Rezumate Simpozion 2006 - ICECHIM

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3. NEW HYBRID COMPOSITE FILMS BASED ON PVA-As 2 S 3 AND
ITS PHYSICAL PROPERTIES
Alexei Meshalkin, Andrei Andries, Valeriu Bivol, Svetlana Buzurniuc, Victor Verlan
Center of Optoelectronics of Institute of Applied Physics, Academy of Sciences of Moldova
1 Academiei St., MD-2028, Chisinau, Moldova Republic. E-mail: alexei@as.md
Thin films of chalcogenide glasses have been investigated by numerous authors. Films
of chalcogenides have been mainly deposited onto the substrate using vacuum coating
techniques, i.e., thermal evaporation, sputtering or laser ablation. Various techniques such as
hydrolysis, chemical vapor deposition and laser deposition have been introduced to fabricate
hybrid composite materials. Now the new possibilities to obtain composite materials based on
chalcogenide glasses and polymer have been appeared 1,2 . Composites, based on polymer, such
as Polyvinyl Alcohol (PVA), and on arsenic sulfide As 2 S 3 were successfully synthesized by
the sol-gel process. Thin films of this composite were deposited on different substrates such
as optical glass, polyethyleneterephthalate and monocrystallic silicon wafer by spin-coating
technique.
The samples were obtained with the thickness in the range of 0,6 µm to 4 µm. The
content of As 2 S 3 was maintained within the limit of 1 – 90 wt.% of the polymer PVA. The
variations of the concentration of As 2 S 3 and the transmission spectra were studied for
determination of optical band gap. It was shown that the absorption edge was shifted to the
short wavelength side with decreasing of the As 2 S 3 component in the composite.
Beginning from the concentration of 6-10 wt.% and more the optical gap was the same as
vacuum evaporated film of As 2 S 3 and it was equal to 2,4 ± 0,05 eV. This coincides with
literature data for optical gap of films and bulk samples of As 2 S 3 . It means that molecular
structure of dissolved chalcogenide substance in polymer remains the same as in pure initial
chalcogenide. This conclusion is also confirmed by the absorption spectra on each stage of
preparation of polymer composite. Also optical properties dependence on UV-light exposure
was investigated. It was proved that new composite are sensitive to light irradiation and the
actinic light leads to change the refractive index at the rate 0,1. The investigated new
composite films are perspective for different photonic devices as well as for recording media
with high resolution.
1. A.Andries, V.Bivol, A.Prisacar, S.Sergheev, A.Meshalkin, S.Robu, N.Barba, N.Sirbu, J. Optoelectron. Adv.
Mater, Vol.7, No.3, 2005, p.1169-1178.