Mueller matrix ellipsometry (MME) provides the 4×4 Mueller matrix of a sample under test, which determines how the state of polarization is changed as light interacts with the sample. Due to the ...redundant information contained in the Mueller matrix, MME has gained more and more extensive applications in the characterization of surfaces, interfaces, thin films, and nanostructures. In addition, the instrumentation of MME has also achieved great developments since its advent in the 1970s. In this paper, we will first review the basic principle as well as the common system layouts of MME for the full Mueller matrix measurement. Then, the basic procedure of ellipsometry data analysis is reviewed. After that, some new developments in MME in our lab for different applications are introduced, including the broadband MME, the high-resolution imaging MME, and the high-speed MME. Some emerging applications of the developed MMEs are also presented. Conclusions and perspectives of the advanced ellipsometry are finally drawn and discussed.
•Development of user-friendly, durable, light-weight, and cost-effective 3D-printed SPR module integrated with commercial Ellipsometer.•Label-free, highly surface sensitive, non-invasive, and ...real-time integrated optical sensing platform.•Bulk refractive index sensitivities for wavelength and phase interrogation were achieved as 3098±177 nm/RIU and 5839±229 °/RIU, respectively.•Layer-by-layer interaction between oppositely charged poly-electrolytes (PDDA and PSS).•Achieving a detection limit of 3 pM for Anti-BSA by studying BSA/Anti-BSA interaction.
The present work focuses on advancing optical sensing abilities through the instrumentation of Surface Plasmon Resonance Spectroscopy (SPR) with a commercial ellipsometer. This approach involves the incorporation of an in-house-built 3D-printed SPR module to circumvent the complexity of optical alignments with the ellipsometer. Currently, no commercially available SPR-enhanced Ellipsometry (SPRE) system exists, and previous systems are mostly custom-designed. Our work addresses this gap by introducing an in-house-built SPR module compatible with Ellipsometry and constructed using 3D printing technology. The 3D-printed SPR module is user-friendly, durable, lightweight, and cost-effective, incorporating a flow cell crucial for liquid media operation. This integrated tool provides a highly surface-sensitive, non-invasive, and label-free optical sensing platform. The developed SPR-Ellipsometry platform demonstrates excellent performance in detecting biochemical analytes and multilayer adsorption of poly-electrolytes. The bulk refractive index sensitivity measurement was performed to calibrate the Au sensor chip. The Wavelength (SPR mode), amplitude (Ψ), and phase interrogation (∆) exhibit bulk refractive index sensitivities of 3098 ± 177 nm/RIU, 835 ± 22 °/RIU and 5839 ± 229 °/RIU, respectively. We obtained the refractive index resolution around 1.712 × 10−7 RIU. Protein-protein (BSA/Anti-BSA) interactions were also conducted, achieving a detection limit of 3 pM for Anti-BSA. This work will significantly expand the functionality of SPRE sensors by offering enhanced sensitivity, rich information, and high precision, as well as opening avenues for more efficient and accessible optical sensing technologies. Moreover, the study establishes a foundational framework for researchers, shedding light on the potential of 3D printers in laboratories and expediting the development of cost-effective integrated sensing platforms.
