Layered WS2 thin films prepared by sulfurization of sputtered W films

• DOI: 10.1016/j.apsusc.2020.148719
• Publication Date: 2021-01-08T02:53:09Z
• Authors: I. Hotovy; L. Spiess; M. Mikolasek; I. Kostic; M. Sojkova; H. Romanus; M. Hulman; D. Buc; V. Rehacek
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract We present structural, optical and electrical investigations of layered WS2 films prepared on tungsten. A two-step technique has been used to synthesize layered WS2 films using sulfurization of W films sputtered with thinner (1 and 2 nm) and thicker (14 and 28 nm) thicknesses at 800 °C. XRD analysis revealed that the examined films are polycrystalline with texture and have a 2H-WS2 hexagonal microstructure. Using Raman spectroscopy with the 532 nm laser excitation, the presence of E12g and A1g vibration modes was observed and the layered nature of WS2 was confirmed. FE SEM observations showed two different surface morphologies. The samples grown on thinner W films were not compact over the surface and agglomeration of nanosize grains in combination of triangles and flakes was visible. In another group the surface was lamellar and contained plenty of nanorods embedded vertically and/or inclined at different angles to the surface. Layered WS2 films exhibited a direct band gap in the range of 2.1–2.5 eV and they were n-type semiconductors with the sheet resistance in the order of several MΩ at room temperature.