Polarized angular dependence of three-dimensional light-scattering for nanoparticles on thin film wafer

Bidirectional ellipsometry has been developed as a technique for distinguishing among various scattering features near surfaces. The polarized angular dependence of three-dimensional light-scattering by the nanoparticles on thin film wafer is calculated and measured. These calculations and measurements yield angular dependence of bidirectional ellipsometric parameters for out-of-plane light-scattering. The experimental data show good agreement with theoretical predictions for different nanoparticle diameters and thin film thicknesses when bidirectional ellipsometry was employed to measure nanoparticles (60 nm, 100 nm, and 200 nm) on Si wafers with different film thicknesses of 2 nm, 5 nm, and 10 nm. Not only are the diameters of the nanoparticles determined, but also the film thicknesses can be calculated and distinguished from the measurement results. Additionally, the results indicate that improved accuracy is possible for measurements of scattering features from nanoparticles and thin films.     

Polarized angular dependence of out-of-plane light-scattering measurements for nanoparticles on wafer

Bidirectional ellipsometry has been developed as a technique for distinguishing among various scattering features near surfaces. The polarized angular dependence of out-of-plane light-scattering by the nanoparticles on wafer is calculated and measured according to Rayleigh limit. These calculations and measurements yield angular dependence of bidirectional ellipsometric parameters for out-of-plane scattering. The experimental data show good agreement with theoretical predictions for different diameter of nanoparticles. The results suggest that improvements for accuracy are possible to perform measurements of scattering features from nanoparticles. The angular dependence and the polarization of light scattered by nanoparticles can be used to determine the size of nanoparticulate contaminants on silicon wafers.     

Characteristics of coherent transverse optical phonon in CuI thin films on Au nano-films

We have investigated the coherent phonon in CuI thin films deposited on Au films with nanoscale roughness. It is found that the coherent transverse optical (TO) phonon in the CuI thin film on the Au film is dramatically enhanced, whereas that in the CuI thin film without the Au film is hardly observed. The enhancement of the coherent TO phonon in the CuI thin film on the Au film will originate from the surface enhanced electric field around the surface of the Au film with nanoscale roughness. To clarify the properties of the enhanced coherent phonon, we have investigated the pump-power dependence and pump-polarization dependence of the coherent phonon. We discuss the generation process of the coherent phonon in the CuI thin film on the Au film as compared with the pump-power dependence and the pump-polarization dependence.     

Surface measurement using active vision and light scattering

This paper reviews the recent progress in surface measurement methods using active vision and light-scattering techniques. The active vision methods with different structured light patterns and the corresponding techniques are summarized. The surface roughness and defects inspection with light-scattering are discussed. After the review, an integrative method to measure surface waviness and form, roughness is proposed.     

Determination of surface roughness from light scattering measurements

We have measured the angular dependence of the p- and s-pollarized light scattered on films, which are supported by fine polished Suprasil substrates. To study the roughness of the surface we have varied the evaporation process and the thickness of the silver film. We quantitatively determine the roughness structure by using a non scalar scattering theory. The roughness structure is found in good agreement with measurements on the same films using ATR-techniques.     

Light scattering by complex ice-analogue crystals

Angle-dependent light-scattering measurements on single ice analogues crystals are described. Phase functions and degree of linear polarization are measured for electrodynamically levitated crystals. A procedure for randomizing particle orientation during levitation is demonstrated. The dependence of scattering on the shape, complexity and surface roughness of the crystals is examined. The phase functions from complex crystals with smooth surfaces show little dependence on shape. There is close agreement between the measured functions and the analytic phase function for ice clouds. However, rosettes with rough surfaces have qualitatively different phase functions, with raised side and back scattering. The asymmetry parameter is typically about 0.8±0.04 and 0.63±0.05 for smooth and rough crystals, respectively. The 22° halo peak is present for smooth rosettes and aggregates but absent for rough rosettes. Two-dimensional scattering patterns from several crystals in fixed orientations are also shown. The results suggest that it may be possible to use such patterns to discriminate not only between crystals of different shape but also to obtain some information on surface properties.     

