氢化非晶硅薄膜制备及其椭圆偏振光谱测试分析

射频磁控溅射法制备a-Si:H薄膜,利用椭圆偏振光谱对不同气压下a-Si:H薄膜的厚度、折射率和消光系数进行了测试和研究。薄膜采用双层光学模型,通过Forouhi-Bloomer模型对椭圆偏振光谱参数进行拟合,获得450-850 nm光谱区域的a-Si:H薄膜光学参数值。结果表明,随着工作气压增加,薄膜厚度增厚,沉积速率升高;相同工作气压下,随偏振光波长增大,折射率呈下降趋势;相同波长偏振光下,折射率随工作气压上升而下降,折射率变化范围在3.5-4.1;消光系数随着工作气压增大呈略微增大的趋势。根据吸收系数与消光系数的关系,获得了薄膜的吸收谱,测算出不同工作气压下a-Si:H薄膜的光学带隙为1.63 eV-1.77 eV。     

Ba0.9Sr0.1TiO3薄膜的椭偏光谱研究

用椭偏光谱仪首次在光子能量为2.15.2eV的范围内,测量了不同热处理温度下Ba0.9Sr0.1TiO3(BST)薄膜的椭偏光谱.建立适当的拟合模型,并用Cauchy色散模型描述BST薄膜的光学性质,用最优化法获得了所有样品的光学常数(折射率n和消光系数k)谱及禁带能Eg.比较这些结果,初步得到了BST薄膜的折射率n、消光系数k和禁带能Eg随退火温度变化的变化规律.     

Ba0.9Sr0.1TiO3薄膜的椭偏光谱研究

用椭偏光谱仪首次在光子能量为2．1－5．2eV的范围内,测量了不同热处理温度下Ba0.9Sr0.1TiO3(BST)薄膜的椭偏光谱。建立适当的拟合模型,并用Cauchy色散模型描述BST薄膜的光学性质,用最优化法获得了所用样品的光学常数（折射率n和消光系数k）谱及禁带能Eg比较这些结果,初步得到了BST薄膜的折射率n、消光系数k和禁带能Eg随退火温度变化的变化规律。     

碲铌铅玻璃的椭圆偏振光谱研究

折射率,色散和吸收系数是用于超高速全光开关的光学材料的重要品质指数。本文用椭圆偏振仪对碲铌铅（TNP）玻璃试样作波长自动扫描测量,测得在波长λ＝258.3-826.6nm范围内的折射率图谱与消光系数图谱,从而可计算各试样的阿贝数ud和非线性折射率n2,结果表明TNP玻璃具有较高的n2,因此TNP玻璃是可以作为超高速全光开关候选材料之一。     

Ba_(0.9)Sr_(0.1)TiO_3薄膜的椭偏光谱研究

用椭偏光谱仪首次在光子能量为２．１～５．２ｅＶ的范围内,测量了不同热处理温度下Ｂａ０．９Ｓｒ０．１ＴｉＯ３（ＢＳＴ）薄膜的椭偏光谱,建立适当的拟合模型,并用Ｃａｕｃｈｙ色散模型描述ＢＳＴ薄膜的光学性质,用最优化法获得了所有样品的光学常数（折射率η和消光系数κ）谱及禁带能Ｅｇ．比较这些结果,初步得到了ＢＳＴ薄膜的折射率η、消光系数κ和禁带能Ｅｇ随退火温度变化的变化规律．     

用消光式椭圆偏振光谱测量薄膜光学参数的方法

本文主要介绍如何应用 TP—77型椭偏仪与 WDF 反射式单色仪组合,实现不同波长下的消光椭偏测量。此方法可测量薄膜厚度、折射率、吸收系数等光学参数。     

ZnO薄膜材料的发光谱

随着人们对ZnO薄膜材料发光特性的不同深入，发现了不同能量位置的多个发光峰，本文对用不同方法制备的ZnO薄膜材料的发光谱、发光特性及其相应的发光机制、国内外研究动态进行了综合评述。介绍了由带间跃迁、激子复合和缺陷能级引起的发光和发光谱特性。     

溅射气压对TbFeCo磁光薄膜的光学常数的影响

利用直流磁控溅射制备了TbFeCo/Si薄膜，采用可变入射角全自动椭圆偏振光谱仪，测量了用磁控溅射法制备的TbFeCo/Si薄膜的光学常数，测量能量范围为1．5～4．5eV。分析了不同氩气压强对磁控溅射制备的TbFeCo/Si磁光薄膜的光学常数的影响。实验结果表明，在低能区域，样品的所有光学常数均随压强增加而增加，受制备工艺影响较大。但在高能区域，光学常数随压强的变化相对说来不再明显．     