Display omitted
Conventional spectroscopic ellipsometry is a powerful tool in optical metrology. However, when it comes to the characterization of non-periodic nanostructures or structured fields that are much ...smaller than the illumination spot size, it is not well suited as it integrates the results over the whole illuminated area. Instead, imaging ellipsometry can be applied. Especially imaging Mueller matrix ellipsometry is highly useful in nanostructure characterization and defect inspection, as it is capable to measure the complete Mueller matrix for each pixel in a microscope image of the sample. It has been shown that these so-called Mueller matrix images can help to distinguish geometrical features of nanostructures in the sub-wavelength regime due to visible differences in off-diagonal matrix elements. To further investigate the sensitivity of imaging Mueller matrix ellipsometry for sub-wavelength sized features, we designed and fabricated a sample containing geometrical nanostructures with lateral dimensions ranging from 50 to 5,000 nm. The structures consist of square and circular shapes with varying sizes and corner rounding. For the characterization of their Mueller matrix images, we constructed an in-house Mueller matrix microscope capable of measuring the full Mueller matrix for each pixel of a CCD camera, using an imaging system and a dual-rotating compensator configuration for the ellipsometric system. The samples are illuminated at 455 nm wavelength and the measurements can be performed in both transmission and reflection. Using this setup, we systematically examine the sensitivity of Mueller matrix images to small features of the designed nanostructures. Within this contribution, the results are compared with traceable atomic force microscopy measurements and the suitability of this measurement technique in optical nanometrology is discussed. AFM measurements confirm that the fabricated samples closely match their design and are suitable for nanometrological test measurements. Mueller matrix images of the structures show close resemblance to numerical simulations and significant influence of sub-wavelength features to off-diagonal matrix elements.
Ellipsometrie ist eine der vielseitigsten Methoden zur optischen Nanostrukturcharakterisierung. Insbesondere die Müller-Matrix-Ellipsometrie ermöglicht die Messung von optischen oder geometrischen ...Parametern mit Genauigkeiten bis in den Sub-Nanometer-Bereich. In der konventionellen Ellipsometrie wird dabei über die komplette Beleuchtungspunktgröße gemittelt. Wenn der strukturierte Bereich auf der Probe kleiner ist als der Beleuchtungspunkt, oder die Struktur keine Periodizität aufweist, kann das Messergebnis durch in den Randbereichen reflektiertes Licht beeinträchtigt werden. Besonders problematisch ist dies bei freistehenden Nanostrukturen mit charakteristischen Größen kleiner als die Beleuchtungspunktgröße. In solchen Fällen kann abbildende Ellipsometrie genutzt werden. Dabei wird eine Müller-Matrix für jedes Pixel in einem Kamerabild gemessen, wodurch der Polarisationseinfluss der Probe lokal bestimmt wird. In diesem Beitrag liefern wir Ansätze, konkrete Zusammenhänge zwischen geometrischen Eigenschaften von Nanostrukturen auf Nebendiagonalelemente der Müller-Matrix zu ermitteln. Dazu haben wir einen Aufbau für die Messung von Müller-Matrix-Bildern bei verschiedenen Einfallswinkeln in Transmission und Reflexion realisiert sowie eine Probe gefertigt, mit der wir geometrische Struktureigenschaften in Müller-Matrix-Bildern systematisch messen. Wir stellen Messungen sowie numerische Simulationen zum Vergleich der Ergebnisse vor. Des Weiteren diskutieren wir thermische Einflüsse auf Messergebnisse und stellen einen Algorithmus zu deren Behandlung vor.
•Single phase rock-salt Pb1-xCdxTe (0 ≤ x ≤ 0.15) films were produced.•The lattice constant of Pb1-xCdxTe decreases as a function of Cd concentration.•The band gap of Pb1-xCdxTe blue shifts as the Cd ...concentration increases.•The index of refraction decreased by ∼10 % as Cd increases.
Using spectroscopic ellipsometry, we studied the optical properties of four Pb1-xCdxTe (0 ≤ x ≤ 0.20) films. The Pb1-xCdxTe films, deposited on silicon substrates using an electron-beam deposition technique, show a rock-salt structure, with their lattice constants decreasing as a function of Cd concentration. Ellipsometry measurements, which covered a wide spectral range between 0.1 eV to 4.1 eV, determined the index of refraction and the extinction coefficient of the films. As the Cd concentration increases from 0 % to 20 % in the Pb1-xCdxTe films, the index of refraction decreases by ∼10 %, across the entire energy range. Similarly, there seems to be a decrease in the extinction coefficient with the increase of Cd concentration. An oscillator model, depicting the optical functions of each Pb1-xCdxTe film, allowed us to obtain the band gap of each film which blue-shifts as the Cd concentration is increased. Besides the fundamental band gap, we recovered the higher-order electronic transitions that occur in the Brillouin zone of the Pb1-xCdxTe lattice.
