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A purge-free controlled living polymerization method, activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP), is used to amplify the occurrence of protein binding events. Detection of ovalbumin is demonstrated where binding of femtomole protein is differentiable from the background using ellipsometry. Moreover, binding of subpicomole protein leads to visually distinguishable spots on the sensor surface within 15 min, which signifies its potential in future development of point-of-need devices. 10.1021/ac900959v

The reflection of s-and p-polarized electromagnetic plane waves from an anisotropic ultrathin dielectric film on transparent isotropic substrate is investigated in the long-wavelength limit. The analytical approximate formulas are obtained for the reflection coefficients and ellipsometric angles that agree with the exact computer solution of the reflection problem for anisotropic systems. The possibilities of using the obtained expressions for resolving the inverse problem for ultrathin anisotropic dielectric films upon isotropic dielectric substrates are discussed. It is shown that a promising technique for determining the optical constants of anisotropic dielectric films on transparent substrates is the integration of ellipsometry and differential reflectivity. OCIS codes: 260.2110, 240.0310, 310.6860, 260.2130, 120.4530.

A rigorous, much simplified, and accurate analysis of the modal field characteristics such as propagation constants, mode power confinement, delay and dispersion characteristics of a single-mode graded-index elliptical core fiber is presented applying a variational method and super-Gaussian approximation of the fundamental modal field. Normalized propagation constants, a fundamental parameter to evaluate other modal characteristics, obtained through this method showed a greater accuracy over the entire range of practical interest in comparison with other reported methods. The effects of various aspect ratios on these characteristics are analyzed. In addition, the effect of Kerr nonlinearity on these characteristics is investigated using the reported method, and a comparison is made with the linear results. OCIS codes: 060.2310, 060.2270, 060.2400.

Ellipsometry is an optical technique that is widely used for determining optical and geometrical properties of optical thin films. These properties are in general extracted from the ellipsometric measurement by solving an inverse problem. Classical methods like the Levenberg--Marquardt algorithm are generally too long, depending on direct calculation and are very sensitive to local minima. In this way, the neural network has proved to be an efficient tool for solving these kinds of problems in a very short time. Indeed, it is rapid and less sensitive to local minima than the classical inversion method. We suggest a complete neural ellipsometric characterization method for determining the index dispersion law and the thickness of a simple Si[O.sub.2] or photoresist thin layer on Si, Si[O.sub.2], and BK7 substrates. The influence of the training couples on the artificial neural network performance is also discussed. OCIS codes: 120.2130, 200.4260.

The two independent components of the gyration tensor of quartz, [g.sub.11] and [g.sub.33], have been spectroscopically measured using a transmission two-modulator generalized ellipsometer. The method is used to determine the optical activity in crystals in directions other than the optic axis, where the linear birefringence is much larger than the optical activity. OCIS codes: 260.1180, 260.1440, 160.1585, 240.2130.

Silicon nanotips fabricated by electron cyclotron resonance plasma etching of silicon wafers are studied by spectroscopic ellipsometry. The structure of the nanotips is composed of columns 100-140 nm wide and spaced by about 200 nm. Ellipsometry data covering a wide spectral range from the midinfrared to the visible are described by modeling the nanotip layer as a graded uniaxial film using the Bruggeman effective medium approximation. The ellipsometry data in the infrared range reveal two absorption bands at 754 and 955 cm-1, which cannot be resolved with transmittance measurements. These bands indicate that the etching process is accompanied with formation of carbonaceous SiC and CHn species that largely modify the composition of the original crystalline silicon material affecting the optical response of the nanotips. OCIS codes: 120.2130, 160.1245, 260.2065, 310.3840.

A three-intensity measurement technique has been employed in polarizer-sample-analyzer imaging ellipsometry to measure the two-dimensional ellipsometric parameters of a coated cylindrical lens. Since azimuth deviation a of a polarizer can also be measured with this three-intensity measurement technique, we tilted a well-calibrated thin-film wafer to identify the orientation of the measured a with respect to the incident plane. Using the analytic property of this measurement technique, we can correct the deviation and determine the thickness profile of the thin film coated on a cylindrical lens. OCIS codes: 120.2130, 310.6870.

