物理学报2017，Vol.66Issue(5)：166-173,8.DOI:10.7498/aps.66.054211
SiO2薄膜红外波段介电常数谱的高斯振子模型研究
Gaussian oscillator model of the dielectric constant of SiO2 thin film in infrared range
摘要
Abstract
SiO2 thin film is one of the most important low refractive index materials in the area of optical thin films. It is always used in the design and preparation of many kinds of multilayer films. The dielectric constant of the SiO2 thin film is a key characteristic for design of the multilayer thin film. The composite Gaussian oscillator model is one of the most important dispersion models for the dielectric constant of the amorphous SiO2 in the anomalous dispersion regime in the infrared range. More and more researchers have focused on the number and the physical meaning of the oscillators in the composite oscillator. A method to determine the SiO2 thin film oscillator quantity was proposed. In this method, the quantity of oscillator peaks was equivalent to the oscillator number of chemical composition, based on the factor analysis technology of chemometrics. Concretely, the composite oscillators of the dielectric constant were equivalent to the mixture, and the independent oscillators were equivalent to the compositions of the mixture. The absorbance of the mixture changed with the physical thickness of the thin film. Eight SiO2 film samples with different thickness were prepared on the Si substrate by the ion beam sputtering deposition. The infrared transmittances of the eight samples were used as elements in the spectral matrix. There were nine Gaussian oscillators in the range of 400–4000 cm?1, which was determined by the factor analysis technology. The dielectric constant of the SiO2 thin film in this range was obtained by the inverse calculation from the spectral transmittance. It provides the inverse calculation result for the dielectric constant of the SiO2 thin film with a specific physical meaning. By analyzing the dielectric constant in the range of 400–900 cm?1, the symmetric stretching vibrational frequency and the in-plane rocking frequency of the Si—O—Si bond of the SiO2 thin film can be obtained. Compared with fused silica, the symmetric stretching vibrational frequency increased while the rocking frequency was reduced. In fact, the frequency shifts are caused by the strain of the thin film. By analyzing the dielectric constant in the range of 900–1500 cm?1, four anti-symmetric stretching vibrational frequencies of the Si—O—Si bond in the SiO2 thin film were obtained. They have a certain corresponding relation with the anti-symmetric stretching vibrational frequency of the Si—O—Si bond in the fused silica. What's more, by analyzing the dielectric constant in the range of 3000–4000 cm?1, the water-cut (or hydroxyl) chemical defects in the films were confirmed. The chemical defects can influence the dielectric constant in the whole infrared range.关键词
SiO2薄膜/因子分析/高斯振子模型/红外波段介电常数Key words
SiO2 thin films/factor analysis/Gaussian oscillator model/dielectric constant in infrared range引用本文复制引用
刘华松,杨霄,王利栓,姜承慧,刘丹丹,季一勤,张锋,陈德应..SiO2薄膜红外波段介电常数谱的高斯振子模型研究[J].物理学报,2017,66(5):166-173,8.基金项目
国家自然科学基金(批准号:61405145, 61235011)、天津市自然科学基金(批准号:15JCZDJC31900)和中国博士后科学基金(批准号:2014M560104, 2015T80115)资助的课题. Project supported by the National Natural Science Foundation of China (Grant Nos. 61405145, 61235011), the Natural Science Foundation of Tianjin (Grant No. 15JCZDJC31900), and the China Postdoctoral Science Foundation (Grant Nos. 2014M560104, 2015T80115). （批准号:61405145, 61235011）
