Ellipsometry Method Research Articles

Application of Tamm Plasmon Polaritons and Cavity Modes for Biosensing in the Combined Spectroscopic Ellipsometry and Quartz Crystal Microbalance Method.

Low-cost 1D plasmonic photonic structures supporting Tamm plasmon polaritons and cavity modes were employed for optical signal enhancement, modifying the commercially available quartz crystal microbalance with dissipation (QCM-D) sensor chip in a combinatorial spectroscopic ellipsometry and quartz microbalance method. The Tamm plasmon optical state and cavity mode (CM) for the modified mQCM-D sample obtained sensitivity of ellipsometric parameters to RIU of ΨTPP = 126.78 RIU−1 and ΔTPP = 325 RIU−1, and ΨCM = 264 RIU−1 and ΔCM = 645 RIU−1, respectively. This study shows that Tamm plasmon and cavity modes exhibit about 23 and 49 times better performance of ellipsometric parameters, respectively, for refractive index sensing than standard spectroscopic ellipsometry on a QCM-D sensor chip. It should be noted that for the optical biosensing signal readout, the sensitivity of Tamm plasmon polaritons and cavity modes are comparable with and higher than the standard QCM-D sensor chip. The different origin of Tamm plasmon polaritons (TPP) and cavity mode (CM) provides further advances and can determine whether the surface (TPP) or bulk process (CM) is dominating. The dispersion relation feature of TPP, namely the direct excitation without an additional coupler, allows the possibility to enhance the optical signal on the sensing surface. To the best of our knowledge, this is the first study and application of the TPP and CM in the combinatorial SE-QCM-D method for the enhanced readout of ellipsometric parameters.

Polarimetric spatio-temporal light transport probing

Light emitted from a source into a scene can undergo complex interactions with multiple scene surfaces of different material types before being reflected towards a detector. During this transport, every surface reflection and propagation is encoded in the properties of the photons that ultimately reach the detector, including travel time, direction, intensity, wavelength and polarization. Conventional imaging systems capture intensity by integrating over all other dimensions of the incident light into a single quantity, hiding this rich scene information in these aggregate measurements. Existing methods are capable of untangling these measurements into their spatial and temporal dimensions, fueling geometric scene understanding tasks. However, examining polarimetric material properties jointly with geometric properties is an open challenge that could enable unprecedented capabilities beyond geometric scene understanding, allowing for material-dependent scene understanding and imaging through complex transport, such as macroscopic scattering.In this work, we close this gap, and propose a computational light transport imaging method that captures the spatially- and temporally-resolved complete polarimetric response of a scene, which encodes rich material properties. Our method hinges on a novel 7D tensor theory of light transport. We discover low-rank structure in the polarimetric tensor dimension and propose a data-driven rotating ellipsometry method that learns to exploit redundancy of polarimetric structure. We instantiate our theory with two imaging prototypes: spatio-polarimetric imaging and coaxial temporal-polarimetric imaging. This allows us, for the first time, to decompose scene light transport into temporal, spatial, and complete polarimetric dimensions that unveil scene properties hidden to conventional methods. We validate the applicability of our method on diverse tasks, including shape reconstruction with subsurface scattering, seeing through scattering media, untangling multi-bounce light transport, breaking metamerism with polarization, and spatio-polarimetric decomposition of crystals.

Optical properties of biochemical compositions of microalgae within the spectral range from 300 to 1700 nm.

The optical properties of biochemical compositions of microalgae are vital for the improvement of biosensor design, photobioreactor design, biofuel, and biophotonics techniques. A combination method using both the double optical pathlength transmission method (DOPTM) and the ellipsometry method (EM) is called DOPTM-EM, and it is used to acquire the optical constants of protein, lipid, and carbohydrate of Haematococcus pluvialis, Nannochloropsis sp., and Spirulina in both a solid state and a solution state within the visible and near-infrared spectral range. For different types of microalgae, the refractive indices of protein and carbohydrate in the solid state are similar to each other, but show an observed difference from lipid in the solid state. The refractive indices of protein and carbohydrate in the solution state presents a visible distinction in the researched spectral range. The absorption indices of protein, lipid, and carbohydrate in the solid state for these three types of microalgae are close to each other in the spectral range of 300-500 nm. However, an observed difference is shown in the spectral range of 500-1700 nm. For ease of application, the refractive index of biochemical composition of microalgae was fitted based on the Sellmeier equation. We believe this work can provide a reference to obtain the optical properties of biomaterial with high accuracy.