FeSe is regarded as a strong correlation system of simple structure and remarkable tunability in the superconducting transition temperature (Tc). Particularly, the substitution of Se with its ...isoelectronic Te leads to a dome-shaped Tc evolution, positioning the FeSe1-xTex as an ideal platform for exploring the mechanism of iron-based superconductivity. In this study, we employed high-throughput combinatorial molecular beam epitaxy (CLMBE) to fabricate high-quality FeSe1-xTex film with horizontal gradient. The dielectric spectra of FeSe1-xTex were obtained by ellipsometry spectroscopy (SE). We utilized the standard critical point model and first-principles calculation to identify that the observed interband transitions are predominantly sourced from Fe-3d near the Fermi surface. The pseudogap, extracted from the transitions, shows a bowl-like trend as increased Te, which is negatively correlated with Tc, suggesting a qualitative way to predict Tc in the normal-state. The composition-dependent charge dynamics response, derived from Drude oscillators in SE, indicates that electron-electron interactions might play a more substantial role in FeSe1-xTex superconductivity, combined with the unidirectional electron-phonon coupling result in Raman. The variation of plasma frequency and photoinduced carrier dispersion under composition modulation demonstrates the effect of Te in enhancing system interactions, providing valuable support for the design of superconducting optoelectronic devices.
•High-quality FeSe1-xTex film with laterally spread composition was prepared.•Filling the gap of dielectric functions of FeSe1-xTex in 234–1000 nm.•Analyzing the transitions in d-orbitals and pseudogap through Se/Te substitution.•The Drude dielectric contribution indicates the strong electron-electron interaction.•The photoinduced carrier reflects the effect of Te in enhancing system interactions.
40 nm thick La2/3Sr1/3MnO3 (LSMO) thin films were epitaxially grown by Pulsed Laser Deposition (PLD) onto niobium doped SrTiO3 (Nb:STO) substrates, with different Nb concentration from 0.01%wt to ...0.5%wt. The optical characterization of the heterostructures by spectroscopic ellipsometry enables us to extract the optical constants of the manganite heteroepitaxial layer at room temperature. Performing spectrophotometry in the same wavelength range brings a useful cross-validation of the extracted results. In addition, the thickness evaluation of the LSMO layer by spectro-ellipsometry is further validated by both High Resolution X-ray diffraction and X-ray reflectivity, as well as a Transmission Electron Microscopy cross section, taken as a physical reference. This study validates quantitatively the spectro-ellipsometry as a suitable routine tool to measure accurately both thickness and complex refractive index of the LSMO thin film, picturing their peculiar electrical behaviour between both metallic and insulating phases. The relative error on the thickness measurement between X-ray and ellipsometry is less than 5%. The LSMO complex refractive index enabled also a simultaneous estimation of further material properties, such as the optical gap ωg or the mass density ρm, determined with less than 1.5% relative error compared to X-ray reflectivity results.
Display omitted
•Physically-based accurate ellipsometric modelling of heteroepitaxial manganite.•Simultaneous estimation of LSMO thickness, roughness, mass density and optical gap.•Quantitative matching between X-ray and optical techniques on thin film.
Display omitted
•Binding kinetics between immobilized receptor and several genetically engineered ligands (GELs) was evaluated.•GELs were differing by molecular mass and/or by the number of binding ...sites available for the binding of receptor.•GCSF-Receptor, which binds glycoprotein granulocyte colony stimulating factor (GCSF), was immobilized.•Mathematical modelling was applied for the description of interaction between GCSF-Receptor with GCSF-based ligands.•Binding of GCSF-Receptor with GCSF-homodimer ((GCSF)2) was characterized by multi-stage kinetics.