光谱拟合法确定一种钙钛矿结构薄膜材料的复数光学常数

为了获得一种钙钛矿结构镧锶锰氧La0.8Sr0.2MnO3薄膜材料的复数光学常数,利用光学薄膜原理和数学优化方法,并基于钙钛矿结构材料的色散模型,对磁控溅射技术制备的不同厚度的镧锶锰氧薄膜在波数400～1250cm-1范围内的反射光谱进行了全谱拟合,并由拟合参数确定了薄膜的复数光学常数.拟合结果显示,测试光谱和拟合光谱较为一致,说明钙钛矿结构材料的色散模型适用于描述La0.8Sr0.2MnO3薄膜的光学特性,利用该色散模型并通过光谱拟合法获得La0.8Sr0.2MnO3薄膜的复数光学常数是获得此材料光学特性的一种有效的方法.     

ITO薄膜的透射谱解谱

用直流磁控溅射法在普通载波片上制备了厚度130hm左右的ITO薄膜,分别在100、200、300和400℃下退火lho测量了退火前后几个样品的XRD和透射率,利用椭偏解谱方法对几个样品的透射谱进行建模及解谱,结果表明,未退火样品'为非晶结构,退火后为多晶结构;退火温度在300℃以下的样品,随着退火温度的升高其n和k值都有明显的降低,退火温度为400℃的样品n和k值却有所增大.利用吸收系数得到了几个样品的直接带隙,其变化范围在3.7eV一3.9eV之间.     

Developing an epitaxial growth process for ZnO by MOCVD using real-time spectroscopic ellipsometry

Real-time diagnostics are an essential tool in the development and improvement of growth processes for new materials. Here we use real-time spectroscopic polarimetric observations of zinc oxide deposition, and a chemical model derived therefrom, to develop a method of growing dense, two-dimensional zinc oxide epitaxially on sapphire by metalorganic chemical vapor deposition. With the transition between deposition and etching being 13% in the diethylzinc flow rate, it is unlikely that we would have discovered this process without the use of real-time spectroscopic ellipsometry. New photoluminescence data support our conclusion that using this cyclical growth process yields improved material.     

Carrier concentration dependent optical properties of wurzite InN epitaxial films on Si(111) studied by spectroscopic ellipsometry

The refractive index and optical absorption of wurzite InN epilayers grown on Si(111) substrates with a β-Si₃N₄/AlN(0001) double-buffer by nitrogen-plasma-assisted molecular-beam epitaxy were studied by employing spectroscopic ellipsometry (SE). The crystalline quality of the InN epilayers were investigated by cross-sectional transmission electron microscopy, X-ray diffraction, and scanning electron microscopy. SE results analyzed by the Adachi's model for the dielectric function show that the optical absorption edge of InN varies in the range of 0.76–0.83 eV depending on the carrier concentration, which in turn can be adjusted by the thickness of the AlN buffer layer.     

Spectroscopic ellipsometry study of thin film thermo-optical properties

Spectroscopic ellipsometry (SE) was employed to realize in-situ monitoring and the determination of thermo-optic coefficients (TOC) of thin films by integrating a temperature controlled hot stage to the ellipsometer and applying the empirical relationship of Cauchy between the refractive index and wavelength in the data analysis. Magnetron sputtered titanium oxide thin films of 350 nm thick both as-deposited and post-deposition annealed were prepared on silicon wafers for this investigation. Results of ellipsometric analysis show that as-deposited TiO₂ films have a negative TOC of ? 1.21 × 10^? 4 K^? 1 at 630 nm over the test temperature range 304–378 K. The post-deposition annealing at 923 K for 2 hours leads an increase in film refractive index to 2.29 from 2.17 for as-deposited TiO₂ films, and an enhancement in TOC up to ? 2.14 × 10^? 4 K^? 1. X-ray diffraction (XRD) and scanning electron microscopy (SEM) cross-sectional analysis were performed for film structure characterization.     

The determination of interface layers by spectroscopic ellipsometry

Spectroscopic ellipsometry has recently proved to be particularly useful for determining the presence and properties of interface layers between a substrate and a dielectric overlayer. The principles and optimum conditions for measuring these layers are given. Examples discussed include Si₃N₄ on silicon, SiO₂ on silicon and GaAs oxide on GaAs.     

