Argon and Other Defects in Amorphous SiO2 Coatings for Gravitational-Wave Detectors

Amorphous SiO2 thin films are one of the two components highly reflective mirror coatings gravitational-wave detectors. For this study, layers amorphous on crystalline Si substrates were produced by ion-beam sputtering (IBS), using accelerated neutralized argon ions as particles, is case for actual The aim study to investigate possible presence various defects in materials order improve coating quality. We provide evidence that, due synthesis method, about 0.2 wt.% Ar present coatings, and it can be released means thermal treatments, starting around 400 °C. time temperature obtain total release increases with thickness; a thickness 100 nm, all below 600 °C, while an isotherm hour at 900 °C necessary 5 μm thick. Besides atoms left from synthesis, other defects, such clusters silicon dangling bonds, coatings. concentration both them strongly reduced treatments either vacuum or air. overall slightly increased after witnessed change period interference fringes.