The structure and optical properties of amorphous thin films along the As40S60 - MoS3 tie-line prepared by spin-coating

• Published in: Materials research bulletin 2022-09, Vol.153, Article 111871
• Main Authors: Krbal, M., Prokop, V., Cervinka, V., Slang, S., Frumarova, B., Mistrik, J., Provotorov, P., Vlcek, M., Kolobov, A.V.
• Format: Article
• Language: English
• Subjects: Chalcogenides; formula omitted; Optical properties; Spin-coating; Structure; Thin films
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2022.111871

•A facile preparation of amorphous As40S60 thin films modified by MoS3.•Transparent and smooth amorphous thin films up to a molar ratio of 1As40S60 : 3MoS3.•MoS3 enhances the thermal stability of amorphous As40S60 thin films.•As MoS3 increases, the refractive index decreases and absorption tails appear.•As40S60 and MoS3 are reacted chemically already in solutions. [Display omitted] The extremely high melting point of Mo, W and their sulfides acts as a barrier to the synthesis of chalcogenide glasses modified with these transition metal elements. Here, we demonstrate the preparation of amorphous thin films along the pseudobinary As40S60 - MoS3 tie-line by spin-coating. Using 0.02 M stock solutions, the limiting As40S60 : MoS3 molar ratio was found to be 1 : 3 for the deposition of highly transparent, very smooth and compact defect-free amorphous thin films. The spectral analysis of optical constants revealed that both the refractive index and extinction coefficient decrease with increasing MoS3 content. On the other hand, the contribution of absorption tails was observed starting from the ratio 2 : 1 and they gradually become more intense and red-shifted with increasing MoS3. Using Raman and infrared spectroscopies (ATR), we confirmed that As40S60 and MoS3 reacted chemically in solution and all thin layers contained only residual amounts of organic ammonium salts after annealing at 200∘C. Our results demonstrate that the sol-gel method can be a feasible and cost-effective strategy for the preparation of amorphous chalcogenide thin films containing transition metals.