TY - JOUR A1 - Mennicken, Max A1 - Peter, Sophia Katharina A1 - Kaulen, Corinna A1 - Simon, Ulrich A1 - Karthäuser, Silvia T1 - Impact of device design on the electronic and optoelectronic properties of integrated Ru-terpyridine complexes JF - Beilstein journal of nanotechnology N2 - The performance of nanoelectronic and molecular electronic devices relies strongly on the employed functional units and their addressability, which is often a matter of appropriate interfaces and device design. Here, we compare two promising designs to build solid-state electronic devices utilizing the same functional unit. Optically addressable Ru-terpyridine complexes were incorporated in supramolecular wires or employed as ligands of gold nanoparticles and contacted by nanoelectrodes. The resulting small-area nanodevices were thoroughly electrically characterized as a function of temperature and light exposure. Differences in the resulting device conductance could be attributed to the device design and the respective transport mechanism, that is, thermally activated hopping conduction in the case of Ru-terpyridine wire devices or sequential tunneling in nanoparticle-based devices. Furthermore, the conductance switching of nanoparticle-based devices upon 530 nm irradiation was attributed to plasmon-induced metal-to-ligand charge transfer in the Ru-terpyridine complexes used as switching ligands. Finally, our results reveal a superior device performance of nanoparticle-based devices compared to molecular wire devices based on Ru-terpyridine complexes as functional units. KW - Ru-terpyridine wires KW - conductance switching KW - gold nanoparticles KW - nanoelectronic devices KW - optical addressing Y1 - 2022 U6 - https://doi.org/10.3762/bjnano.13.16 VL - 13 SP - 219 EP - 229 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften ER - TY - JOUR A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hausladen, Matthias A1 - Wohlfartsstätter, Dominik A1 - Edler, Simon A1 - Bachmann, Michael A1 - Pahlke, Andreas A1 - Schreiner, Rupert A1 - Hansch, Walter T1 - Quantitative Field Emission Imaging for Studying the Doping-Dependent Emission Behavior of Silicon Field Emitter Arrays JF - Micromachines N2 - Field emitter arrays (FEAs) are a promising component for novel vacuum micro- and nanoelectronic devices, such as microwave power amplifiers or fast-switching X-ray sources. However, the interrelated mechanisms responsible for FEA degradation and failure are not fully understood. Therefore, we present a measurement method for quantitative observation of individual emission sites during integral operation using a low-cost, commercially available CMOS imaging sensor. The emission and degradation behavior of three differently doped FEAs is investigated in current-regulated operation. The measurements reveal that the limited current of the p-doped emitters leads to an activation of up to 55% of the individual tips in the array, while the activation of the n-type FEA stopped at around 30%. This enhanced activation results in a more continuous and uniform current distribution for the p-type FEA. An analysis of the individual emitter characteristics before and after a constant current measurement provides novel perspectives on degradation behavior. A burn-in process that trims the emitting tips to an integral current-specific ideal field enhancement factor is observed. In this process, blunt tips are sharpened while sharp tips are dulled, resulting in homogenization within the FEA. The methodology is described in detail, making it easily adaptable for other groups to apply in the further development of promising FEAs. Y1 - 2023 U6 - https://doi.org/10.3390/mi14112008 VL - 14 IS - 11 PB - MDPI ER - TY - JOUR A1 - Müller, Max A1 - Weigl, Stefan A1 - Müller-Williams, Jennifer A1 - Lindauer, Matthias A1 - Rück, Thomas A1 - Jobst, Simon A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Comparison of photoacoustic spectroscopy and cavity ring-down spectroscopy for ambient methane monitoring at Hohenpeißenberg JF - Atmospheric Measurement Techniques N2 - With an atmospheric concentration of approximately 2000 parts per billion (ppbV, 10−9), methane (CH4) is the second most abundant greenhouse gas (GHG) in the atmosphere after carbon dioxide (CO2). The