compared to commercial samples.

Abstract

The growth of single crystals of MoS2 and WS2 by materials transport through a liquid salt flux made from a low melting mixture of NaCl and CsCl is described. The crystals are characterized by single crystal X-ray diffraction, which reveals that they are 2H-MoS2 with a small percentage (about 3%) of 3R intergrowths. The 2H-WS2 crystals display less than 1% of 3R intergrowths. Photoluminescence spectra of exfoliated monolayers suggest that MoS2 grown by this method has superior crystallinity in comparison to commercially-available MoS2 crystals.