Abstract:
Silicon dioxide (SiO
2) is one of the most widely used in various optical system as film material. The micro-structure and defects of SiO
2 films are of great importance to the functions and performance of these optical systems. In this paper, the absorption edge characteristics of single layer SiO
2 films prepared by electron beam evaporation, ion assisted deposition, and magnetron sputtering are investigated in detail via calculating their absorption edge spectrum, which is divided into three regions: the strong absorption, exponential absorption, and weak absorption regions. The bandgap, Urbach tail, and concentration of oxygen deficiency centers (ODC) are obtained by analyzing the measured absorption spectrum. By analyzing the bandgap, Urbach tail, and ODC data of SiO
2 films prepared with different deposition techniques and annealed at different temperatures, the atomic arrangement as well as micro-defect information of SiO
2 films are obtained and compared. Such information of SiO
2 films are important to the preparation of high-performance optical coatings employing SiO
2 as the low refractive index material.