Preparation of dielectric mirrors from high-refractive index contrast amorphous chalcogenide films

摘要

We report the preparation of planar 15-layer dielectric mirrors by a thermal evaporation of alternating high refractive index contrast amorphous chalcogenide Sb-Se and Ge-S layers, exhibiting a high-reflection band around 1.55 mu m. The layer deposition quality and the thickness accuracy of such prepared chalcogenide multilayers were then checked using transmission electron microscopy. The layer thickness deviation of chalcogenide layers did not exceed similar to 7 nm in comparison with the desired thicknesses. The width of Sb-Se/Ge-S layer boundary was approximately similar to 3nm, which is in good agreement with the surface roughness values of thermally evaporated Sb-Se and Ge-S single layers. The optical properties of the prepared 15-layer dielectric mirrors were consistent in temperature range of 20-120 degrees C; however, at higher temperatures there started apparent structural changes of Sb-Se films, which were followed by their crystallization. Excellent optical properties of chalcogenide materials in the infrared range make them interesting for applications, e.g., in optics and photonics. (c) 2008 Elsevier Ltd. All rights reserved.