In this research we have evaluated the binding kinetics between an immobilized receptor and several genetically engineered ligands, differing by molecular mass or by the number of binding sites available for the binding to the receptor. Genetically engineered protein (GCSF-Receptor), which contains some antibody parts (Fc domain) and at some extent is similar to antibody because also has two binding sites that selectively bind another protein – glycoprotein granulocyte colony stimulating factor (GCSF), which was immobilized on a thin gold layer in order to design an immunosensor sensitive to GCSF. Three structurally different GCSF-based proteins were genetically-engineered and evaluated as ligands, which selectively bind to immobilized GCSF-Receptor: (i) GCSF monomer (mGCSF), (ii) GCSF-homodimer consisting of two via polypeptide Lα-based linker ‘fused’ GCSF molecules ((GCSF)2Lα) and (iii) GCSF-heterodimer (SCF-Lα-GCSF), which is based on a native GCSF molecule ‘fused’ via Lα-based linker with another protein – a soluble part of stem cell factor (SCF). SCF, unlike GCSF, does not contain any site suitable for GCSF-Receptor binding. The ligands differ by: (i) molecular mass – (GCSF)2Lα and SCF-Lα-GCSF F are two times heavier than mGCS, (ii) number of binding sites – mGCSF and SCF-Lα-GCSF have one binding site, while (GCSF)2Lα has two. The binding kinetics of mGCSF, (GCSF)2Lα, and SCF-Lα-GCSF with immobilized GCSF-Receptor was investigated using total internal reflection ellipsometry. The interaction kinetics of the mGCSF and SCF-Lα-GCSF are both well described using a standard Langmuir kinetics model. However, receptor-ligand association and dissociation rates in the case of SCF-Lα-GCSF ligand are about 10 times lower than that of mGCSF. The association rate of (GCSF)2Lα is about half of that of the mGCSF, which can be explained by the smaller diffusion coefficient of the larger molecule. Moreover, unlike SCF-Lα-GCSF, the (GCSF)2Lα adsorption kinetics cannot be adequately described by the standard Langmuir kinetics model and surface regeneration (induced by ‘washing’) experiments illustrate that (GCSF)2Lα, unlike the mGCSF and SCF-Lα-GCSF, is irreversibly bound to the surface modified by immobilized GCSF-Receptors. Therefore, to describe binding kinetics in the case of (GCSF)2Lα we have applied advanced kinetic model based on three protein association stages (three-stage kinetics model) in which (GCSF)2Lα forms several different intermediate complexes with GCSF-Receptor. This model precisely describes the time-varying surface concentration of (GCSF)2Lα bound to surface modified by immobilized GCSF-Receptors. In addition to the bioanalytical-aspects possible improvement of GCSF-based drugs is discussed.
The properties of a thin polymer film can be significantly affected by the presence of a penetrant. This can have potential implications for many technological applications, such as protective and ...functional coatings, sensors, microelectronics, surface modification and membrane separations. In situ ellipsometry is a powerful technique for the characterization of a film in contact with a penetrant. The main advantages of ellipsometry include the very high precision and accuracy of this technique, combined with the fact that it is non-intrusive. Recent advances in the speed and automation of the technique have further expanded its application.
This article provides an overview of the research that has been done with in situ UV–vis ellipsometry on penetrant-exposed polymeric films, in the last 15–20 years. The focus is predominantly on films that are not attached covalently to a substrate. Polymer brushes and grafts are therefore excluded. This review addresses a variety of topics, covering instrumental aspects of in situ studies, approaches to data analysis and optical models, reported precision and repeatability, the polymer-penetrant systems that have been studied, the kind of information that has been extracted, and other in situ techniques that have been combined with ellipsometry. Various examples are presented to illustrate different practical approaches, the consequences of the optical properties of the ambient, and the various ways that have been employed to bring polymer films in contact with a penetrant, ranging from simple ex situ-like configurations (i.e., drying studies) to complex high pressure cells. The versatility of in situ ellipsometry is demonstrated by examples of the distinctive phenomena studied, such as film dilation, penetrant diffusion mechanisms, film degradation, electrochemical processes, and the broad variety of polymer-penetrant systems studied (glassy and rubbery polymers, multilayer stacks, etc.). An outlook is given on possible future trends.
PDF
