Mask-free patterning and selective CVD-growth of 2D-TMDCs semiconductors

This work reports on a novel mask-free approach that enables controlled selective growth of molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) crystalline islands on Si/SiO₂ substrates. In particular, the direct-write patterning technique and chemical vapor deposition method are employed to produce arrays of 2D-TMDCs nanostructures at pre-defined locations on the substrates. It is shown that by adjusting the patterning parameters, composition and concentrations of ink-precursors, and the growth conditions, patterns of MoS₂ and WS₂ nanostructures with controlled geometry can be produced. The prepared 2D-TMDCs materials were analyzed by atomic force microscopy, Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, all of which indicated to high-quality double-layer MoS₂ and WS₂ nanostructures. The back-gated field effect transistors were fabricated, and their charge carrier mobility values of 11 cm² V^-1 s^-1 for MoS₂ and 4 cm² V^-1 s^-1 for WS₂ were extracted from the device measurements.