Direct Transformation of Crystalline MoO into Few-Layers MoS.

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