Generating porosity in metal oxides thin films through introduction of polymer micelles

The generation of porosity in Nb₂O₅ sol–gel films through introduction of polymer micelles of commercially available copolymer Pluronic PE6800 [poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)] was studied using direct observation of film morphology by Transmission Electron Microscopy and indirect calculations of free volume fraction by optical means. Mesoporous Nb₂O₅ films were deposited by the sol–gel and spin-coating methods and templated with aqueous solutions of Pluronic PE6800 with concentrations below and above critical micelle concentration determined by the modified dye solubilization method. The influence of the duration of the postdeposition annealing on total pore volumes was investigated by reflectance measurements and consequent calculation of optical properties and free volume fraction by Bruggeman effective medium theory. The possible application of the films in optical sensing of vapors has been demonstrated through reflectance measurements prior to and after acetone vapors exposure.     

Role of surface defects and microstructure in infrared optical properties of thermochromic VO2 materials

Thermochromic vanadium dioxide VO₂ exhibits a semi-conducting to metallic phase transition at T_c=68 °C, involving strong variations in optical transmittance, reflectance and emissivity. However, the optical contrasts observed in thin films or nanostructured compacted samples seem to depend on both surface microstructure and surface crystal texture. In the case of opaque materials, surface defects might play a drastic role in optical reflectivity. As the high temperature metallic phase of VO₂ is opaque for infrared radiations, we used aluminum samples as standards allowing us to correlate reflectivity responses with porosity and surface defects. Then, various polycrystalline and nanostructured VO₂ samples compacted at various pressures and presenting variable surface roughness were prepared. Thin films were deposited by radio frequency sputtering process. The samples were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Optical properties (reflectance and emissivity) were analyzed above and below the transition temperature, making use of specific FTIR equipments. In thin films, the deposited VO₂ phase was systematically oriented and surface porosity was very weak. In polycrystalline samples, as the compaction pressure increased, surface porosity decreased, and infrared optical contrast increased. In such samples, preferred orientations were favored for low applied pressures. These features clearly show that the main parameters conditioning the optical contrast should be the surface defects and porosity, not the preferred crystal orientations. As an additional interesting result, the surfaces formed from compacted nanocrystalline VO₂ powders present improved optical contrast for reflectance and emissivity properties.     

多功能抗激光损伤高反射膜

为了能同时满足半导体激光器和YAG激光器对薄膜的特殊要求,在分析高反射膜理论的基础上,选取TiO2和SiO2为高、低折射率材料镀制了周期性多层介质高反射膜。研究了材料的光学及机械特性,重点解决了薄膜的消偏振和抗激光损伤问题。实验采用电子束真空镀膜并加以考夫曼离子源辅助沉积,利用TFC软件进行膜系设计,通过调整镀膜工艺参数和监控方法,在10mm×1．8mm的K9基底上镀制了符合要求的高反射膜,结果表明,当激光以45°入射时,薄膜在900～1100nm的P光与s光的反射率均大于99．95％。所制备的高反射膜性能稳定,抗激光损伤阈值高,能同时满足两种激光器的使用要求。     

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.     

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80nm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80～160nm之间．     

离子束溅射沉积Ir膜真空紫外反射特性研究

根据吸收材料基底上单层金属膜数学计算模型,对不同基片上各种厚度的Ir膜真空紫外反射率进行了优化计算.采用离子束溅射沉积技术,在石英、K9玻璃和Si基片上沉积了不同厚度的Ir膜,研究了基片、表面厚度、离子束能量及镀后热处理对Ir膜反射率的影响,在波长120 nm处获得了近30％正入射反射率.     

Optical anisotropy and surface morphology of InGaAs lattice-mismatched with GaAs(0 0 1)

We investigated surface morphology and optical anisotropy of strained InGaAs films grown on GaAs(0 0 1) substrate using atomic force microscopy (AFM) and reflectance difference/reflectance anisotropy spectroscopy (RDS/RAS). High temperature (HT)-grown samples were found to have a rippled surface structure, however for films grown using a low temperature (LT) growth technique, the surface morphology was significantly improved, without the ripple structure seen on the HT samples. Furthermore, ex situ RD spectra of LT-grown samples showed notable peaks near the critical energies of band structure originated from bulk electronic transitions.     

Effect of Alumina and Chromium Interlayers on Microstructures and Optical Properties of Thin Ag Films on Glass Substrates

Effects of alumina and chromium interlayers on the microstructure and optical properties of thin Ag films are investigated by using spectrophotometry, x-ray diffraction and AFM. The characteristics of Ag films in Ag/glass, Ag/l2O3/glass and Ag/Cr/glass stacks are analysed. The results indicate that the insertion of an Al2O3 or Cr layer decreases the grains and influences the reflectance of Ag films. The reflectance of the Ag film can be increased by controlling the thickness of alumina interlayer. The stability of Ag films is improved and the adhesion of Ag films on glass substrates is enhanced by alumina as an interlayer.     