The French Laser Megajoule (LMJ) is designed and constructed by the French Commissariat a l'Energie Atomique (CEA). Its amplifying section needs highly reflective multilayer mirrors for the flash lamps. To monitor and improve the coating process, the reflectors have to be characterized to high accuracy. The described spectrophotometer is designed to measure normal specular reflectance with high repeatability by using a small spot size of 100 [micro]m. Results are compared with ellipsometric measurements. The instrument can also perform spatial characterization to detect coating nonuniformity. OCIS codes: 120.1840, 120.3930, 120.3940, 120.5700.

The competitive adsorption at the air-water interface of hen egg-white lysozyme with non-ionic surfactant is studied using tensiometry, ellipsometry and surface dilation rheology. The adsorption is found to depend on the surfactant concentration in the bulk solution and also on the ionic or non-ionic nature of the surfactant.

The spreading characteristics of novel alkanolamine-terminated perfluoropolyether (PFPE) films on carbon surfaces were investigated experimentally by using a scanning micro-ellipsometer. The apparent diffusion coefficients of the novel lubricants were studied in order to evaluate the spreading speed and they were compared with the conventional Z-dol, Z-tetraol, and A20H lubricants. It was found that the mobility of a lubricant is lower when the number of OH end groups is higher. It was also found that the mobility of the alkanolamine-terminated PFPE films was lower than that of conventional lubricants with the same number of OH end groups as that of the alkanolamine-terminated lubricants and that the mobility tendency of the lubricants has a good correlation with their viscosity tendency. In addition, the mobility of ZDPA with a dipropylamine end group (no OH end group) has peculiar characteristics. Its mobility is higher than that of Z-dol when the film thickness of the lubricant exceeds that of one monolayer. However, it is lower than that of Z-dol when the film thickness of the lubricant is less than that of one monolayer. This may be due to the unique interaction between the ZDPA amine group and the carbon overcoat. Index Terms--Alkanolamine-terminated perfluoropolyether films, hard disk drives, head-disk interface, scanning micro-ellipsometry, spreading characteristics.

A hybrid antireflective coating combining homogeneous layers and linear gradient refractive index layers has been deposited using different techniques. The samples were analyzed optically based on spectrophotometric and spectroscopic ellipsometry measurements under different angles of incidence in order to precisely characterize the coatings. The Lorentz-Lorenz model has been used to calculate the refractive index of material mixtures in gradient and constant index layers of the coating. The obtained refractive index profiles have been compared with the targeted ones to detect errors in processes of deposition. OCIS codes: 310.1210, 310.3840.

Chemically cleaned GaP(001) surfaces in aqueous HF solutions are analyzed by using spectroscopic ellipsometry (SE), ex situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), wettability, and photoluminescence (PL) measurements. The wettability measurements have shown that the HF-cleaned surface is hydrophobic and the PL intensity has increased after etching in aqueous HF solutions.

Through numerical simulations, we point out that introduction of an ellipsometric measurement technique to an absorption-based surface-plasmon resonance (SPR) sensor enhances precision and sensitivity in measuring the imaginary part k of the complex refractive index of the sample. By measuring a pair of ellipsometric [DELTA]-[PSI] parameters, instead of the conventional energy reflectance [R.sub.p] of p-polarized light in the Kretschmann optical arrangement, we can detect a small change of k that is proportional to that of the concentration of the sample, especially when k [much less than] 1. While one has difficulty in determining the value of k uniquely by the standard technique, when the thickness of Au under the prism is thin (20-30 nm), the ellipsometric technique (ET) overcomes the problem. Furthermore, the value of k and the thickness [d.sub.s] of the absorptive sample that is adsorbed on Au can be determined precisely. The ET based on the common-path polarization interferometer is robust against external disturbance such as mechanical vibration and intensity fluctuation of a light source. Although only the p-polarized light is responsible for the SPR phenomenon, we show that the introduction of the ET is significant for quantitative analysis. OCIS codes: 120.2130, 240.6680, 120.2130.