Roughness of pigment coatings and its influence on gloss

A robust method is used for analyzing roughness at a wide range of lateral length scales. The method is based on two-point correlation where both the amplitude and lateral spacing of surface heights are considered when determining the roughness. Atomic force microcopy and confocal optical microscopy images were captured for a set of pigment-coated samples. The effects of sampling interval, image size and filtering on surface roughness were studied. Isotropy and periodicity of roughness were determined by analyzing the angular distribution of the correlation length (T) and the autocorrelation function (ACF). A clear dependence of root mean square (RMS) roughness (σ) on T was established for randomly distributed surfaces. By taking into account the σ-T dependence it was possible to obtain σ for various length scales for each sample and thus attaining the most relevant σ for a certain surface function, which in this study was specular reflection of light (gloss). The roughness analysis showed that a small amount of DPP coating was sufficient to completely cover and change the surface of the substrate, while kaolin coatings gave a different response.     

Photochemical and photothermal dissociation of PETN during laser initiation

The temperature dependence of the efficiency of laser initiation (λ = 1060 nm) of pure PETN with an open and closed surface and PETN with a light-scattering additive (0.5% MgO) and an open surface was studied. It was found that the closing of the surface and introduction of light-scattering additives leads to a change in the temperature dependence of the initiation threshold. The observed effect is associated with the specificity of the photoinduced fragmentation of PETN molecules in defective areas of the crystal lattice.     

Optical spectra and angular dependence of the visible light emitted by metal-insulator-metal tunnel junctions

Optical spectra and angular dependence of electromagnetic emission from Al-Al oxide-Ag and Al-Al oxide-Au tunnel junctions are reported. Data from Ag junctions are consistent with the assumption of roughness induced decoupling of surface polaritons, while data from Au junctions suggest that the emission results from direct coupling of current fluctuations in the junction to the external radiation fields.     

Out-of-plane coercive field of Ni80Fe20 antidot arrays

The out-of-plane magnetic anisotropy and out-of-plane magnetization reversal process of nanoscale Ni₈₀Fe₂₀ antidot arrays deposited by magnetron sputtering technique on an anodic aluminum oxide (AAO) membrane are investigated. The angular dependence of out-of-plane remanent magnetization of Ni₈₀Fe₂₀ antidot arrays shows that the maximum remanence is in-plane and the squareness of the out-of-plane hysteresis loop follow a |cos θ| dependence. The angular dependence of out-of-plane coercivity of Ni₈₀Fe₂₀ antidot arrays shows that the maximum coercivity lies on the surface of a cone with its symmetric axis normal to the sample plane, which indicates a transition of magnetic reversal from curling to coherent rotation when changing the angle between the applied magnetic field and the sample plane.     

Anisotropy of auger processes in monocrystalline graphite

The angular dependence of the KVV Auger spectrum fine structure in the graphite monocrystal has been found. It cannot be explained by the influence of surface defects and roughness; therefore it has been determined in terms of the local electron density anisotropy in graphite.     

微纳复合结构表面稳定润湿状态及转型过程的热力学分析

自然界中的微纳复合结构超疏水表面由于其独特的润湿性质引起了人们的广泛关注, 大量实验研究表明了仿生人工微纳复合结构表面润湿性能的优越性, 然而液滴在微纳复合结构表面的润湿状态和转型过程的理论研究还并不完善. 本文首先用热力学方法分析了液滴在微纳复合结构表面可能存在的所有状态(四种稳定润湿状态和五种亚稳态到稳定态转型中的过渡态), 推导出了相应的能量表达式及表观接触角方程; 基于最小能量原理, 确定液滴在微纳复合结构表面的稳定状态, 较以往模型相比, 能够更好的预测已有的实验结果; 其次研究了微纳结构尺寸对稳定润湿状态和亚稳态到稳定态转型过程的影响; 最后提出了微纳复合结构表面设计原则, 即确定“超疏水稳定区”尺寸范围, 为超疏水表面的制备提供理论依据.     

Tribological properties of silicate materials on nano and microscale

We studied the friction properties of four model silicate materials at the nanoscale and microscale. From nanotribology, we characterized the tribological properties at single asperity contact scale and from microtribology, we characterized the tribological properties at multi asperity contact scale. First, for each material we measured chemical composition by XPS, Young's modulus by acoustical microscopy and roughness σ by atomic force microscopy (AFM). Second, we measured the nanofriction coefficients with an AFM and the microfriction coefficients with a ball probe tribometer, for three hardnesses of the ball probe. We identified one friction mechanism at the nanoscale (sliding friction) and two friction mechanisms at the microscale (sliding friction and yielding friction). Comparison of the nano and microfriction coefficients at the same sliding friction regime shown, that the tribological properties of these materials didn’t depend on roughness.     

Diffraction efficiency and light-scattering power of photothermoplastic holographic gratings

The diffraction efficiency and light-scattering power of holographic gratings formed on the surface of a two-layer photothermoplastic carrier with a pit structure of deformation are studied. The influence of the height and regularity of the pit deformation on the diffraction efficiency and light-scattering power is studied. It is shown that the pronounced resonance character of the dependence of the diffraction efficiency on the spatial frequency in the case of pit deformation is related to the distribution of the deformation depth over spatial frequencies; however, the dominant factor is the mutual arrangement of pits within the interference fringe. It is found that the light-scattering power is determined for the most part by the size and density of the deformation. A new method is proposed for determining the resolution of photothermoplastic carriers with pit deformation, which apparently can be used for photothermoplastic carriers with any irregular structure of deformation. This method is based on the analysis of the dependence of the light-scattering power of holographic gratings on their spatial frequency. It is shown that the resolution depends inversely proportionally on the thickness of the thermoplastic layer of the optical carrier.     

Suppression of electro-osmotic flow by surface roughness

We show that nanoscale surface roughness, which commonly occurs on microfabricated metal electrodes, can significantly suppress electro-osmotic flows when excess surface conductivity is appreciable. We demonstrate the physical mechanism for electro-osmotic flow suppression due to surface curvature, compute the effects of varying surface conductivity and roughness amplitudes on the slip velocities of a model system, and identify scalings for flow suppression in different regimes of surface conduction. We suggest that roughness may be one factor that contributes to large discrepancies observed between classical electrokinetic theory and modern microfluidic experiments.     

Bidirectional surface wave splitter at visible frequencies

We experimentally demonstrate a metal-film bidirectional surface wave splitter for guiding light at two visible wavelengths in opposite directions. Two nanoscale gratings were patterned on opposite sides of a subwavelength slit. The metallic surface grating structures were tailored geometrically to have different plasmonic bandgaps, enabling each grating to guide light of one wavelength and prohibit propagation at the other wavelength. The locations of the bandgaps were experimentally confirmed by interferometric measurements. Based on these design principles, a green-red bidirectional surface wave splitter is demonstrated, and the observed optical properties are shown to agree with theoretical predictions.     

Consistency of the Surface Roughness Determined from Soft-X-Ray Reflectance and Surface Profiles Measured Using a Scanning Tunnelling Microscope: Coherence Length of the Soft X-Rays

There exists serious inconsistency between the rms surface roughness determined from the Debye-Waller factor for the soft-x-ray reflectance analysis and that measured with an optical surface profiler. We have measured the surface profile of evaporated films using a scanning tunnelling microscope, and reproduce the profile with the Fourier components whose spatial wavelength is shorter than the coherence length of the incident soft x-rays in the reflectance measurement. The rms surface roughness derived from the high-pass filtered profile agrees well with that determined using the reflectance measurement. This result explains straightforwardly the photon-energy dependence of the surface roughness estimated by the soft-x-ray reflectance method.     

Evaluation of nanoscale roughness measurements on a plasma treated SU-8 polymer surface by atomic force microscopy

A comparison between roughness data obtained with an atomic force microscope (AFM) on different surfaces requires reliable roughness parameters. In order to specify the appropriate parameters for nanoscale roughness measurements, we compared the root mean square (rms) roughness and the relative surface area (sdr) as function of varying scan size, speed and pixel size. By using oxygen plasma (24 kJ) treated SU-8 with an average rms roughness of 2.6 ± 0.5 nm as reference surface, the repeatability of the method was evaluated for dynamic (tapping) and contact mode. The evaluation of AFM images indicated a decrease of the effective tip radius after a few measurements. This degradation of the tip lowers the resolution of the image and can affect roughness measurements.     

测量金属膜粗糙度的表面等离子激元光谱方法

介绍了确定金属膜表面粗糙度的表面等离子激元光谱方法。测量了二种银膜在表面等离子激元激发条件下的光散射强度分布。通过与理论计算的拟合，得到了描写这二种银膜／空气同粗糙界面的特征参数。     

非接触铜铝纳米薄膜侧向移动相互作用的分析

采用分子动力学方法模拟铜铝纳米薄膜相对侧向移动的相互作用能。研究了铜薄膜的侧向位移从0Å到50Å时温度、相互作用间距、表面形貌和表面粗糙度对作用能的影响。结果表明,相互作用强度随温度的增加而增大,随相互作用间距的减小而增大,随表面粗糙度的增大而减小。为研究薄膜在纳米尺度的相互作用提供了一个新的方法。