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

• Main Authors: Anna Łapińska, Michał Kuźniewicz, Arkadiusz P. Gertych, Karolina Czerniak-Łosiewicz, Klaudia Żerańska-Chudek, Anna Wróblewska, Michał Świniarski, Anna Dużyńska, Jarosław Judek, Mariusz Zdrojek
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Materials
• Subjects: WS₂; tungsten disulfide; thin film; Transition Metal Dichalcogenides (TMDC); Raman spectroscopy; electrical properties
• Online Access: https://www.mdpi.com/1996-1944/13/23/5315

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 R_S = 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.