The transmission ellipsometric function (TEF) of a film-substrate system relates the polarization change, upon transmission, of an electromagnetic wave obliquely incident on, and transmitted through, a filmsubstrate system. The behavior of the TEF depends on the category of the film-substrate system: negative, zero, or positive. The category is determined by the sign of [N.sub.1] - \[[square root of][N.sub.0][N.sub.2]: negative for a negative film-substrate system, zero for a zero system, and positive for a positive system. We discuss the behavior of the TEFs of the two transparent nonnegative film-substrate systems, zero and positive. We describe the TEF as two successive transformations and analyze its behavior as the angle of incidence and film thickness of the film-substrate system are changed. We use the constant-angle-of-incidence contours and constant-thickness contours to analyze and utilize that behavior. From the analysis and understanding of the behavior of the TEF, and from the definition of a polarization device as a film-substrate system that introduces prescribed polarization changes, we discuss the design of all possible types of polarization devices using either of the two systems. We present a design formula for each. We also present a general formula that is used for the design of any of the devices. Thin-film coatings are treated as polarization devices for the purposes of our discussion. We conclude with a brief discussion of suggested practical modifications to, and simplifications of, ellipsometric memory, which is an interesting application of polarization devices for which there is a patent pending. OCIS codes: 310.1620, 230.1150, 120.2130, 000.3870.

A new microscope is described that is capable of measuring the polarization characteristics of materials in normal-incidence reflection with a demonstrated lateral resolution of 4 [micro]m. The instrument measures eight parameters of the sample Mueller matrix, which can be related to the diattenuation, retardation, circular diattenuation, direction of the principal axis, and the polarization factor. With proper calibration, the eight elements of the sample Mueller matrix can be determined to better than 0.001-0.002 for small values. Examples are given for aluminum, futile (Ti[O.sub.2]), and calcite (CaC[O.sub.3]). OCIS codes: 120.2130, 120.5700, 180.0180, 230.5440.

Fast and efficient metrology tools are required in microelectronics for control of ever-decreasing feature sizes. Optical techniques such as spectroscopic ellipsometry (SE) and normal incidence reflectometry are widely used for this task. In this work we investigate the potential of spectral Mueller polarimetry in conical diffraction for the characterization of 1D gratings, with particular emphasis on small critical dimensions (CDs). Mueller matrix spectra were taken in the visible (450-700 am) wavelength range on a photoresist grating on a Si substrate with 70/240 nm CD/period nominal values, set at nine different azimuthal angles. These spectra were fitted with a rigorous coupled-wave analysis (RCWA) algorithm by using different models for the grating profile (rectangular and trapezoidal, with or without rounded corners). A detailed study of the stability and consistency of the optimal CD values, together with the variation of the merit function (the mean square deviation [D.sup.2]) around these values, clearly showed that for a given wavelength range, this technique can decouple some critical parameters (e.g., top and bottom CDs, left and right sidewall projections) much more efficiently than the usual SE. OCIS codes: 050.1950, 120.2130, 120.3940.

Specular ellipsometry is a well-known and efficient technique to characterize surfaces and coatings. This technique has been extended to the measurement of scattered light. We present an experimental setup, using a polarization modulator, which permits us to characterize transition layers and roughness without a calibration procedure. Experimental results are presented concerning transition layers for damage threshold applications and for rough surfaces or bulks. OCIS codes: 120.0120, 120.5820, 240.0240, 240.5770.

The optical properties of magnetron-sputtered aluminum and AA1050 aluminum alloy sheet are examined qualitatively using total reflectance and quantitatively by means of visible spectroscopic ellipsometry. Significant changes in reflectance and optical constants are observed that are related to the incorporation of oxide in the aluminum bulk.