A study of oxide layer growth on the surface of aluminium alloys with Ti, Zr, Hf during heating in air

The growth of surface oxide films on binary aluminium alloys with transition metal (TM) Ti, Zr and Hf additives at temperatures 600 and 620° С in air was studied using the single-wave ellipsometry method (wavelength 0.6328 µm). It was shown that the annealing temperature affects the growth rate and extinction coefficient of surface oxide films for alloys having ∼5 at.% and ∼18 at.% TM in aluminium. Alloys with hafnium demonstrated the most active growth of oxide films during heating. A considerable increase in the extinction coefficients of oxide films was observed during oxidation of Al ∼18 at.% TM alloys. The optical properties of alloys (substrates) were found to correlate with their chemical composition. The aluminium alloys with 6 and 18.5 at.% Ti retain their resistance to thermal oxidation in air at the indicated temperatures.

Spectroscopic ellipsometry methods for brevetoxin detection

The spectroscopic ellipsometry (SE), and attenuated internal reflection spectroscopic ellipsometry (TIRE) are promising methods in label-free biosensing applications. An ellipsometer running under surface plasmon resonance (SPR) conditions has unique advantages over other SPR-based methods in terms of sensitivity and real-time/label-free measurement capability. In this study, both SE and TIRE-based brevetoxin B (BTX) sensors were developed using two anti-BTX aptamers reported before. A new aptamer sequence was also derived from these two antiBTX aptamers using predictive modeling tools and an exclusion method. All three antiBTX aptamers' analytical performances were quite competitive in terms of both detecting range and detection limits. However, the selectivity of the previously reported aptamers against analogs of BTX was poor at low detection ranges, especially for okadaic acid. Furthermore, the selectivity of the derived aptamer was lower than its predecessors. The sensors were capable of detecting BTX in the range of 0.05 nM–1600 nM in the TIRE and 0.5 nM–2000 nM in the SE configuration. The detection limits of the sensors were 1.48 nM (1.32 ng/mL) and 0.80 nM (0.72 ng/mL) for SE and TIRE configurations, respectively. Both configurations have been used successfully to detect BTX standards spiked into real fish and shrimp samples.

The new innovative optic complete method of identification of oil and its fraction

Development and demonstration of a new method for highly accurate forecasting of the hydrocarbon composition of oil based on determining the spectrum of its universal material constant–dielectric function, as by direct measurement using the method of spectroscopic ellipsometry, are today accepted as the world standard for determining the optical functions of any substance in a liquid or solid state, and by its quantum-mechanical calculation from first principles to complete coincidence with the measurement results. A methodology will be proposed for the complete description of any oil and the identification of it belonging to a particular oilfield. The methodology is not only universal and highly accurate, but also economical. In this work, we obtained several groups of fractions of crude oilsamples from different oil fields in Azerbaijan, which were accessed by spectroscopic ellipsometry over the 1.5–6.5 eV spectral range at room-temperature. Optical constants and dielectric function were obtained for massive samples of each substance and fractions. The proposed method is a complete dielectric fingerprint of oils for widespread use, including for environmental monitoring of oil-contaminated areas of the sea and land.

Activation of film growth on indium phosphide by pulsed photon treatment

Photon activation of various physicochemical processes by the radiation of powerful pulsed xenon lamps (radiation range of 0.2-1.2 µm) is one of the promising areas of material science. The aim of this study was to determine the effect of preoxidative pulsed photon treatment on the process of thermal oxidation of indium phosphide with a nanosized layer of V2O5 on the surface, as well as its effect on the composition and morphology of the formed films. We determined the optimal mode of pre-oxidative pulsed photon treatment of magnetron-formed V2O5/InP heterostructures with a radiation density of 15 J/cm2. By laser and spectral ellipsometry methods, photon activation of V2O5/InP before thermal oxidation was found to increase the thickness of the formed films practically twofold. X-ray diffraction analysis confirms the intensification of the phosphate formation process. The morphological characteristics of the films were determined by atomic force microscopy.Pre-oxidative pulsed photon treatment with an optimal radiation density of 15 J/cm2 activates the thermal oxidation of V2O5/InP heterostructures. It is associated with the formation of new active centres and accelerated rearrangement of chemical bonds in the intermediate complexes of the V2O5 catalyst with semiconductor components

