Optical constant of SiOx films in mid-IR range prepared by ion-assisted deposition

SiO x (x~1) films were prepared by the ion-assisted deposition (IAD) process. The films were evaporated from silicon monoxide with and without simultaneous Ar + bombardment. As analyzed by using X-ray diffraction and transmission electron microscopy measurements, the films showed amorphous structures. The stoichiometry of each film was determined by using both infrared spectrometry and X-ray photoelectron spectrometry. The results revealed that the oxygen content of the SiO x thin films was slightly varied under the different conditions of Ar+ bombardment. The optical constants of the SiO x thin films in the mid-infrared range were measured using an infrared variable angle spectroscopic ellipsometer. The variation of these refracting indices was mainly related to the packing density. The results presented in this work showed the possibilities of controlling the stoichiometry and the refracting index of the SiO x thin film by the application of IAD process.