Wafer-sized WS monolayer deposition by sputtering

We demonstrate that tungsten disulphide (WS 2 ) with thicknesses ranging from monolayer (ML) to several monolayers can be grown on SiO 2 /Si, Si, and Al 2 O 3 by pulsed direct current-sputtering. The presence of high quality monolayer and multilayered WS 2 on the substrates is confirmed by Raman spectroscopy since the peak separations between the A 1g -E 2g and A 1g -2LA vibration modes exhibit a gradual increase depending on the number of layers. X-ray diffraction confirms a textured (001) growth of WS 2 films. The surface roughness measured with atomic force microscopy is between 1.5 and 3 Å for the ML films. The chemical composition WS x ( x = 2.03 ± 0.05) was determined from X-ray Photoelectron Spectroscopy. Transmission electron microscopy was performed on a multilayer film to show the 2D layered structure. A unique method for growing 2D layers directly by sputtering opens up the way for designing 2D materials and batch production of high-uniformity and high-quality (stochiometric, large grain sizes, flatness) WS 2 films, which will advance their practical applications in various fields. Radio frequency sputtering by argon ions on a target consisting of tungsten disulphide can create a single layer of the compound on a 4′′ Si-wafer with one W atom per two S atoms when including hydrogen sulphide in the sputtering atmosphere.