Growth of Monolayer MoS Flakes via Close Proximity Re-Evaporation.

We report a two-step growth process of MoS nanoflakes using a low-pressure chemical vapor deposition technique. In the first step, a MoS layer was synthesized on a c-plane sapphire substrate. This layer was subsequently re-evaporated at a higher temperature to form mono- or few-layer MoS flakes. As a result, the close proximity re-evaporation enabled the growth of pristine MoS nanoflakes. Atomic force microscopy analysis confirmed the synthesis of nanoclusters/nanoflakes with lateral dimensions of over 10 μm and a flake height of approximately 1.3 nm, demonstrating bi-layer MoS, whereas transmission electron microscopy analysis revealed triangular MoS nanoflakes, with a diffraction pattern proving the presence of single crystalline hexagonal MoS. Raman data revealed the typical modes of high-quality MoS nanoflakes. Finally, we presented the photocurrent dependence of a MoS-based photoresist under illumination with light-emitting diode of 405 nm wavelength. The measured current-voltage dependence across various luminous flux outlined the sensitivity of MoS to polarized light and thus opens further opportunities for applications in high-performance photodetectors with polarization sensitivity.