task of long-term and spatially resolved GHG monitoring to verify whether climate policy actions are effective is becoming more crucial as climate change progresses. In this paper we report the CH4 concentration readings of our photoacoustic (PA) sensor over a 5 d period at Hohenpeißenberg, Germany. As a reference device, a calibrated cavity ring-down spectrometer, Picarro G2301, from the meteorological observatory of the German Weather Service (DWD) was employed. Trace gas measurements with photoacoustic instruments promise to provide low detection limits at comparably low costs. However, PA devices are often susceptible to cross-sensitivities related to fluctuating environmental conditions, e.g. ambient humidity. The obtained results show that for PA sensor systems non-radiative relaxation effects induced by varying humidity are a non-negligible factor. Applying algorithm compensation techniques, which are capable of calculating the influence of non-radiative relaxation effects on the photoacoustic signal, increase the accuracy of the photoacoustic sensor significantly. With an average relative deviation of 1.11 % from the G2301, the photoacoustic sensor shows good agreement with the reference instrument. Y1 - 2023 U6 - https://doi.org/10.5194/amt-16-4263-2023 SN - 1867-8548 VL - 16 IS - 18 SP - 4263 EP - 4270 PB - Copernicus Publications ER - TY - JOUR A1 - Goldschmidt, Jens A1 - Moser, Elisabeth A1 - Nitzsche, Leonard A1 - Bierl, Rudolf A1 - Wöllenstein, Jürgen T1 - Improving the performance of artificial neural networks trained on synthetic data in gas spectroscopy – a study on two sensing approaches JF - tm - Technisches Messen N2 - Artificial neural networks (ANNs) are used in quantitative infrared gas spectroscopy to predict concentrations on multi-component absorption spectra. Training of ANNs requires vast amounts of labelled training data which may be elaborate and time consuming to obtain. Additional data can be gained by the utilization of synthetically generated spectra, but at the cost of systematic deviations to measured data. Here, we present two approaches to train ANNs with a combination of comparatively small, measured data sets and synthetically generated data. For the first approach a neural network is trained hybridly with synthetically generated infrared absorption spectra of mixtures of N2O and CO and measured zero-gas spectra, taken with a mid-infrared dual comb spectrometer. This improves the mean absolute error (MAE) of the network predictions from 0.46 to 0.01 ppmV and 0.24 to 0.01 ppmV for the concentration predictions of N2O and CO respectively for zero-gas measurements which was previously observed for training with purely synthetic data. At the same time a similar performance on spectra from gas mixtures of 0–100 ppmV N2O and 0 to 60 ppmV CO was achieved. For the second approach an ANN pre-trained on synthetic infrared spectra of mixtures of acetone and ethanol is retrained on a small dataset consisting of 26 spectra taken with a mid-infrared photoacoustic spectrometer. In this case the MAE for the concentration predictions of ethanol and acetone are improved by 45 % and 20 % in comparison to purely synthetic training. This shows the capability of using synthetically generated data to train ANNs in combination with small amounts of measured data to further improve neural networks for gas sensing and the transferability between different sensing approaches. N2 - Künstliche neuronale Netze werden in der quantitativen Infrarot-Gasspektroskopie eingesetzt, um Gaskonzentrationen in Multi-Komponenten-Absorptionsspektren vorherzusagen. Das Training von künstlichen neuronalen Netzen benötigt große Mengen an Trainingsdaten, was mit einem hohen Arbeits- und Zeitaufwand verbunden ist. Zusätzliche Trainingsdaten können durch synthetisch generierte Spektren gewonnen werden, sind jedoch mit systematischen Abweichungen zu tatsächlich gemessenen Daten verbunden. In dieser Arbeit werden zwei Ansätze präsentiert, um künstliche neuronale Netze mit einer Kombination aus vergleichsweise kleinen, gemessenen Datensätzen und synthetisch erzeugten Daten zu trainieren. Für den ersten Ansatz wird das neuronale Netz hybrid mit synthetisch erzeugten Infrarot-Absorptionsspektren von Mischungen aus N2O und CO und