Application of the Spectral Ellipsometry Method to Study the Processes of Atomic Layer Deposition

Application of the Spectral Ellipsometry Method to Study the Processes of Atomic Layer Deposition

Sol-gel Growth of Ni-doped CdS on Glass Substrates: Effect of Spin Coating Speed and Dopant Concentration

Background: In this work, CdS thin films were synthesized by the sol-gel method (spin coating technique) on glass substrates to investigate the optical behavior of the film. Methods: Different substrate spin coating speeds of 2400, 3000, 3600 rpm and different Ni dopant concentrations of 0 wt.%, 2.5 wt.%, and 5 wt.%) were investigated. The optical properties of thin films, such as the refraction index, extinction coefficient, dielectric constant, and optical bandgap energy of the layers were discussed using spectroscopic ellipsometry method in the wavelength range of 300 to 900 nm. Results: It can be deduced that substrate rotation speed and dopant concentration have an influence on the optical properties of thin films by decreasing the rotation speed of the substrate, which results in films with more thicknesses, and more optical interferences were observed in the results. Conclusion: The samples doped with Ni, when compared to pure ones, were found to have more optical bandgap energy.

Optical properties of native (anodic) layer on the InAlAs surface of different morphology

The influence of InAlAs/InP(001) heterostructures surface morphology on the optical properties (dispersive refractive index and extinction coefficient) of the anodic layer, formed by the oxidation in low-energy Townsend gas-discharge O2-Ar-containing plasma at room temperature, was studied using atomic force microscopy and ellipsometry methods. High resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to determine the anodic layer morphology and chemical composition. It is shown that the growth structural defects (pits) on the InAlAs surface, with a density 106–107 cm−2, do not significantly influence the optical properties of the amorphous anodic layers, mainly consisting of In2O3, Al2O3, As2O3 and elemental arsenic quite uniformly distributed over their depth and area. The thickness of thin (≤10 nm) oxide layers on InAlAs is measured at a high accuracy by the nondestructive ellipsometry method using the optical model of a single-layer isotropic film on an absorbing substrate.

Surface structure of Gd20Co80 alloy

Gd 20 Co 80 alloy was studied applying experimental methods of spectral ellipsometry, atomic force and scanning tunneling microscopy. The experimental results exhibit the eutectic two-phase structure of this alloy. Clusters of a phase with a lower content had a lesser concentration of free carriers, which resulted in smaller tunnel currents during the measurements. To analyze the experimental data, a theoretical approach was developed, which was based both on the quantum-mechanical methods of configurational interaction and on three-diagonal Toeplitz matrices formalism. This approach allowed us to describe in detail the energy bands formation process in solid clusters with a relatively small quantity of atoms, which as a consequence enabled to describe the Shockley surface states as well as the existence of a surface layer with partially formed energy bands. Spectral-ellipsometric measurements of Gd 20 Co 80 alloy thin films confirmed a significant difference between the measured optical constants for 20-nm thick films and larger films. Quantum-mechanical molecular calculus allowed to obtain optical constants for several supercells of Gd-Co chemical compounds and confirmed the acquired experimental and theoretical results.

Investigation of volume fraction of GaP nanowires by SEM characterization and spectroscopic ellipsometry

In this paper we focus on investigation of GaP volume fraction in GaP nanowires (NWs) prepared on GaP substrates by MOVPE using VLS mode. For this purpose, spectroscopic ellipsometry (SE) and scanning electron microscopy (SEM) image processing methods were used showing a good agreement. In ellipsometry, composition of GaP and void was modeled using linear gradient model in combination with Bruggeman Effective Medium Approximation (BEMA). From this model the volume fraction of GaP on the top of the nanowires was determined from 1.5%–6.3%) and in the bottom of the nanowires from 34.8%–39.6%), respectively. The histogram of GaP nanowires SEM image was divided into 10 bins above the plane. The volume fraction of GaP nanowires determined from these bins ranged from 1.4 % to 3.8 % on the top of the nanowires and from 33.5%–46.2% in their bottom. Linearity of the SEM histogram bins gradient was further compared to the linearity of the linear gradient layer model.

