TY - JOUR A1 - Sachse, René A1 - Bernsmeier, D. A1 - Schmack, R. A1 - Häusler, I. A1 - Hertwig, Andreas A1 - Kraffert, K. A1 - Nissen, J. A1 - Kraehnert, R. T1 - Colloidal bimetallic platinum–ruthenium nanoparticles in ordered mesoporous carbon films as highly active electrocatalysts for the hydrogen evolution reaction N2 - Hydrogen features a very high specific energy density and is therefore a promising candidate for clean fuel from renewable resources. Water electrolysis can convert electrical energy into storable and transportable hydrogen gas. Under acidic conditions, platinum is the most active and stable monometallic catalyst for the hydrogen evolution reaction (HER). Yet, platinum is rare and needs to be used efficiently. Here, we report a synthesis concept for colloidal bimetallic platinum–ruthenium and rhodium–ruthenium nanoparticles (PtRuNP, RhRuNP) and their incorporation into ordered mesoporous carbon (OMC) films. The films exhibit high surface area, good electrical conductivity and well-dispersed nanoparticles inside the mesopores. The nanoparticles retain their size, crystallinity and composition during carbonization. In the hydrogen evolution reaction (HER), PtRuNP/OMC catalyst films show up to five times higher activity per Pt than Pt/C/Nafion® and PtRu/C/Nafion® reference catalysts. KW - Ordered mesoporous carbon KW - Bimetallic noble metal nanoparticles KW - Platinum-ruthenium colloid KW - Electrolysis KW - Hydrogen evolution reaction PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506868 DO - https://doi.org/10.1039/C9CY02285F SN - 2044-4753 VL - 10 IS - 7 SP - 2057 EP - 2068 PB - Royal Society of Chemistry AN - OPUS4-50686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ermilova, Elena A1 - Hertwig, Andreas A1 - Döhring, Thorsten A1 - Stanik, Eva A1 - Cotroneo, Vincenzo A1 - Gibertini, Eugenio T1 - Ellipsometrical characterization of poly-dopamine layers considered for technical applications N2 - Although the organic molecule dopamine (3,4-dihydroxyphenethylamine) is commonly known as the “hormone of happiness”, thin films of poly-dopamine also have interesting technical properties. When produced by dip coating, the self-organizing layers grow in a reproducible thickness of single or multiple molecule monolayers of a few nanometer thickness only. In this work, we introduce a method of determining the layer thickness of poly-dopamine on mirrors for astronomical X-ray telescopes. This work is based on spectroscopic ellipsometry measurements and involves the development of an optical model for the poly-dopamine layers including the dielectric function. Thereby the complex refractive index of the produced layers was determined, covering the range from the ultraviolet to the near infrared spectral region. These measurement results and the corresponding technical challenges are presented in this contribution. Furthermore, an outlook to potential technical applications of this interesting material is given and poly-dopamine layers will make scientist and engineers hopefully happy as an innovative and fascinating technical solution for the future. T2 - SPIE PHOTONICS EUROPE CY - Strasbourg. France DA - 08.04.2024 KW - Polydopamine KW - Thin Solid Layers KW - X-ray optics KW - Spectroscopic Ellipsometry PY - 2024 SN - 978-1-5106-7344-1 DO - https://doi.org/10.1117/12.3015281 VL - 13013 SP - 1 EP - 8 PB - SPIE digital library AN - OPUS4-60954 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Omar, Hassan A1 - Hertwig, Andreas A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Signature of the Adsorbed Layer on the glass transition of thin polymer Films: Broadband Dielectric spectroscopy and related techniques N2 - In well annealed thin polymer films with non-repulsive polymer/substrate interaction with a substrate an irreversibly adsorbed layer is expected to form. These adsorbed layers have shown a great potential for technological applications [1]. However, the growth kinetics and the molecular mobility of the adsorbed layer is still not fully understood. This concerns also the influence of the adsorbed layer on the thickness dependence of the glass transition temperature of thin films. This is partly due to the difficult accessibility of these layers in thin films. Here, the irreversibly adsorbed layers of semi-rigid mail chain polymers like polycarbonate or polysulfone are revealed by solvent-leaching experiments. First, the growth kinetics of these layers is investigated as a function of annealing time. The film thickness, topography and the quality of the adsorbed layer is controlled by Atomic Force Microscopy (AFM). Secondly, the molecular mobility of the adsorbed