立方氮化硼薄膜的光学带隙

用射频溅射法在p型Si(100)衬底上沉积立方氮化硼(c-BN)薄膜,薄膜的成分由傅里叶变换红外谱标识,用紫外-可见分光光度计测量了c-BN薄膜的反射光谱,利用K-K(Kramers-Kroning)关系从反射谱计算出c-BN薄膜的光吸收系数,进而确定c-BN薄膜的光学带隙.对于立方相含量为55.4%的c-BN薄膜,光学带隙为5.38eV. 关键词： 立方氮化硼薄膜 光学带隙 K-K关系     

苹果盛果期冠层高光谱与其组分特征的定量模型研究

从分析苹果树盛果期冠层高光谱入手,结合同一时间的数码照片,在Erdas,ViewSpec Pro,DPS和LIBSVM等软件的支持下,采用相关分析、线性回归、逐步回归、基于BP人工神经网络分析、支持向量机回归方法,探析高光谱反射率及其转换数据与冠层组分指数间的关系。结果表明,冠层反射率受地表反光膜的影响显著;原始反射率与果叶比的相关性最好,611~680 nm为反映两者关系的特征波段;在特征波段内,依据原始反射率和果叶比所建立的4种模型都可满足预测需要,但基于BP人工神经网络模型和支持向量机回归模型整体上优于一元线性回归模型和多元线性回归模型,尤以支持向量机回归模型精度最高。研究结果可为后续的苹果遥感估产工作提供理论支持。     

记录薄膜Te—In—Sb光学性质的研究

采用高频溅射方法制成Te-In-Sb系统的非晶态薄膜.系统的研究了不同组分薄膜的透射、反射谱,及其在结晶过程中的变化.用透射电镜研究了Te-In-Sb薄膜的结构和晶化过程.分析了组分对薄膜的吸收系数、介电常数、光学能隙等光学性质的影响.并由此综合评价了Te-In—Sb系统中比较适合作为光盘介质的组成.     

Electronic transport and carrier concentration in conductive ZnO:Ga thin films

Transparent and conductive Ga-doped ZnO (ZnO:Ga) films were post-annealed after sputter deposition, and their structural and electrical properties were investigated. Post-annealing led to an improvement of crystallinity along the [001] direction, but did not change lateral grain size. Therefore, carrier concentration and electron mobility of films were analyzed as a function of crystallinity. The electrical parameters were obtained with both optical reflectance based on the Drude free-electron model and the Hall method, and similar tendencies were observed within the two methods. Even though the lowest resistivity was demonstrated by the film annealed at 550 °C, the optimum values for carrier concentration and mobility were observed in films with different post-annealing temperatures.     

Preparation of polybutylene terephthalate/silica nanocomposites by melt compounding: Evaluation of surface properties

Influence of nanosilica on surface properties of poly(butylene terephthalate) was investigated by the use of Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurement (CAM), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). FTIR results indicated that surface groups of silica have some interfacial interactions and bonding with carboxyl or hydroxyl end groups of PBT chains. AFM and SEM figures of the resultant nanocomposites illustrated increased surface roughness compared to pure PBT. Optical properties of nanocomposite films were finally determined by the aid of reflectance spectrophotometer.     

Substrate temperature dependence of the properties of scandium-doped ZnO films deposited by sputtering

Structural and optical properties of Sc-doped ZnO films grown by RF magnetron sputtering at different substrate temperatures were investigated. All the ZnO:Sc films are polycrystalline with the hexagonal wurtzite structure. X-ray diffraction patterns of the films showed that the doped-films have (0 0 2) as preferred orientation when the deposition temperature was increased from 250 °C to 300 °C. All the films are in a state of compressive stress, whereas the stress decreases gradually with increasing substrate temperature. The average transmittance of these films was above 90% in the wavelength range from 400 nm to 800 nm. The optical band gap of these films was determined. The optical constants of these films were determined using transmittance and reflectance spectra.     

