Preparation and Field-effect Mobility of Nb Doped MoS2 Nano-films on SiO2 Substrate

In this study, large-area growth of Nb-MoS2 layers on SiO2 substrates using one-pot chemical vapor deposition via two steps was successfully achieved. For the first time, a facile, cost-effective and mass-scalable direct synthesis approach was designed for doping Nb into MoS2 layers using MoO3, sulfur (S) and NbCl5 as precursors. The proposed process allowed retaining the uniformity of large area thin layers which are sui-table for device fabrication. The structural and optical properties of the resulting Nb-MoS2 layers were systematically investigated. Scanning electron microscope (SEM), atomic force microscope (AFM), Raman, photoluminescence (PL) spectra and X-ray photoelectron spectroscopy (XPS) analyses confirmed the formation of continuous and crystalline few-layers MoS2 and Nb-MoS2. An obvious blue-shift of up to 90 meV in photoluminescence peaks was observed for samples with different grain sizes. The electrical properties of the as-prepared materials were evaluated by bottom-gate FETs. A field-effect mobility of 1.22 cm2•V-1•s-1 and a current on/off ratio of 105 were obtained. In particular, Nb-MoS2 prepared by Nb doping greatly reduced the resistance of the film to 66.67 kΩ. These findings provide a novel route towards scaled-up synthesis of high-quality few-layered MoS2 by transition-metal doping in TMDCs which are suitable for electronic and optoelectronic devices. © 2019, Materials Review Magazine. All right reserved.