layer is investigated by Broadband Dielectric Spectroscopy (BDS). A developed nanostructured capacitor arrangement is employed to measure the layer with a free surface. In addition to the dielectric experiments, spectroscopic Ellipsometry measurements are carried out to estimate the glass transition of the thin films. The thickness dependence of the glass transition of the thin films is correlated with the adsorbed layer [2,3]. Acknowledgments D. Hülagü and G. Hidde thanked for the help with the ellipsometry measurements. T2 - 12. Conference on Broabband Dielectric Spectroscopy and its Application CY - Lisbon, Portugal DA - 01.09.2024 KW - Thin films PY - 2024 AN - OPUS4-60959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Hiid, Gundula A1 - Szymoniak, Paulina A1 - Hertwig, Andreas A1 - Schönhals, Andreas T1 - Growth kinetics of the adsorbed layer of poly(bisphenol A carbonate) and its effect on the glass transition behavior in thin films N2 - The glass transition behavior of thin films of poly(bisphenol A carbonate) (PBAC) was studied employing ellipsometry. The glass transition temperature increases with the reduction of the film thickness. This result is attributed to the formation of an adsorbed layer with a reduced mobility compared to bulk PBAC. Therefore, for the first time, the growth kinetics of the adsorbed layer of PBAC was investigated, prepared by leaching samples from a 200 nm thin film which were annealed for several times at three different temperatures. The thickness of each prepared adsorbed layer was measured by multiple scans using atomic force microscopy (AFM). Additionally, an unannealed sample was measured. Comparison of the measurements of the unannealed and the annealed samples provides proof of a pre-growth regime for all annealing temperatures which was not observed for other polymers. For the lowest annealing temperature after the pre-growth stage only a growth regime with a linear time dependence is observed. For higher annealing temperatures the growth kinetics changes from a linear to a logarithmic growth regime at a critical time. At the longest annealing times the films showed signs of dewetting where segments of the adsorbed film were removed from the substrate (dewetting by desorption). The dependence of the surface roughness of the PBAC surface on annealing time also confirmed that the films annealed at highest temperatures for the longest times desorbed from the substrate. KW - Ultra thin polymer films PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574531 DO - https://doi.org/10.1039/D3RA02020G SN - 2046-2069 VL - 13 IS - 21 SP - 14473 EP - 14483 PB - RSC Publishing CY - London AN - OPUS4-57453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mezera, Marek A1 - Alamri, S. A1 - Hendriks, W. A. P. M. A1 - Hertwig, Andreas A1 - Elert, Anna Maria A1 - Bonse, Jörn A1 - Kunze, T. A1 - Lasagni, A. F. A1 - Römer, G. R. B. E. T1 - Hierarchical micro-/nano-structures on polycarbonate via UV pulsed laser processing N2 - Hierarchical micro/-nanostructures were produced on polycarbonate polymer surfaces by employing a two-step UV-laser processing strategy based on the combination of Direct Laser Interference Patterning (DLIP) of gratings and pillars on the microscale (3 ns, 266 nm, 2 kHz) and subsequently superimposing Laser-induced Periodic Surface Structures (LIPSS; 7–10 ps, 350 nm, 100 kHz) which adds nanoscale surface features. Particular emphasis was laid on the influence of the direction of the laser beam polarization on the morphology of resulting hierarchical surfaces. Scanning electron and atomic force microscopy methods were used for the characterization of the hybrid surface structures. Finite-difference time-domain (FDTD) calculations of the laser intensity distribution on the DLIP structures allowed to address the specific polarization dependence of the LIPSS formation observed in the second processing step. Complementary chemical analyzes by micro-Raman spectroscopy and attenuated total reflection Fourier-transform infrared spectroscopy provided in-depth information on the chemical and structural material modifications and material degradation imposed by the laser processing. It was found that when the linear laser polarization was set perpendicular to the DLIP ridges, LIPSS could be formed on top of various DLIP structures. FDTD calculations showed enhanced optical intensity at the topographic maxima, which can explain the dependency of the morphology of LIPSS on the polarization with respect to the orientation of the DLIP structures. It was also found that the degradation of the polymer was enhanced for increasing accumulated fluence levels. KW - Direct laser interference patterning KW - Laser-induced periodic surface structures (LIPSS) KW - Polycarbonate KW - Hierarchical structures KW - Surface functionalization PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509101 DO - https://doi.org/10.3390/nano10061184 SN - 2079-4991 VL - 10(6) IS - Special issue "Laser-generated periodic nanostructures" SP - 1184-1 EP - 1184-19 PB - MDPI CY - Basel AN - OPUS4-50910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas T1 - ELENA: a European project for electrical nanoscale metrology in industry N2 - A competitive advantage in the semiconductors industry is gained through the exploitation of new materials and processes, translating into improved components’ performances. This requires a metrological infrastructure allowing reliable nanoscale characterisation of new materials and devices, particularly in terms of their electrical parameters and properties. Traceability and reliability of nanoscale measurements stand as a major challenge for electrical properties (i.e. resistance, impedance) using conductive atomic force microscopy (C-AFM) and scanning microwave microscopy (SMM) techniques. The non-destructive analysis nature of these two methods is of paramount importance for the characterization of devices and components. However, the state of the art still lacks established measurement protocols, easy to use reference standards, well-defined best practice guides and easy to use 3D models to assess environmental and external stimulation effects. Moreover, costly instrumentation, particularly for high-frequency measurements, still hinders efficient advancements in these directions. ELENA is a 3-years European project that aims at bringing solutions to the aforementioned difficulties. To achieve this goal, the project uses a combination of nanoscale electrodynamic scanning probe methods in combination with optical tools such as spectroscopic ellipsometry on several lateral length scales to determine the electrical properties of layers and small structures. T2 - ICSE-9: The 9th International Conference on Spectroscopic Ellipsometry CY - Beijing, China DA - 2022-05-21 KW - Imaging Ellipsometry KW - Electrical thin layers KW - Scanning Probe methods KW - Hybrid metrology PY - 2022 AN - OPUS4-55464 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas T1 - New analytic ways to characterise mesoporous thin layers used in electrocatalytic water splitting N2 - Mesoporous materials are needed in many applications where a high specific surface area and adsorptive behaviour is needed. Important examples are separation techniques and barrier layers and catalysts. Electrochemical water splitting is the key technology for producing green hydrogen and there is no foreseeable alternative to this process for producing elementary hydrogen from green electrical power. Water electrolysis can be divided into the anodic Oxygen Evolution Reaction (OER) and the cathodic Hydrogen Evolution Reaction (HER). Both processes have to be heavily optimised to a large extent to avoid energy losses caused by overvoltage. The development of electrodes for these processes is especially difficult due to the many boundary conditions. Water splitting is a catalytic as well as electrochemical process. The contact area between the electrolyte and the electrode must be maximised maintaining the stability of the surface. Side reactions must be suppressed, and effective gas transport must be ensured. The whole process has to be tolerant with respect to temperature, harsh chemical conditions from the electrolyte as well as high current densities. We present a hybrid analytical method combining several analytical techniques for determining the properties of thin layers of mixed oxides of the general composition Ir:TiOx. These materials are promising candidates for electrocatalytical top coatings of OER electrodes. To lower the costs of the electrolysers, the main goal is to lower the Ir content retaining the system efficiency. The main properties which are hard to determine are the porous volume fraction and the Ir:Ti element ratio. By a combination of electron microscopy, spectroscopic operando ellipsometry, ellipsometric porosimetry, and other techniques, we can determine key features of mesoporous thin layer materials. We aim to develop operando capable techniques used in process monitoring as well as measurement techniques optimised for accuracy. By developing reference materials, we support long term uptake of our methodology. This work can directly be used for optimising electrocatalytic layers and is a good example for the power of hybrid metrology for improving materials design. T2 - International Conference on Resource Chemistry CY - Alzenau, Germany DA - 11.03.2024 KW - Ellipsometry KW - Electrocatalytic Water Splitting KW - Mesoporous Materials KW - Electron Probe Microanalysis KW - Hydrogen Generation PY - 2024 AN - OPUS4-59764 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas T1 - Ellipsometry as a production measurement tool N2 - Spectroscopic Ellipsometry is an enormously versatile measurement tool for surfaces and thin layers. We discuss the use of ellipsometry in the context of quality control in production processes of eletrconic devices. T2 - Photonics Days Berlin Brandenburg CY - Berlin, Germany DA - 09.10.2023 KW - Ellipsometry KW - Quality control KW - Metrology PY - 2023 AN - OPUS4-59837 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas T1 - Ellipsometry as a tool for electrical metrology - Referencing electrical properties of thin layers with TCO materials N2 - Ellipsometry is a highly valuable technology for bridging different measurement methods. As a fast, highly sensitive, and non-destructive optical technique with low environmental requirements, it is ideal for transporting measurement accuracy and for up-scaling measurements in the production environment. It can be used for highly precise determination of properties, material identity and correctness confirmation, as well as defect detection. Comparable, traceable, and accurate electrical measurements, especially at small scales are one of the biggest challenges in the development of the electrical and electronic devices of the future. In this project, we develop structured thin layer systems of the transparent conductive material indium tin oxide (ITO) to prove the concept of using these systems as standards for conductivity and permittivity. The layers are produced in a reactive magnetron sputtering process from raw ITO targets with additional oxidation achieved by oxygen injection. We present results of a study correlating the coating process conditions with the properties of the final layer material. We found that especially the temperature development during coating is of key importance and determines the layer properties to a large extent. We will discuss questions of homogeneity and reproducibility of the coating processes used. The finished layers undergo lithographic structuring and etching to produce patterns to serve as reference structures for scanning probe electrical measurements. TCOs have a large variety of applications. In this work we also study the usability of ITO for other purposes and investigate the stability of this material under application conditions. T2 - 12th Workshop Ellipsometry 2023 CY - Prague, Czech Republic DA - 18.09.2023 KW - Thin Films KW - Transparent Conductive Oxides KW - Ellipsometry KW - Electrical Properties KW - Nanoelectronics PY - 2023 AN - OPUS4-58410 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas T1 - On the use of spectroscopic imaging ellipsometry for quantification and characterisation of defects in thin films for power electronics N2 - Compound semiconductors (CS) are promising materials for the development of high-power electrical applications. They have low losses, can withstand high temperatures and can operate at very high voltages and currents. This makes them a key technology for the electrification of many high energy applications, especially electromobility and HVDC power lines. The challenge with CS technology is that most of the process technology has to be developed anew to the high standards required by electronic applications. Today, compound semiconductors can be produced in thin layers on top of substrates fabricated from classical crystal growth processes that are already well established. A promising method for this is metal organic vapour phase epitaxy (MOVPE). With this method, many different compounds with semiconducting properties can be synthesized. Additionally, this process technology is a direct thin layer deposition method. Therefore, complex multilayer systems can be generated directly by the deposition process and without the need of doping after growing. There are a number of critical defects that can originate from the deposition process of these thin film devices. Within this project, we intend to develop new correlative imaging and analysis techniques to determine defect types, to quantify defect size and number density, as well as to characterise defects for process optimisation. We report here on the use of spectroscopic ellipsometry and imaging ellipsometry to investigate defects in several different compound semiconductor materials used in high-power electronic devices. The materials we investigated