矫顽力可调的多孔硅基Fe膜

采用电化学腐蚀法制备了不同多孔度的多孔硅(PS),再通过磁控溅射法在该PS衬底上沉积了一定厚度的Fe膜;并对样品进行了X射线衍射的结构分析、扫描隧道显微技术的表面形貌观察和磁光克尔效应的测量.发现在同一Fe膜厚度下，相对于参考样品硅上的Fe膜，多孔硅上Fe膜的矫顽力更大;同时观察到多孔硅基Fe膜随着PS多孔度的增加，矫顽力相应变大;而对于多孔度相同的多孔硅基样品,随着Fe膜厚度的增加矫顽力却逐步减小.得出了多孔硅特有的海绵状疏松结构能有效调节Fe膜矫顽力大小的结论. 关键词： 多孔硅 海绵状结构 Fe薄膜 矫顽力     

Oblique angle deposition of TiO2 thin films prepared by electron-beam evaporation

Optical, structural and photocatalytic properties of TiO₂ thin films obliquely deposited on quartz glass substrate using an electron-beam evaporation method were investigated. The photocatalytic activity of the films was evaluated by photodecomposition of methylene blue. An increase in incident deposition angle increased the porosity and surface roughness of the TiO₂ films. As a result, the photocatalytic activity was enhanced with incident deposition angle up to 60°. However, a further increase in incident deposition angle to 75° reduced the photocatalytic activity due to a lack of the crystalline phase.     

椭偏光谱法研究溶胶-凝胶TiO2薄膜的光学常数

以钛酸丁酯为前驱体,采用溶胶-凝胶工艺成功制备了TiO₂薄膜.利用反射式椭圆偏振光谱仪测量了薄膜的椭偏参量Ψ和Δ,并用Cauchy模型对椭偏参数进行数据拟合,得到了薄膜的厚度和光学常数在380—800 nm的色散关系.用分光光度计测量了薄膜的反射率,并用干涉法计算薄膜的厚度;使用原子力显微镜观测了薄膜的表面微结构,分析讨论了不同退火温度处理的薄膜微结构与光学常数之间的关系.研究结果表明,Cauchy模型能较好地符合溶胶-凝胶TiO₂薄 关键词： 光学常数 2薄膜')" href="#">TiO₂薄膜 溶胶-凝胶 椭圆偏振     

Cu膜的光学特性尺寸效应及最小连续膜厚研究

采用离子束溅射在K9玻璃基底上沉积了不同厚度的Cu膜,利用Lambda-900分光光度计,测量了波长为310 nm到1300 nm范围内Cu膜的反射率和透射率.选定波长为310、350、400、430、550、632、800、1200 nm时对薄膜的反射率、透射率和吸收率随膜厚变化的关系进行研究.同时,对Cu膜的光学常量也进行了讨论.结果显示,Cu膜的光学特性都有明显的尺寸效应.将波长为550 nm时的反射率和透射率随Cu膜厚度变化关系的交点对应厚度作为特征厚度, 该厚度可认为是金属Cu膜生长从不连续膜进入连续膜的最小连续膜厚.根据这一特征判据,离子束溅射沉积Cu膜样品的最小连续膜厚为33 nm.利用原子力显微镜观测了膜厚在特征厚度附近时Cu膜的表面形貌.     

Properties of amorphous carbon nitride prepared by RF reactive sputtering

The local microstructure and optical and electrical properties were investigated of amorphous carbon nitride (a-CN) films deposited by reactive radio-frequency (RF) sputtering. Two series prepared in nitrogen or in a nitrogen and argon mixture were studied. The optical properties were investigated by transmittance/reflectance and photothermal deflection spectroscopies. Combined infrared measurements and Raman scattering spectroscopies were used to investigate the microstructure of a-CN films in terms of nitrogen incorporation within the films and C sp ² content. These experiments were completed by dark electrical conductivity measurements performed in coplanar configuration in the temperature range 50–450?K. The films exhibit semiconductor behaviour and the temperature dependence suggests two types of conduction. An increase in nitrogen incorporation induces an increase with clustering of sp ² phase replacing C=C olefinic groups with aromatic groups.     

Optical properties of selenium sulfide thin film produced via chemical dropping method

This paper describes the production of selenium sulfide (SeS₂) crystalline thin film on commercial glass substrates, via chemical bath deposition. Transmittance, absorption, dielectric constant and refractive index of the produced films were investigated by UV/VIS Spectrum. It was found that changes occurred on the characteristics of the films and they were determined as a function of selenium sulfide concentration, which varied between 2?×?10^?3 and 5?×?10^?3 M. The structure of the film was analyzed using FTIR spectrum. The calculated refractive index values fell between 1.5 and 1.6, whereas the transmission ratio of the films was around 80–90%. Moreover, a peak in the reflectance was observed at 320–330 nm for all investigated samples. The highest dielectric constant for the films was obtained at the deposition concentration of 0.005 M. This study is believed to be useful for thin film production.