The comparison of Ag-As33S67 films prepared by thermal evaporation (TE), spin-coating (SC) and a pulsed laser deposition (PLD)

Chalcogenide thin films could be prepared by many experimental methods resulting in some differences in structure and physicochemical properties of prepared films. In this work, the As33S67 amorphous films were prepared by three different preparation techniques: vacuum thermal evaporation (TE), pulsed laser deposition (PLD) and spin-coating (SC). A silver film was deposited on the top of the As33S67 films and photodoped. The X-ray diffraction analysis showed significant differences in arrangement between bulk glass and thin films and also among films themselves. The Raman spectroscopy showed that the Raman spectra of PLD film and bulk glass are almost similar. On the other hand, TE films contain higher amount of homopolar bonds As-As and S-S. The value of refractive index of As33S67 bulk glass was 2.31. All prepared films have lower index of refraction contrary to bulk glass, i.e. TE similar to 2.27, PLD similar to 2.20 and SC similar to 1.90. The increase of refractive index with silver concentration is shown either. The optical bandgap of undoped As-S prepared films was different: TE similar to 2.42eV, PLD similar to 2.45 eV and SC similar to 2.54 eV. (c) 2007 Published by Elsevier Ltd.