Abstract
Amorphous oxide thin films consisting of SiO 2 /Ta 2 O 5 multilayers with high-reflectance as well as low-loss quality were grown on a glass substrate by ion beam sputtering. Using both the rotating anode and synchrotron radiation x-rays, we have characterized the thickness and density of the thin layers and the interface roughness from the x-ray reflectivity profiles. Measurement data showed that the deviation of the nominal layer thickness was controlled within 1%, and the root-mean-square roughness was in the range of 0.3 nm, which is compatible with the images obtained by atomic force microscopy. The best performance for the total loss of Ta 2 O 5 /(SiO 2 /Ta 2 O 5 ) 17 multilayer at a wavelength of 632.8 nm was 86 PPM. Concerning possible impurities contained in the coating layers, the total reflection x-ray fluorescence spectra showed that the major 3d-element contamination of the films within the minimum detection limit of this work, 6×10 10 atoms/cm 2 , was Fe.