表面等离子共振效应中传统近似理论与薄膜光学理论

指出Kretschmann模型的传统表面等离子共振公式在求解金属薄膜的参量时存在近似性,采用更为严密的薄膜光学理论,通过薄膜膜系的特征矩阵,得出表面等离子体共振衰减曲线.结果表明,表面等离子体共振近似理论与薄膜光学理论得到的共振角及反射率幅度存在差别;采用等高线图,给出了共振角差随着金属介电常量的变化规律.进一步的实验表明,薄膜光学理论所得模拟结果较表面等离子体共振近似理论与实验值吻合地更好,证明薄膜光学理论应用在表面等离子体共振效应要优于常用的近似理论.最后,采用两种理论对表面等离子体共振传感器进行优化设计,结果表明,两种理论所获得的高灵敏度分布区域差异较大,必须采用薄膜光学理论提供更精确的薄膜参量,来优化设计高灵敏度表面等离子体共振传感器.     

表面等离子共振效应中传统近似理论与薄膜光学理论

指出Kretschmann模型的传统表面等离子共振公式在求解金属薄膜的参量时存在近似性,采用更为严密的薄膜光学理论,通过薄膜膜系的特征矩阵,得出表面等离子体共振衰减曲线.结果表明,表面等离子体共振近似理论与薄膜光学理论得到的共振角及反射率幅度存在差别;采用等高线图,给出了共振角差随着金属介电常量的变化规律.进一步的实验表明,薄膜光学理论所得模拟结果较表面等离子体共振近似理论与实验值吻合地更好,证明薄膜光学理论应用在表面等离子体共振效应要优于常用的近似理论.最后,采用两种理论对表面等离子体共振传感器进行优化设计,结果表明,两种理论所获得的高灵敏度分布区域差异较大,必须采用薄膜光学理论提供更精确的薄膜参量,来优化设计高灵敏度表面等离子体共振传感器.     

利用辐射计测量半透薄膜的光学特性

随着光电技术的发展,各种光学半透明薄膜在实际中得到了广泛应用。光学薄膜的使用必须建立在光学特性(如透射率、反射率和吸收率)已知的基础之上。一般而言,对于半透薄膜透射率的测量比较简单,而对于反射率和吸收率的测量往往比较复杂。本文在总结前人研究薄膜光学特性测量经验的基础之上,通过分析光路在多层薄膜间的传递过程,设计了一种利用辐射计有效测量半透薄膜光学特性的方法,测量简便、快速,可直接得到测量波段内薄膜的半球光学特性参数。在待测薄膜光学特性比较极端(透射率、反射率和吸收率其中之一很大或者很小)时,该方法仍然能够进行测量,并且透射率和反射率测量可苇复性好,相对偏差一般不超过6%。     

碳纳米管薄膜周期结构的太赫兹表面等离子波特性研究

在获得太赫兹波段碳纳米管薄膜的介电特性基础上,利用数值THz时域光谱技术研究了碳纳米管薄膜栅周期结构的表面等离子激元的传播特性和局域化现象. 研究结果表明,在栅周期为168 μm时,频率在0.5-2.5 THz之间出现两个等离子模式的共振峰值,分别位于0.99 THz和1.95 THz,这与理论计算结果相符合. 数值计算的表面等离子激元传播距离与理论预测值相一致,达到了146 μm. 此外,分析了栅厚度与栅宽度变化对表面等离子波特性的影响. 关键词： 太赫兹 碳纳米管 表面等离子波     

基于双电介质层的棱镜表面等离子共振传感的研究

为了提高表面等离子共振系统的分辨率,提出了一种五层结构的表面等离子共振效应的激励模型:棱镜基底-银膜-电介质层1-电介质层2-待测介质.采用薄膜光学和波导理论,讨论了银和双电介质层复合而成的共振薄膜对表面等离子共振效应的激励机理与调制特性的作用.借助有限元分析方法,数值模拟得到双电介质表面等离子共振激励模型的共振光谱.分析结果表明,当待测介质折射率相同时,双电介质表面等离子共振激励模型共振光谱的半峰宽约为传统棱镜表面等离子体共振的0.1倍,理论计算得到双电介质表面等离子共振激励模型的系统分辨率相较于传统棱镜表面提高了5.4倍.以乙二醇溶液为待测样本,分析得到传感器的灵敏度约为7.2°/RIU,品质因数约为465,证明了该结构设计的可行性,为设计高分辨率和高品质因数的传感系统提供了理论参考.     

热丝CVD生长金刚石薄膜研究

本文研究了热丝CVD方法生长金刚石薄膜过程中,衬底表面的损伤处理对金刚石薄膜光学性能的影响,以及膜中非本征杂质吸收对其红外光学特性的影响。     

降低表面等离子激元寄生吸收损失的途径研究

从纳米Ag颗粒表面等离子激元光学及表面高能电场特性两方面入手,较为系统地研究了周围介质的导电特性对表面等离子激元的影响.通过对复合薄膜紫外-可见-近红外光谱及表面增强拉曼散射光谱的分析,指出绝缘性的Al₂O₃介质薄膜能够起到良好的表面电场定域效果,且不会引入附加的光吸收损失;而导电性的ITO薄膜则会引入表面价电子的溢出损失,加速了表面电场的衰逝,同时引起长波方向上显著的光吸收损失.研究还表明致密的Al₂O₃介质薄膜能够起到良好的屏蔽作用,且纳米Ag颗粒表面等离子激元特性仅受最近邻材料特性的影响.研究结果为在硅基薄膜太阳电池中实现对纳米Ag颗粒的阻挡、寄生光吸收损失的降低以及表面高能电场的利用,提供了一条有效的解决途径.     

