Chemical Vapor Deposition of NbS2 from a Chloride Source with H2 Flow: Orientation Control of Ultrathin Crystals Directly Grown on SiO2/Si Substrate and Charge Density Wave Transition

This article reports the growth and characterization of z-axis-oriented NbS2 thin films on SiO2/Si substrate by ambient pressure chemical vapor deposition (CVD) using a generic metal chloride source. We found that NbS2 nanosheets can be grown directly on the SiO2/Si substrate with the aid of hydrogen gas mixed in the carrier gas. Detailed examination Of the growth parameters was made possible using a separate-flow CVD apparatus. It appears that the major cause of the misorientation is the off-stoichiometry with surplus Nb. The quality of the films was evaluated by X-ray diffraction and Raman spectroscopy as well as resistivity measurements at low temperatures. They showed a resistivity minimum at the same temperature of the charge density wave (CDW) transition for a bulk single crystal of 3R-NbS2.