Nanoporous structure of a GdF(3) thin film evaluated by variable angle spectroscopic ellipsometry

As excimer lasers extend to deep-ultraviolet and vacuum-ultraviolet wavelengths at 193 and 157 nm, optical coatings experience the challenge of eliminating possible environmental contamination, reducing scattering loss, and increasing laser irradiation durability. Wide bandgap metal fluorides become the materials of choice for the laser optics applications. To understand the optical properties of nanostructure fluoride films, thin GdF(3) films grown on CaF(2) (111) substrates were evaluated by variable angle spectroscopic ellipsometry. An effective medium approximation model was used to determine both the film porosity and the surface roughness. Structural evolution of the GdF(3) film was revealed with improved ellipsometric modeling, suggesting the existence of multilayer structure, a densified bottom layer, middle layers with increasing porosity, and a rough surface. The nanostructure of the film and the surface roughness were confirmed by atomic force microscopy. The attraction of the nanostructure to environmental contamination was experimentally demonstrated.     

Cubic CdS thin films studied by spectroscopic ellipsometry

CdS polycrystalline films were grown onto glass substrates by chemical bath deposition (CBD) and characterized by spectroellipsometry, X-ray diffraction and transmission electron microscopy. The X-ray diffraction patterns of the samples showed the presence of a CdS cubic phase (β-CdS) and of Cd2SiO4 as interfacial material. Using electron diffraction it was possible to index the films as cubic CdS. From effective dielectric function measurements and from reported optical data for the dielectric function of cubic CdS crystals, grown by vapour phase epitaxy, it was possible to fit the experimental data to an effective medium approximation, and to deduce the film thickness, the void fraction and the field screening. This revised version was published online in August 2006 with corrections to the Cover Date.     

Optical study of ion-deposited diamond-like carbon films using spectroscopic ellipsometry

Spectroscopic ellipsometry was used for the characterization of ion-deposited diamond-like carbon (DLC) films, including the determination of film thickness and optical properties of DLC. The measured spectra in the wavelength range from 300 to 850 nm were analyzed with an appropriate fitting model, which was constructed according to the nominal sample structure in which the optical properties of DLC were described by a Cauchy dispersion model. Reasonably good agreement was found between the measured and calculated spectra for all samples studied, indicating that the models used were appropriate and that the calculated results were reliable. The results of our analysis suggest that, under the same deposition conditions (i.e., same substrate temperature and same chamber pressure), the optical properties of ion-deposited DLC film did not change much even if the film was prepared with quite different gas flow ratios.     

In-situ protein adsorption study on biofunctionalized surfaces using spectroscopic ellipsometry

Techniques currently employed to evaluate biomolecular interactions on surfaces require the use of radiolabeled, enzymatic, or fluorescent-tags to record and report the binding event. Ellipsometry has proven to be a powerful tool in understanding the biomolecular interactions on solid substrates and, typically does not require the labeling of the ligand or the receptor. In this present study, the adsorption kinetics of Human Serum Albumin (HSA) on functionalized silicon surfaces were evaluated using in-situ ellipsometry. In-situ ellipsometry was used to estimate the thickness of the adsorbed layers and the adsorption and desorption kinetics of HSA on functionalized surfaces. In this study, dense, self assembled monolayers were fabricated using aminopropyltriethoxysilane (APTES) and mixed silanes using APTES and methyltriethoxysilane at a ratio of 1:10, to serve as a template for protein immobilization on silicon surfaces. The silane derivatized surfaces were further modified using three different ligands/receptors that have been reported to bind HSA, namely: a linear peptide, a polyclonal antibody against human serum albumin, and small synthetic ligand (2, 4, 6-Tris(dimethylaminomethyl)phenol. The amount of HSA adsorbed was observed to increase with time, and with the initial concentration of the HSA solution. The adsorption kinetics of HSA on functionalized surfaces was approximated by a simple model for protein adsorption. A good model fit was obtained for the experimental data, thus enabling the interpretation of the adsorption kinetics of HSA on functionalized silicon surfaces. The effect of different HSA binding ligands on the rate constants affecting protein adsorption and desorption were studied.     

Optical properties and switching of a Rose Bengal derivative: A spectroscopic ellipsometry study

Optical properties in terms of the complex-valued dielectric function were determined for spin-coated films of a Rose Bengal derivative using variable angle of incidence spectroscopic ellipsometry in the visible and infrared wavelength regions. In addition, the thickness and roughness of the films were determined and related to the solution concentration of Rose Bengal. Switching between two different oxidation states of the Rose Bengal derivative was investigated. The two states were chemically induced by exposure to vapors of hydrochloric acid and ammonia, respectively. A substantial and reversible change of the optical properties of the films was observed.