gemessenen Null-Gas-Spektren trainiert, welche mit einem Doppel-Kamm-Spektrometer im Mittelinfraroten aufgenommen wurden. Dieses Vorgehen verbessert den mittleren, absoluten Fehler der Netzvorhersagen von 0,46 auf 0,01 ppmV und 0,24 auf 0,01 ppmV für N2O bzw. für CO für Null-Gas-Messungen, im Vergleich zu den Vorhersagen des neuronalen Netzes, welches nur mit synthetisch erzeugten Daten trainiert wurde. Gleichzeitig zeigte das hybrid trainierte Netz eine gleichbleibende Performance für Konzentrationsvorhersagen für Spektren aus Gasmischungen von 0 bis 100 ppmV N2O und 0 bis 60 ppmV CO. Für den zweiten Ansatz wird ein neuronales Netz, welches bereits mit synthetischen erzeugten Infrarotspektren von Mischungen aus Aceton und Ethanol trainiert wurde, erneut auf einem kleinen gemessenen Datensatz bestehend aus 26 Spektren trainiert, welche mit einem photoakustischen Spektrometer im mittleren Infrarot aufgenommen wurden. In diesem Fall hat sich der mittlere absolute Fehler der Konzentrationsvorhersage für Ethanol und Aceton um 45 % bzw. 20 % im Vergleich zu einem rein synthetischen Training verbessert. Das zeigt das Potential synthetisch erzeugte Daten für das Training von künstlichen neuronalen Netzen in Kombination mit kleinen gemessenen Datensätzen zu nutzen, um neuronale Netze für den Einsatz im Bereich der Gassensorik zu verbessern und gleichzeitig die Übertragbarkeit der Methodik auf verschiedene Messansätze. Y1 - 2023 U6 - https://doi.org/10.1515/teme-2023-0051 PB - Oldenbourg Wissenschaftsverlag ET - Online veröffentlicht ER - TY - JOUR A1 - Zifarelli, Andrea A1 - Cantatore, Aldo Francesco Pio A1 - Sampaolo, Angelo A1 - Mueller, Max A1 - Rueck, Thomas A1 - Hoelzl, Christine A1 - Rossmadl, Hubert A1 - Patimisco, Pietro A1 - Spagnolo, Vincenzo T1 - Multivariate analysis and digital twin modelling: Alternative approaches to evaluate molecular relaxation in photoacoustic spectroscopy JF - Photoacoustics N2 - A comparative analysis of two different approaches developed to deal with molecular relaxation in photoacoustic spectroscopy is here reported. The first method employs a statistical analysis based on partial least squares regression, while the second method relies on the development of a digital twin of the photoacoustic sensor based on the theoretical modelling of the occurring relaxations. Methane detection within a gas matrix of synthetic air with variable humidity level is selected as case study. An interband cascade laser emitting at 3.345 µm is used to target methane absorption features. Two methane concentration ranges are explored targeting different absorptions, one in the order of part-per-million and one in the order of percent, while water vapor absolute concentration was varied from 0.3 % up to 2 %. The results achieved employing the detection techniques demonstrated the possibility to efficiently retrieve the target gas concentrations with accuracy > 95 % even in the case of strong influence of relaxation effects. KW - digital twin model KW - methane detection over a wide concentration range KW - multivariate analysis KW - Partial Least Squares Regression KW - QEPAS sensor KW - relaxation effects photoacoustic spectroscopy KW - water vapor influence on relaxation Y1 - 2023 U6 - https://doi.org/10.1016/j.pacs.2023.100564 SN - 2213-5979 VL - 33 PB - Elsevier ER - TY - JOUR A1 - Jobst, Simon A1 - Recum, Patrick A1 - Écija-Arenas, Ángela A1 - Moser, Elisabeth A1 - Bierl, Rudolf A1 - Hirsch, Thomas T1 - Semi-Selective Array for the Classification of Purines with Surface Plasmon Resonance Imaging and Deep Learning Data Analysis JF - ACS sensors N2 - In process analytics or environmental monitoring, the real-time recording of the composition of complex samples over a long period of time presents a great challenge. Promising solutions are label-free techniques such as surface plasmon resonance (SPR) spectroscopy. They are, however, often limited due to poor reversibility of analyte binding. In this work, we introduce how SPR imaging in combination with a semi-selective functional surface and smart data analysis can identify small and chemically similar molecules. Our sensor uses individual functional spots made from different ratios of graphene oxide and reduced graphene oxide, which generate a unique signal