are β-Ga2O3, SiC, GaN, AlN, and AlGaN materials as well as oxidised SiC surfaces. All of these materials have their typical defects and require optimised measurement and analysis schemes for reliable detection and analysis. Spectroscopic ellipsometry is a highly sensitive method for determining the thicknesses and dielectric function of thin layers, yielding potentially a high number of microscopic properties. The combined method between ellipsometry and optical microscopy is called imaging ellipsometry and is especially powerful for the large amount of data it produces. We have analysed defects in SiC- and AlN-based thin film semiconductors as well as characterised the properties of different types of SiO2 layers created on top of SiC monocrystals. We developed ellipsometric models for the data analysis of the different semiconductor materials. If the defects have geometric features, it is useful to combine the ellipsometric analysis with topometry method like interference microscopy and scanning probe microscopy. We have successfully characterised function-critical defects in MOVPE SiC layers and correlated the findings with topography from WLIM measurements. We have developed an imaging ellipsometric measurement methodology that allows to estimate the relative defect area on a surface by a statistical raw data analysis. T2 - EMRS Spring Meeting 2024 - ALTECH 2024 CY - Strasbourg, France DA - 27.05.2024 KW - compound semiconductors KW - Ellipsometry KW - Layer Materials KW - Defect Analysis PY - 2024 AN - OPUS4-61005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolff, M. A1 - Wonneberger, R. A1 - Freiberg, K.E. A1 - Hertwig, Andreas A1 - Bonse, Jörn A1 - Giebeler, L. A1 - Koitzsch, A. A1 - Kunz, C. A1 - Weber, H. A1 - Hufenbach, J.K. A1 - Müller, F.A. A1 - Gräf, S. T1 - Formation of laser-induced periodic surface structures on Zr-based bulk metallic glasses with different chemical composition N2 - Bulk metallic glasses (BMG) are amorphous metal alloys known for their unique physical and mechanical properties. In the present study, the formation of femtosecond (fs) laser-induced periodic surface structures (LIPSS) on the Zr-based BMGs Zr46Cu46Al8, Zr61Cu25Al12Ti2, Zr52.5Cu17.9Al10Ni14.6Ti5 (Vit105) and Zr57Cu15.4Al10Ni12.6Nb5 (Vit106) was investigated as a function of their different chemical composition. For this purpose, LIPSS were generated on the sample surfaces in an air environment by fs-laser irradiation (λ = 1025 nm, τ = 300 fs, frep = 100 kHz). The surface topography was characterized by scanning electron microscopy and atomic force microscopy. Moreover, the impact of LIPSS formation on the structure and chemical surface composition was analyzed before and after fs-laser irradiation by X-ray diffraction and X-ray photoelectron spectroscopy as well as by transmission electron microscopy in combination with energy dispersive X-ray spectroscopy. Despite the different chemical composition of the investigated BMGs, the fs-laser irradiation resulted in almost similar properties of the generated LIPSS patterns. In the case of Zr61Cu25Al12Ti2, Vit105 and Vit106, the surface analysis revealed the preservation of the amorphous state of the materials during fs-laser irradiation. The study demonstrated the presence of a native oxide layer on all pristine BMGs. In addition, fs-laser irradiation results in the formation of laser-induced oxide layers of larger thickness consisting of an amorphous ZrAlCu-oxide. The precise laser-structuring of BMG surfaces on the nanoscale provides a versatile alternative to thermoplastic forming of BMG surfaces and is of particular interest for the engineering of functional material surfaces. KW - Bulk metallic glasses KW - Femtosecond laser KW - Laser-induced periodic surface structures (LIPSS) KW - Chemical analysis KW - Oxidation PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581799 DO - https://doi.org/10.1016/j.surfin.2023.103305 SN - 2468-0230 VL - 42 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-58179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Minenkov, Alexey A1 - Hollweger, Sophia A1 - Duchoslav, Jiri A1 - Erdene-Ochir, Otgonbayar A1 - Weise, Matthias A1 - Ermilova, Elena A1 - Hertwig, Andreas A1 - Schiek, Manuela T1 - Monitoring the Electrochemical Failure of Indium Tin Oxide Electrodes via Operando Ellipsometry Complemented by Electron Microscopy and Spectroscopy N2 - Transparent conductive oxides such as indium tin oxide (ITO) are standards for thin film electrodes, providing a synergy of high optical transparency and electrical conductivity. In an electrolytic environment, the determination of an inert electrochemical potential