SiO_2光学薄膜的吸收边特性

Characterictics of absorption edge of SiO_2 films

二氧化硅(SiO_2)是光学系统中最常用光学薄膜材料之一,其微观结构、缺陷等信息对于研究和提高薄膜的性能具有重要作用。本文通过电子束蒸发、离子辅助、磁控溅射方法制备SiO_2薄膜并进行测试,计算出其吸收边光谱,对吸收边光谱的强吸收区、e指数区、弱吸收区进行分段分析得到SiO_2薄膜的带隙宽度、带尾能量和氧空位缺陷含量数据。进一步分析三种薄膜和其在常规退火温度下的带隙宽度、带尾能量和氧空位缺陷含量的数据,获得SiO_2薄膜的微观原子排列结构、微观缺陷信息,并对不同镀膜技术和不同退火温度下SiO_2薄膜的原子排列结构、微观缺陷的差异和变化进行了分析和讨论。

Silicon dioxide(SiO2) is one of the most widely used in various optical system as film material. The micro-structure and defects of SiO2 films are of great importance to the functions and performance of these optical systems. In this paper, the absorption edge characteristics of single layer SiO2 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 SiO2 films prepared with different deposition techniques and annealed at different temperatures, the atomic arrangement as well as micro-defect information of SiO2 films are obtained and compared. Such information of SiO2 films are important to the preparation of high-performance optical coatings employing SiO2 as the low refractive index material.