Quantitative analysis of stereoscopic molecular orientations in thermally reactive and heterogeneous noncrystalline thin films via variable-temperature infrared pMAIRS and GI-XRD

The quantitative estimation of stereoscopic molecular orientations in semicrystalline polymer thin films with characteristic heterogeneous structures is essential for the development of advanced film materials. Grazing-incidence X-ray diffraction (GI-XRD) is a powerful technique used to evaluate the orientational order of crystalline lattices; however, it provides the orientational order of only ordered regions (crystal and glassy liquid crystal regions). In contrast, infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) can provide the averaged orientational order of overall regions in a film regardless of sample crystallinity. This paper combines variable-temperature (VT) pMAIRS, static GI-XRD and spectroscopic ellipsometry and reports general insight into the molecular orientation mechanism occurring in polymer films revealed through the precise analysis of the structural evolution of linear poly(amic n-alkyl ester), PAE, with different lengths of n-alkyl chains during thermal curing, which involves solvent evaporation and dehydration imidization reactions to form the corresponding polyimide (PI). This combined method clarified that the PAE and PI thin films had a heterogeneous structure consisting of a glassy liquid-crystalline (ordered) region and a nonoriented amorphous region. Furthermore, imidization proceeded faster in the amorphous region than in the ordered (oriented) region. In addition, anomalies of refractive index and birefringence were found by comparing pMAIRS and spectroscopic ellipsometry, although the effect of the side chain length on the molecular orientation of PI was insignificant. The anomalies indicate that an isotropic void structures were generated by the elimination reaction of the side chains and that the volume fraction of voids increased with increasing side chain length. These results demonstrated that the combination of VT-pMAIRS and GI-XRD is a very powerful tool for the in situ structural analyses of noncrystalline (disordered crystal, glassy liquid crystal, and oriented amorphous) thin-film materials ongoing chemical reactions in their components and is inherently applicable to all kinds of interesting polymeric thin-film materials. Thin film aromatic polyimides were quantitatively analyzed by grazing-incidence X-ray diffraction (GI-XRD), variable-temperature infrared p-polarized multiple-angle resolution spectroscopy (VT-pMAIRS), and spectroscopic ellipsometry (SE) methods. Combining VT-pMAIRS and GI-XRD revealed characteristic heterogeneous structures comprising non-oriented amorphous and oriented liquid-crystalline glass regions. Additionally, SE indicated that the film involved anisotropic-shaped void inducing form-birefringence. Such an excess of birefringence can make it difficult to estimate orientational order using birefringence measurement. This methodology presented here will remarkably contribute to general structural analyses of all intriguing thin-film polymers with characteristic heterogeneity.

Copper Nitride Nanowire Arrays-Comparison of Synthetic Approaches.

Copper nitride nanowire arrays were synthesized by an ammonolysis reaction of copper oxide precursors grown on copper surfaces in an ammonia solution. The starting Cu films were deposited on a silicon substrate using two different methods: thermal evaporation (30 nm thickness) and electroplating (2 μm thickness). The grown CuO or CuO/Cu(OH)2 architectures were studied in regard to morphology and size, using electron microscopy methods (SEM, TEM). The final shape and composition of the structures were mostly affected by the concentration of the ammonia solution and time of the immersion. Needle-shaped 2–3 μm long nanostructures were formed from the electrodeposited copper films placed in a 0.033 M NH3 solution for 48 h, whereas for the copper films obtained by physical vapor deposition (PVD), well-aligned nano-needles were obtained after 3 h. The phase composition of the films was studied by X-ray diffraction (XRD) and selected area electron diffraction (SAED) analysis, indicating a presence of CuO and Cu(OH)2, as well as Cu residues. Therefore, in order to obtain a pure oxide film, the samples were thermally treated at 120–180 °C, after which the morphology of the structures remained unchanged. In the final stage of this study, Cu3N nanostructures were obtained by an ammonolysis reaction at 310 °C and studied by SEM, TEM, XRD, and spectroscopic methods. The fabricated PVD-derived coatings were also analyzed using a spectroscopic ellipsometry method, in order to calculate dielectric function, band gap and film thickness.

