Structural and optical characterization of MoS2 quantum dots defined by thermal annealing

We report a new approach to the synthesis of molybdenum disulfide (MoS2) quantum dots (QDs) that uses a single layer MoS2 grown by chemical vapor deposition (CVD) method as a precursor. The MoS2 QDs were formed by a thermal annealing process at 500 °C for 70 h to reduce the particle size. The results indicated that CVD-MoS2 covered almost area of the substrate, which showed a typical single layer thickness and 2H-MoS2 structure. A blue shift from 682 nm to 548 nm wavelength was observed in the photoluminescence (PL) spectra. It shows a successful formation of QDs with 4-7 nm small size from the large sized layers. This process is relatively easy for defining MoS2 QDs with a density of 1011 cm-2 and shows potential advantages for the fabrication of a wide range of electrical optical devices using QDs.