window is crucial to maintain a stable material performance during device operation. We introduce operando ellipsometry, combining cyclic voltammetry (CV) with spectroscopic ellipsometry, as a versatile tool to monitor the evolution of both complete optical (i.e., complex refractive index) and electrical properties under wet electrochemical operational conditions. In particular, we trace the degradation of ITO electrodes caused by electrochemical reduction in a pH-neutral, water-based electrolyte environment during electrochemical cycling. With the onset of hydrogen evolution at negative bias voltages, indium and tin are irreversibly reduced to the metallic state, causing an advancing darkening, i.e., a gradual loss of transparency, with every CV cycle, while the conductivity is mostly conserved over multiple CV cycles. Post-operando analysis reveals the reductive (loss of oxygen) formation of metallic nanodroplets on the surface. The reductive disruption of the ITO electrode happens at the solid–liquid interface and proceeds gradually from the surface to the bottom of the layer, which is evidenced by cross-sectional transmission electron microscopy imaging and complemented by energy-dispersive X-ray spectroscopy mapping. As long as a continuous part of the ITO layer remains at the bottom, the conductivity is largely retained, allowing repeated CV cycling. We consider operando ellipsometry a sensitive and nondestructive tool to monitor early stage material and property changes, either by tracing failure points, controlling intentional processes, or for sensing purposes, making it suitable for various research fields involving solid–liquid interfaces and electrochemical activity. KW - General Materials Science PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597625 DO - https://doi.org/10.1021/acsami.3c17923 SN - 1944-8252 VL - 16 IS - 7 SP - 9517 EP - 9531 PB - American Chemical Society (ACS) AN - OPUS4-59762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas A1 - François, P. T1 - ELENA Project: Creating a simplified uncertainty calculation for industrial applications N2 - In this workpackage of the ELENA project, we develop a way to express the measurement uncertainty of nanoscale determination of electrical propserties. The method developed aims to be usable for industrial contexts and described in technical documents and standards drafts. Standards and reference samples are used to make traceable measurements available for the end user. T2 - Congrès International de Metrologie CY - Lyon, France DA - 06.03.2023 KW - Nanoscale measurements KW - Electrical properties KW - Optical measurements KW - Surfaces KW - Scanning probe measurements PY - 2023 AN - OPUS4-57155 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grundmann, Jana A1 - Bodermann, Bernd A1 - Ermilova, Elena A1 - Weise, Matthias A1 - Hertwig, Andreas A1 - Klapetek, Petr A1 - Rafighdoost, Jila A1 - Pereira, Silvania F. T1 - Optical and tactile measurements on SiC sample defects N2 - Abstract. In power electronics, compound semiconductors with large bandgaps, like silicon carbide (SiC), are increasingly being used as material instead of silicon. They have a lot of advantages over silicon but are also intolerant of nanoscale material defects, so that a defect inspection with high accuracy is needed. The different defect types on SiC samples are measured with various measurement methods, including optical and tactile methods. The defect types investigated include carrots, particles, polytype inclusions and threading dislocations, and they are analysed with imaging ellipsometry, coherent Fourier scatterometry (CFS), white light interference microscopy (WLIM) and atomic force microscopy (AFM). These different measurement methods are used to investigate which method is most sensitive for which type of defect to be able to use the measurement methods more effectively. It is important to be able to identify the defects to classify them as critical or non-critical for the functionality of the end product. Once these investigations have been completed, the measurement systems can be optimally distributed to the relevant defects in further work to realize a hybrid analysis of the defects. In addition to the identification and classification of defects, such a future hybrid analysis could also include characterizations, e.g. further evaluation of ellipsometric data by using numerical simulations. KW - Compound semiconductors KW - Hybrid metrology KW - Material defects KW - Spectroscopic ellipsometry KW - Scanning probe microscopy KW - White-light interference microscopy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601220 DO - https://doi.org/10.5194/jsss-13-109-2024 SN - 2194-878X VL - 13 IS - 1 SP - 109 EP - 121 PB - Copernicus Publ. CY - Göttingen AN - OPUS4-60122 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas T1 - Characterisation of thin layers of Polydopamine used as functional coatings in X-Ray optics N2 - Polydopamine (PDA) is a biological / biomimetic polymer which has spiked considerable interest in recent years. Its monomer is an important neurotransmitter and it is one of the strongest glues produced by biological organisms. Polydopamine is a candidate for several applications, mainly in the field of biology and medicine, but also - recently - for layer coatings with optical, electrical, and mechanical function. In this work, we investigate PDA layers intended as reflectivity enhancers for mirror surfaces in X-ray astronomical observatories. It has previously been shown, that such X-ray telescopes can be improved by a coating of PDA in the thickness range of several nm. Accurate thickness determination is required to monitor and optimise the coating process. We use spectroscopic ellipsometry to determine first the dielectric function of the polydopamine layers using model coatings of sufficient thickness. This data is then used to accurately determine the layer thickness of much thinner PDA layers. This study resulted in data on the thickness and dielectric function of PDA layers that could lead to a better understanding of the correlation of layer thickness and layer properties depending on the process parameters. T2 - Deutsche Physikalische Gesellschaft - Frühjahrstagung CY - Berlin, Germany DA - 17.03.2024 KW - Polydopamine KW - Thin Solid Layers KW - X-ray optics KW - Spectroscopic Ellipsometry PY - 2024 AN - OPUS4-60955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Ahamadi, Shayan A1 - Hülagü, Deniz A1 - Hidde, Gundula A1 - Hertwig, Andreas A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Investigations of the adsorbed layer of polysulfone: Influence of the thickness of the adsorbed layer on the glass transition of thin films N2 - This work studies the influence of the adsorbed layer on the glass transition of thin films of polysulfone. Therefore, the growth kinetics of the irreversibly adsorbed layer of polysulfone on silicon substrates was first investigated using the solvent leaching approach, and the thickness of the remaining layer was measured with atomic force microscopy. Annealing conditions before leaching were varied in temperature and time (0–336 h). The growth kinetics showed three distinct regions: a pre-growth step where it was assumed that phenyl rings align parallel to the substrate at the shortest annealing times, a linear growth region, and a crossover from linear to logarithmic growth observed at higher temperatures for the longest annealing times. No signs of desorption were observed, pointing to the formation of a strongly adsorbed layer. Second, the glass transition of thin polysulfone films was studied in dependence on the film thickness using spectroscopic ellipsometry. Three annealing conditions were compared: two with only a tightly bound layer formed in the linear growth regime and one with both tightly bound and loosely adsorbed layers formed in the logarithmic growth regime. The onset thickness and increase in the glass transition temperature increases with annealing time and temperature. These differences were attributed to the distinct conformations of the formed adsorbed layers. KW - Glass transition KW - Adsorbed Layer PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607701 DO - https://doi.org/10.1063/5.0223415 SN - 0021-9606 VL - 161 IS - 5 SP - 1 EP - 12 PB - AIP Publishing AN - OPUS4-60770 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hertwig, Andreas A1 - Ermilova, Elena T1 - Optical constants of a single AlN layer on Si N2 - Spectroscopic ellipsometry was used to determine the thickness and dielectric function of a Aluminium Nitride (AlN) layer on a Si wafer. The layer was determined to be 170 nm thick. The layer was provided by AIXTRON and manufactured by means of MOVPE. The data was created using a M2000DI spectroscopic ellipsometer from Woollam Co. Inc. Analysis was done using the CompleteEASE software. The model used is a multi-peak oscillator model for the AlN layer. The data resembles common database values for the material AlN. KW - Aluminium nitride KW - Thin solid layers KW - Spectroscopic ellipsometry KW - Compund semiconductors KW - MOVPE PY - 2024 UR - https://zenodo.org/records/12743500 DO - https://doi.org/10.5281/zenodo.12743499 PB - Zenodo CY - Geneva AN - OPUS4-60661 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -