Liquid Salt Transport Growth of Single Crystals of the Layered Dichalcogenides MoS2 and WS2

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 presented. The crystals are structurally characterized by single-crystal X-ray diffraction, which reveals that the 2H-MoS2 crystals contain a very small percentage (about 3%) of 3R intergrowths and that the 2H-WS2 crystals display less than 1% of 3R intergrowths. Characterization of the crystals by scanning electron microscopy is presented as are photoluminescence spectra of exfoliated monolayers that show that MoS2 crystals grown by this method are superior in quality to commercially available MoS2 crystals and equivalent to the current state of the art.