The external reflection geometry and a three-phase system are commonly used by infrared spectroscopic ellipsometry (IRSE) of organic self-assembled monolayers (SAMs). A report is presented, which shows how IRSE measurements involving organic SAMs are affected by the thickness and surface roughness of the substrate Au layer.

The dielectric function of poly 2-methoxy-5-hexyloxy phenylenevinylene and the alternating copolymers with N-hexylphenothiazine grown on glass is measured using angle spectroscopic ellipsometry and Raman spectroscopy at room temperature. The dielectric function of each polymer is estimated, the band gap parameters determined, and the shift of band gap parameters and phonon wave numbers in terms of the chemical structure is discussed in this article.

Poly(ethylene oxide) (PEO)-brushes are generally recognized as protein-repellent surfaces, and although a role in discouraging microbial adhesion has been established for some strains and species, no study exists on the effects of PEO-brushes on a large variety of bacterial and yeast strains. In this paper, a PEO-brush has been covalently attached to glass and silica by reaction in a polymer melt. Subsequently, the presence of a PEO-brush was demonstrated using contact angle measurements, X-ray photoelectron spectroscopy and ellipsometry. For five bacterial (Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus salivarius, Escherichia coli and Pseudomonas aeruginosa) and two yeast strains (Candida albicans and Candida tropicalis), adhesion to PEO-brushes was compared with adhesion to bare glass in a parallel plate flow chamber. The initial deposition rates of Sta. epidermidis, Sta. aureus and Str. salivarius to glass were relatively high, between 2400 and 2600 [cm.sup.-2][S.sup.-1], while E. coli and P. aeruginosa deposited much more slowly. The initial deposition rates of the yeasts to glass were 144 and 444 [cm.sup.-2][s.sup.-1] for C. albicans GB 1/2 and C. tropicalis GB 9/9, respectively. Coating of the glass surface with a PEO-brush yielded more than 98% reduction in bacterial adhesion, although for the more hydrophobic P. aeruginosa a smaller reduction was observed. For both yeast species adhesion suppression was less effective than for the bacteria and here too the more hydrophobic C. tropicalis showed less reduction than the more hydrophilic C. albicans. The PEO-brush had a thickness of 22 nm in water, as inferred from ellipsometry. Assuming that on bare glass the adhered micro-organisms are positioned only a few nanometers away from the surface and that the brush keeps them at a distance of 22 nm, it is calculated that the brush yields a sevenfold attenuation of the Lifshitz-Van der Waals attraction to the surface between the micro-organisms and the surface. Decreased Lifshitz-van der Waals attraction may be responsible for the suppression of the microbial adhesion observed.

Spectroscopic ellipsometry (SE) was used to get structural information in P(super +) ion-implanted silicon layers. No change in the structure of silicon surface after ion implementation was found.

A new spectroscopic ellipsometry method is presented for liquid crystal (LC) display twist angle and retardation measurement. By varying the polarizer and analyzer angles only, a transmission spectrum containing null transmission at some particular wavelengths can be obtained.

Self-assembled monolayer films of a metallotetraazaphthalocyanine are prepared using two different reaction conditions. A different number of bonds connecting the chromophore with the coupling molecule are suggested as an explanation to differences in the absorption bands for the two films.

The feasibility of using the pyro-optic analog of pyroelectric devices in infrared imaging is investigated via the analysis of temperature dependence of the refractive indices of several pyro-optical materials. The wavelength of the maximum temperature dependence of antimony sulfur iodide, molybdenum disulphide and bismuth vanadium tetraoxide semiconductors were obtained via spectroscopic ellipsometry. Results were then related to the reflectance coefficients and refractive indices of these materials. Temperature variations between 0.001 and 0.01 degrees centigrade can be detected via thermal imaging as long as the reflectance coefficient is monitored.