用双介质法测定金属薄膜的厚度和光学常数

用角度扫描衰减全反射方法(ATR),激励金属和两种介质界面处的表面等离子激元波(SPW)通过这些表面等离子激元波和介质折射率的关系同时确定了金属薄膜的厚度和光学常数.实验结果和理论分析相符.     

表面电磁振荡激元波在光学薄膜研究中的应用(Ⅰ)

表面电磁振荡激元波(SPW)谐振是金属膜参数及其表面状态的十分灵敏的函数。因而利用SPW技术可以精确地确定金属膜及其表面污染层的光学常数。本文利用经典的薄膜光学方法讨论了SPW的激发及其理论计算。并在Kretschmann装置上测量了SPW谐振反射率,借助于最优化技术计算了薄膜和表面层的光学常数。最后给出了Ag、Au、Cu和Al膜及以诸如Ag_2S、CuO_x和Al_2O_3等表面层的实验结果。     

椭偏光谱测量中椭偏参数的灵敏度分析

在对椭圆偏振测量的基本原理进行了简单介绍和推导后,讨论了椭圆偏振测量中椭偏参数关于薄膜参数的灵敏度以及入射角对椭偏参数的影响,并进行了具体的仿真分析,得到如下结论：椭偏参数Delta对薄膜光学常数和薄膜厚度变化的灵敏度明显高于椭偏参数Psi。在椭偏数据处理中,椭偏参数Delta的测量精度直接影响薄膜光学常数和薄膜厚度的拟合精度。为了提高椭偏参数Delta的测量精度,可以选择入射角在膺布儒斯特角附近。所得结论对高精度椭偏测量具有指导意义。     

Rapid determination of surface roughness of polycrystalline silicon following frontside and backside excimer laser irradiation

Excimer-laser crystallization (ELC) is the most commonly employed technology for fabricating low-temperature polycrystalline silicon (LTPS). Investigations on the surface roughness of polycrystalline silicon (poly-Si) thin films have become an important issue because the surface roughness of poly-Si thin films is widely believed to be related to its electrical characteristics. In this study, we develop a simple optical measurement system for rapid surface roughness measurements of poly-Si thin films fabricated by frontside ELC and backside ELC. We find that the incident angle of 20° is a good candidate for measuring the surface roughness of poly-Si thin films. The surface roughness of polycrystalline silicon thin films can be determined rapidly from the reflected peak power density measured by the optical system developed using the prediction equation. The maximum measurement error rate of the optical measurement system developed is less than 9.71%. The savings in measurement time of the surface roughness of poly-Si thin films is up to 83%. The method of backside ELC is suggested for batch production of low-temperature polycrystalline silicon thin-film transistors due to the lower surface roughness of poly-Si films and higher laser-beam utilization efficiency.     

A new method to characterizing surface roughness of TiO2 thin films

Titanium dioxide (TiO₂) thin films have been widely coated in the self-cleaning glass for facade application. The benefit of these glasses is its ability to actively decompose organic compounds with the help of ultraviolet light. Understanding the surface roughness of TiO₂ thin films is important before manufacturing of self-cleaning glasses using TiO₂ thin films because surface roughness of TiO₂ thin films has highly significant influence on the photocatalytic performance. Traditional approach for measuring surface roughness of TiO₂ thin films is atomic force microscopy. The disadvantage of this approach include long lead-time and slow measurement speed. To solve this problem, an optical inspection system for rapidly measuring the surface roughness of TiO₂ thin films is developed in this study. It is found that the incident angle of 60° is a good candidate for measuring surface roughness of TiO₂ thin films and y=90.391x+0.5123 is a trend equation for predicting the surface roughness of TiO₂ thin films. Roughness average (Ra) of TiO₂ thin films (y) can be directly determined from the peak power density (x) using the optical inspection system developed. The results were verified by white-light interferometer. The measurement error rate of the optical inspection system developed can be controlled by about 8.8%. The saving in inspection time of the surface roughness of TiO₂ thin films is up to 83%.     

Rapid surface roughness measurements of silicone thin films with different thicknesses

A rapid optical measurement system for rapid surface roughness measurement of polycrystalline silicon (poly-Si) thin films was developed in this study. Two kinds of thickness of poly-Si thin films were used to study rapid surface roughness measurements. Six different incident angles were employed for measuring the surface roughness of poly-Si thin films. The results reveal that the incident angle of 20° was found to be a good candidate for measuring the surface roughness of poly-Si thin films. Surface roughness (y) of poly-Si thin films can be determined rapidly from the average value of reflected peak power density (x) measured by the optical system developed using the trend equation of y = ?0.1876x + 1.4067. The maximum measurement error rate of the optical measurement system developed was less than 8.61%. The savings in measurement time of the surface roughness of poly-Si thin films was up to 83%.     

