Figure 5
From: Synthesis, properties and potential applications of two-dimensional transition metal dichalcogenides
Sulfurization (or selenization) of metal (or metal oxide) thin film. (a) Schematic ilustration for the synthesis of MoS2 layers by MoO3 sulfurization. A layer of MoO3 (3.6Â nm) was thermally evaporated on the sapphire substrate. The MoO3 was then converted to MoS2 by a two-step thermal process [63]. (b) MoS2 layer grown on a sapphire wafer [63]. (c) X-Ray photoemission spectroscopy (XPS) results for Mo and S binding energies of the MoO3 layer before and after sulfurization. Raman (lower left) and PL spectra (lower right) for the obtained MoS2 trilayer after MoO3 sulfurization [63]. (d) Synthesis procedure for the ALD-based WS2 nanosheets [65]. (e) OM images of the transferred WS2 nanosheet on the SiO2 substrate for the single-, bi-, and tetralayered thicknesses [65]. (f) AFM images and height profiles (inset) of the WS2 nanosheet transferred onto the SiO2 substrate for the single-, bi-, and tetralayered thicknesses [65]. (g) Raman spectra for the single- (red), bi- (blue), and tetralayer (black) WS2 nanosheets on SiO2 substrates [65]. (h) Relative Raman peak intensities (red) and peak distances (blue) of the E1 2g and A1g bands for the single-, bi-, and tetralayer WS2 nanosheets [65]. (i) PL spectra for the single- (red), bi- (blue), and tetralayer (black) WS2 nanosheets on SiO2 substrates [65]. (j) XPS measurements for the W4f (red) and S2p (blue) core levels of the single-layer WS2 nanosheet [65].