Properties of the YbF₃ Films Prepared by Ion-Assisted Deposition

The purpose of this study is to characterize the microstructure, composition, optical properties and residual stress of YbF3 films. The films were deposited by ion-assisted deposition at different ion energy. The SEM images showed that the surface of the film was uniform and smooth. The XRD patterns showed that the YbF3 films presented an amorphous microstructure. XPS measurement revealed that the ratio of F and Yb reduced with increasing ion energy. The optical constants of the films were determined from the whole optical spectrum. The refractive index increased with the ion energy. Due to the decrease in the amount of F, non-stoichiometric films were formed, and the visible light absorption of the films increased with increasing ion energy. Higher ion energy could increase the packing density, resulting in a decrease in the moisture absorption of the film. The films exhibited tensile stress. The value of residual stress increased with increasing ion energy, since moisture adsorption had an important effect on the residual stress.