The article explains the different stages that are observed in the interactions taking place between the deuterium atoms and the amorphous hydrogenated carbon films. Isotope exchange, soft-layer formation and steady-state erosion are shown to be some of the main steps involved in the process.

The Mueller matrix ellipsometry technique is employed for the characterization and for explaining the optical properties of the inclined GaSb nanopillars.

In situ real-time spectroscopic ellipsometry measurements are performed during vacuum deposition in order to examine molecular orientation in organic amorphous films. The molecular orientation is controlled by the substrate temperature in multilayer structures, which is prepared by using only one material, where each layer has different optical and electrical properties.

Ellipsometry is used for examining the structural evolution of intrinsic and doped hydrogenated amorphous silicon (a-Si:H) thin films during their exposure to a hydrogen plasma in conditions of chemical transport. The behavior of the p-type material is attributed to the effects of boron which has reduced the etching rate by hindering the formation of volatile species such as Si[H.sub.4] and has promoted quick and repeated nucleation of nanoparticles and crystallites that contribute to the growth film.

An experimental procedure for accurate measurement of anchoring energy strength of liquid crystal cells is described. The results indicated that the technique could be an optimum candidate for the measurement and industrial implementation of applications such as vertical aligned nematic cells, chosen for its widespread use in the present display market.

Maxwell's equations were applied to study the optical properties of monolayer graphene deposited on a dielectric substrate material. The study results provide insight into optical quantities such as reflected polarization and reflection coefficient which are significant for obtaining information about the conductivity tensor of the graphene layer.

The thickness, refractive index, density and interface properties of thin thermal oxides on both Si- and C-terminated 4H-SiC faces are examined by ellipsometry using optical models of increasing complexity. The studies have shown a decrease in mass density with decreasing oxide thickness by using a combination of ellipsometry and backscattering spectrometry, which is explained by the surface roughness, depending on the layer thickness disclosed by atomic force microscopy.

The remote plasma deposition of hydrogenated amorphous carbon (a-C:H) thin films is examined by using in situ spectroscopic ellipsometry (SE). The studies have shown that the B-spline parametrization has served as a stepping stone to physics-based models like the Tauc-Lorentz oscillator.

Magnetron sputtered Hf[O.sub.2] layers formed on a heated Si substrate are analyzed by spectroscopic ellipsometer (SE) and x-ray photoelectron spectroscopy (XPS) depth profiling techniques. The studies have shown that the highly reactive sputtered Hf atoms have consumed some of the oxygen atoms from the underlying Si[O.sub.2] to form Hf[O.sub.2], leaving Si-Si bonds beh ind.

The hydrogenation mechanism of Pd thin films is studied in real time by measuring the variation in ellipsometric [PSI] and [DELTA] by using is situ spectroscopic ellipsometry. The studies have shown that after the whole Pd metal layer changed to the mixture layer, the concentration of hydride in the mixture layer increased and when the concentration reached on, the hydrogenation of Pd is finished.

Thermal annealing behaviors of GaAs(001) surfaces in dry [N.sub.2] atmosphere are analyzed by using spectroscopic ellipsometry and photoluminescence (PL) techniques. The native GaAs oxide has acted as a passivation film against annealing-induced PL degradation for temperatures below 400 [degree]C.

Optical properties of white tin ([beta]-Sn) are examined by using spectroscopic ellipsometry in the photon-energy range between 0.6 and 6.5 eV at room temperature. Dielectric-related optical constants, such as the complex refractive index, absorption coefficient and normal-incidence reflectivity, of bulk [beta]-Sn films are described.

The preparation of porous silicon layers by electrochemical etching of p-type single-crystal Si (c-Si) of varying dopant concentration that result in gradually changing morphology and nanocrystal (wall) sizes in the range of 2-25 nm is described. The combined EMA+MDF multilayer method provides a more detailed description of the material and layer structure using a composition of voids and c-Si with nanocrystalline Si reference compared to simple effective medium approximation (EMA).

