Study of Structural and Optoelectronic Properties of Thin Films Made of a Few Layered WS2 Flakes

Abstract

We report a surfactant-free exfoliation method of WS2 flakes combined with a vacuum filtration method to fabricate thin (<50 nm) WS2 films, that can be transferred on any arbitrary substrate. Films are composed of thin (<4 nm) single flakes, forming a large size uniform film, verified by AFM and SEM. Using statistical phonons investigation, we demonstrate structural quality and uniformity of the film sample and we provide first-order temperature coefficient χ, which shows linear dependence over 300–450 K temperature range. Electrical measurements show film sheet resistance RS = 48 MΩ/Υ and also reveal two energy band gaps related to the intrinsic architecture of the thin film. Finally, we show that optical transmission/absorption is rich above the bandgap exhibiting several excitonic resonances, and nearly feature-less below the bandgap.

Apparent Colors of 2D Materials

“…[ 86 ] However, it also features intriguing properties when it is studied in few layers, paving a way in electronics, optoelectronics, photovoltaics, and thermoelectricity applications. [ 87–89 ]…”

“…[86] However, it also features intriguing properties when it is studied in few layers, paving a way in electronics, optoelectronics, photovoltaics, and thermoelectricity applications. [87][88][89] Figure 7 shows WS 2 flakes deposited onto three different Si substrates with SiO 2 capping layers of 88, 215, and 297 nm, [2] Copyright 2013, American Chemical Society. b) Color optical images of 1LÀ15L MoS 2 on 300 nm SiO 2 /Si substrate.…”

Stable and tunable multi-wavelength erbium-doped fiber lasers using saturable absorbent tungsten disulfide

“…It was proved that a few layered tungsten disulfides had larger energy gap widths and light absorption capacity. This study provides theoretical support for a WS 2 film as a saturable absorber [23]. Compared with other methods for suppressing mode competition, the WS 2 film is low cost and can be easily adsorbed on the end face of the fiber in the lasers.…”

Morphology Control of WS2 Nanoflakes Using Chemical Vapor Deposition for Improving the Photocatalytic Activity of the WS2/TiO2 Heterostructure

“…For instance, the layer-dependent band gap of WS 2 can be tuned from an (1.3 eV) indirect band gap in the bulk to a (2.1 eV) direct band gap in a single layer. Furthermore, as a 2D material, WS 2 has a high specific area with an abundance of active sites and superior electrical conductivity. − According to these features, WS 2 can be nominated to have good catalytic performance.…”