10.6μm激光辐照下光学薄膜的微弱吸收测量

 建立了表面热透镜技术测量光学薄膜微弱吸收的实验装置，对10.6μm CO₂激光辐照下镀制在Ge基底上的不同厚度的单层ZnS，YbF₃薄膜，以及镀制在Ge基底上不同膜系的（YbF₃/ZnSe）多层分光膜的弱吸收进行了测量，并对实验结果作了分析和讨论。实验结果表明，利用本实验系统已测得的待测样品的最低吸收为2.87×10^-4，测量系统的灵敏度为10^-5。     

10.6μm激光辐照下光学薄膜的微弱吸收测量

建立了表面热透镜技术测量光学薄膜微弱吸收的实验装置,对10.6μm CO2激光辐照下镀制在Ge基底上的不同厚度的单层ZnS,YbF3薄膜,以及镀制在Ge基底上不同膜系的（YbF3/ZnSe）多层分光膜的弱吸收进行了测量,并对实验结果作了分析和讨论。实验结果表明,利用本实验系统已测得的待测样品的最低吸收为2.87×10-4,测量系统的灵敏度为10-5。     

Regrowth of ZnO thin film with high surface flatness and enhanced optical properties on annealed buffer layers by rf sputtering deposition

We report a study on improving the surface flatness, optical properties, and crystallinity of ZnO thin films by rf sputtering deposition. ZnO thin films grown on sapphire substrate were first exposed to post-growth annealing, and then used to regrow high-quality ZnO thin films on top. Under the same deposition conditions, the regrown ZnO layers showed much improved crystallinity, surface flatness and enhanced optical properties. The effect of the annealed layer in improving the quality of the ZnO thin film is discussed in terms of characterization results from crystal orientation, surface morphology, and photoluminescence. It was clearly observed that, during the annealing process, the ZnO grains coalesced to form larger grains and smoother surfaces, with better crystallinity and fewer defects, which resulted in the much improved quality of the regrown ZnO thin films.     

Characterization of poly (3-methyl thiophene) thin films prepared by modified chemical bath deposition

Poly (3-methyl thiophene) thin films were prepared by chemical bath deposition technique on glass substrate; the prepared thin films were characterized for structural, morphological and optical properties. The variation in the oxidant concentration has an influence on the properties of the P3MeT thin films. The increase in the oxidant concentration leads to increase in the thickness of the film. The binding energy increases due to increase in oxidation concentration. The P3MeT thin films show smooth surface morphology with increase in oxidant concentration whereas the contact angle of the thin film decreases with increase in oxidant concentration. The optical absorbance of these thin films was found to increase with decrease in the optical band gap due to increase in oxidant concentration.     

银薄膜对光学基底表面粗糙度及光散射的影响

为了研究金属银薄膜与光学基底表面粗糙度和光散射的关系,提出了通过对光学薄膜矢量散射公式积分来获得界面粗糙度完全相关模型和完全非相关模型下其表面的总反射散射的方法.理论计算了光学基底上两种模型在不同厚度银膜下的总反射散射和双向反射分布函数.结果表明,当沉积在光学基底上的银薄膜的厚度大于80 nm后,两种模型下计算的银薄膜的表面总反射散射都等于基底的总积分散射,银薄膜能较好地复现出基底的粗糙度轮廓.实验研究表明为了复现基底的粗糙度,银薄膜的最佳厚度应在80~160 nm之间.     

SiO2和HfO2薄膜光学性能的椭偏光谱测量

结合XRD和原子力显微镜等方法,利用椭圆偏振光谱仪测试了单层SiO2薄膜（K9基片）和单层HfO2薄膜（K9基片）的椭偏参数,并用Sellmeier模型和Cauchy模型对两种薄膜进行拟合,获得了SiO2薄膜和HfO2薄膜在300-800nm波段内的色散关系。用X射线衍射仪确定薄膜结构,并用原子力显微镜观察薄膜的微观形貌,分析表明：SiO2薄膜晶相结构呈现无定型结构,HfO2薄膜的晶相结构呈现单斜相结构;薄膜光学常数的大小和薄膜的表面形貌有关;Sellmeier和Cauchy模型较好地描述了该波段内薄膜的光学性能,并得到薄膜的折射率和消光系数等光学常数随波长的变化规律。     

Rapid optical measurement of surface roughness of BiFeO<Subscript>3</Subscript> films for nonvolatile memory application

An optical inspection system for rapid surface roughness measurement of BiFeO₃ (BFO) thin films is developed. It is found that y = −121.45 x + 212.81 is a trend equation for characterizing the surface roughness of BFO thin films. The incident angle of 60◦ is a good candidate for measuring the surface roughness of BFO thin films. The maximum measurement error rate of the optical inspection system developed is less than 2.6%. The savings in inspection time of the surface roughness of BiFeO₃ thin films is up to 90%.