Fourier transform variable angle infrared spectroscopic ellipsometry (IRSE) is used for examining a group of silicon wafers that are implanted with high doses and annealed in high temperature. The ionization probability is analyzed as a function of impurity concentration in the optical model in order to describe the carrier concentration profile, by which the impurity concentration and carrier concentration profiles are determined simultaneously.

Photoluminescence measurements and spectroscopic ellipsometry are used for examining the optical properties of silicon nanocrystals (Si-ncs) prepared by silicon implantation into silicon oxide. The Si-nc dielectric function is calculated for different Si-nc systems by using a single Tauc-Lorentz (TL) oscillator in the Bruggemann effective medium approximation (BEMA).

X-ray photoemission spectroscopy and spectroscopy ellipsometry (SE) are employed to study composition-dependent electronic structure and optical properties of [Hf.sub.1-x][Si.sub.x][O.sub.y] gate dielectrics on Si at 450 degree Celsius. The results suggested that the [Hf.sub.1-x][Si.sub.x][O.sub.y] film offer sufficient tunneling barriers for electrons and holes to apply them as potential candidates as alternative gate dielectrics.

An in situ real time ellipsometric studies of the reoxygenation kinetics of reduced LaNi[O.sub.3]-[delta]] (LNO) films at different temperatures and different oxygen pressures are presented. The observations showed that ellipsometry is a powerful and noninvasive tool to study in situ the insulator/metal transition that allows the tuning of the oxygen stochiometry [delta] by controlling in real time the optical indexes associated with the LaNi[O.sub.3-[delta]] oxidation degree.

Spectroscopic ellipsometry is used for studying the electro-optic effect in lead zirconate titanate (PZT) thin films grown epitaxially on Nb-doped SrTi[O.sub.3](001) substrates by RF magnetron sputtering. The presence of the linear electro-optic effect in unpoled PZT films is attributed to the existence of a built-in polarization and simultaneous poling during measurements.

A high current pulsed cathodic arc deposition system equipped with multiple cathodes is used for the deposition of titanium and carbon (Ti/C) as well as titanium carbide and carbon (TiC/C) multilayers. Electron energy loss spectroscopy has shown that the carbon layer has undergone a transition from [sp.sup.2] rich to [sp.sup.3] rich material and the ellipsometry results have shown that the optical properties of the carbon have changed as a function of thickness.

Ex situ spectroscopic ellipsometry (SE) from the near infrared (IR) to near ultraviolet (UV) range is used to examine the layered structure of boron-doped polycrystalline diamond thin films grown by chemical vapor deposition (MWCVD) with varying boron to carbon concentration in gas phase. A simplified three-layer structural model can be used for simulating the ellipsometry spectra satisfactorily.

Ellipsometry was used to study the wetting of water by hexadecane as a function of the concentration of the cationic surfactant dodecyltrimethylammonium bromide (DTAB) in the aqueous phase and temperature. The results data support the interpretation of the L-S phase transition as the wetting of a liquid-like mixed monolayer of surfactant + alkane by a surface frozen layer of hexadecane.

The variable angle spectroscopic ellipsometry in the photon energy range 0.54-4.13 eV was used to study the optical properties of as-prepared (amporphous) and thermally crystallized (fcc) flash evaporated [Ge.sub.2][Sb.sub.2][Te.sub.5] thin films. The optical properties of as-prepared and fcc flash evaporated [Ge.sub.2][Sb.sub.2][Te.sub.5] thin films are found to be very similar to those values reported for sputtered thin films.

The adsorption of the cell-binding protein fibronectin on flat and nanometer scale rough tantalum oxide surfaces is examined by using ellipsometry and quartz crystal microbalance with dissipation (QCM-D). The studies have shown that the nanorough tantalum oxide surfaces have promoted additional protein conformational changes, an effect especially apparent from the QCM-D signals, which is interpreted as an additional stiffening of the formed fibronectin layers.