Design and Simulation of Graphene/2D Interlayer Surface Plasmon Resonance Biosensor Based on Ellipsometry Method

Design and Simulation of Graphene/2D Interlayer Surface Plasmon Resonance Biosensor Based on Ellipsometry Method

Terahertz Bessel Beam Applied to Thickness Measurement of Ellipsometry Methods

Terahertz Bessel Beam Applied to Thickness Measurement of Ellipsometry Methods

Strong Coupling between Tamm and Surface Plasmons for Advanced Optical Bio-Sensing

The total internal reflection ellipsometry method was used to analyse the angular spectra of the hybrid Tamm and surface plasmon modes and to compare their results with those obtained using the conventional single SPR method. As such type of measurement is quite common in commercial SPR devices, more detailed attention was paid to the analysis of the p-polarization reflection intensity dependence. The conducted study showed that the presence of strong coupling in the hybrid plasmonic modes increases the sensitivity of the plasmonic-based sensors due to the reduced losses in the metal layer. The experimental results and analysis of the optical responses of three different plasmonic-based samples indicated that the optimized Tamm plasmons ΔRp(TP) and optimized surface plasmons ΔRp(SP) samples produce a response that is about five and six times greater than the conventional surface plasmon resonance ΔRp(SPR) in angular spectra. The sensitivity of the refractive index unit of the spectroscopic measurements for the optimized Tamm plasmon samples was 1.5 times higher than for conventional SPR, while for wavelength scanning, the SPR overcame the optimized TP by 1.5 times.

Optical method for determination of fatigue damage in organic glass

The features of nucleation, start, and propagation of a crack inside a transparent organic sample are investigated. The distribution of the refractive index and density around the crack was studied by changing of speckle images and ellipsometry method. It was found that the maximum value of the relative change in density is near the crack. This value before the crack start is greater than 0.003. It is proved that the speckle method we offer can be the basis for the creation of various techniques. Using these techniques will allow us to estimate the time before the crack start by the rate of change of physical quantities in small areas of the order of 50 μm and their limiting values. The results of experimental investigations are presented.

Thin‐Metal‐Film‐Based Transparent Conductors: Material Preparation, Optical Design, and Device Applications

AbstractTransparent conductors are essential elements in an array of optoelectronic devices. The most commonly used transparent conductor – indium tin oxide (ITO) suffers from issues including poor mechanical flexibility, rising cost, and the need for annealing to achieve high conductivity. Consequently, there has been intensive research effort in developing ITO‐free transparent conductors over the recent years. This article gives a comprehensive review on the development of an important ITO‐free transparent conductor, that is based on thin metal films. It starts with the background knowledge of material selection for thin‐metal‐film‐based transparent conductors and then surveys various techniques to fabricate high‐quality thin metal films. Then, it introduces the spectroscopic ellipsometry method for characterizing thin metal films with high accuracy, and discusses the optical design procedure for optimizing transmittance through thin‐metal‐film‐based conductors. The review also summarizes diverse applications of thin‐metal‐film‐based transparent conductors, ranging from solar cells and organic light emitting diodes, to optical spectrum filters, low‐emissivity windows, and transparent electromagnetic interference coatings.

Visible-to-near-infrared optical properties of protein, lipid and carbohydrate in both solid and solution state at room temperature

An accurate knowledge of optical constant of protein, lipid and carbohydrate is important for analyzing radiative transport between cells. However, it is difficult to measure precisely the optical constant of these elements due to the complicated sample-making and the limitation of traditional measurement method. In this work, the double optical pathlength transmission method and the ellipsometry method (DOPTM-EM) were used to obtain the optical constants of protein, lipid and carbohydrate of Chlorella sp. (both solid-state and solution-state), solution-state egg protein and solution-state sucrose in the spectral range 300-1700 nm. Isolations of protein, lipid and carbohydrate from Chlorella sp. were conducted. For different types and states of protein, lipid and carbohydrate, the optical constants of these samples are different from each other. The refractive indices of protein and carbohydrate have obvious relationship with the existing state. A significant difference of absorption indices can be observed between the solution-state protein of Chlorella sp. and the egg protein. It is indicated that the amino acids composition of solution-state protein of Chlorella sp. differs from the egg protein. The absorption indices of solution-state carbohydrate do not agree with the solution-state sucrose. For the sake of applications, the fitted formula of the refractive index as a function of wavelength is presented.