Multilayer systems of alternating chalcogenide As-Se and polymer thin films prepared using thermal evaporation and spin-coating techniques

We describe preparation and characterization of multilayer planar systems based on alternating chalcogenide As-Se and polymer polyamide-imide (PAT) or polyvinyl- buty ra I (PVB) thin films. We deposited films of thermally evaporated AS(33)Se(67) chalcogenide glass periodically alternating with PAT or PVB films. Fifteen layers of As - Se + PAT system and 17 layers of As - Se + PVB system were deposited. The film thicknesses were approximately 100 run for all of the film types. Polymer film thicknesses were calculated from profilometric measurements performed by an atomic force microscopy. Optical properties of prepared multilayers and also As-Se, PAT and PVB single layers were established using UV-vis-NIR and ellipsometric spectroscopies. Both, As-Se + PAI and As-Se + PVB multilayer systems, exhibited the reflection (stop) bands centered near 830nm. The bandwidth of reflection band of As-Se+PAI multilayer was 90 nm while bandwidth of As-Se + PVB system increased to 150 nin because PVB films had about 0.2 lower refractive index. A new possibility for the application of chalcogenide thin films appeared as high refractive index materials suitable for fabrication of optical elements (reflectors) for near-infrared region. Changing the films composition and thickness, multilayer systems with tailored position of stop band could be designed and prepared. (c) 2007 Elsevier Ltd. All rights reserved.