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

Abstract

We describe preparation and characterization of multilayer planar systems based on alternating chalcogenide As–Se and polymer polyamide-imide (PAI) or polyvinyl-butyral (PVB) thin films. We deposited films of thermally evaporated As 33 Se 67 chalcogenide glass periodically alternating with PAI or PVB films. Fifteen layers of As – Se + PAI system and 17 layers of As – Se + PVB system were deposited. The film thicknesses were approximately 100 nm 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, PAI 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 830 nm. The bandwidth of reflection band of As – Se + PAI multilayer was 90 nm while bandwidth of As – Se + PVB system increased to 150 nm 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.