Direct transformation of crystalline MoO${}_3$ into few-layers MoS${}_2$

We fabricate large-area atomically thin MoS${}_2$ layers through the direct transformation of crystalline molybdenum MoS${}_2$ (MoO${}_3$) by sulfurization at relatively low temperatures. The obtained MoS2 sheets are polycrystalline (~10-20 nm single-crystal domain size) with areas of up to 300x300 um${}^2$ with 2-4 layers in thickness and show a marked p-type behaviour. The synthesized films are characterized by a combination of complementary techniques: Raman spectroscopy, X-ray diffraction, transmission electron microscopy and electronic transport measurements.