pattern depending on the analyte due to different binding affinities. These patterns allow four purine bases to be distinguished after classification using a convolutional neural network (CNN) at concentrations as low as 50 μM. The validation and test set classification accuracies were constant across multiple measurements on multiple sensors using a standard CNN, which promises to serve as a future method for developing online sensors in complex mixtures. KW - surface plasmon resonance imaging KW - functional surface KW - graphene oxide KW - reduced graphene oxide KW - 2D materials KW - pattern recognition KW - small-molecule sensing Y1 - 2023 U6 - https://doi.org/10.1021/acssensors.3c01114 VL - 8 IS - 9 SP - 3530 EP - 3537 PB - American Chemical Society ER - TY - JOUR A1 - Zahner, Th A1 - Schreiner, Rupert A1 - Stierstorfer, R. A1 - Kus, O. A1 - Li, S. T. A1 - Roessler, R. A1 - Pedarnig, J. D. A1 - Bäuerle, D. A1 - Lengfellner, H. T1 - Off-diagonal Seebeck effect and anisotropic thermopower in Bi2Sr2CaCu2O8 thin films JF - Europhysics Letters N2 - The anisotropy ΔS of the thermopower in thin films of the high-Tc superconductor Bi2Sr2CaCu2O8 is investigated using off–c-axis epitaxial film growth and the off-diagonal Seebeck effect. The measurements represent a new method for the investigation of anisotropic transport properties in solids, taking advantage of the availability of oriented grown crystalline thin films instead of using bulk crystals. First results for the temperature dependence ΔS(T) in Bi2Sr2CaCu2O8 thin films are presented and described within a two-band model. Subjecting the films to heat treatments in different gases at relatively low temperatures, ΔS could reversibly be changed in a wide range. Y1 - 1997 U6 - https://doi.org/10.1209/epl/i1997-00521-4 VL - 40 IS - 6 SP - 673 EP - 678 PB - IOP Sciences ER - TY - JOUR A1 - Schreiner, Rupert A1 - Schweizer, Heinz C. T1 - High-frequency operation of 1.57-μm laterally coupled distributed feedback lasers with self-aligned ohmic contacts and nickel surface gratings JF - IEEE Journal of Selected Topics in Quantum Electronics N2 - Laterally coupled distributed feedback lasers with self-aligned ohmic contacts show the advantage of a considerably simplified fabrication process. These lasers exhibit superior spectral properties with full benefit from the gain coupling mechanism. Side-mode suppression ratios up to 55- and 3-dB bandwidths beyond 15 GHz were obtained for these devices. KW - Distributed feedback devices KW - Optical coupling KW - Laser feedback KW - Ohmic contacts KW - Nickel KW - Surface emitting lasers KW - Gratings KW - Optical device fabrication KW - Mechanical factors KW - Bandwidth Y1 - 2003 U6 - https://doi.org/10.1109/JSTQE.2003.819469 VL - 9 IS - 5 SP - 1179 EP - 1182 PB - IEEE ER - TY - JOUR A1 - Cheong, Kuan Yew A1 - Aw, Kean A1 - Karimov, Khasan S. A1 - Zhao, Feng A1 - Mahroof-Tahir, Mohammad A1 - Schreiner, Rupert T1 - Advances in Smart Materials and Applications JF - Advances in Materials Science and Engineering N2 - This is one of a series of special issues published in Advances in Materials Science and Engineering, focusing on the latest advances of smart materials and their applications. Evolution of engineering materials is strongly depending on the growing transformation of complexity in engineering products. New materials being designed are required to provide specific properties and demonstrate certain functional characteristics by manipulating their dimension, chemistry, and structure through various advanced technologies. Therefore, “smartness” of a material has become the topic of interest. Properties of smart materials may change accordingly to the applied external stimuli. Under the direction of the editorial team, we showcase advances of organic and inorganic based smart materials and their applications in areas of specific interest such as energy, environment, and health. A total of 9 articles are published in this special issue. Six articles are focused on production, synthesis, and optimization of smart materials; and the remaining are dedicated to application of smart materials. Y1 - 2014 U6 - https://doi.org/10.1155/2014/517342 PB - Hindawi ER - TY - JOUR A1 - Schreiner, Rupert A1 - Wiedmann, J. A1 - Coenning, W. A1 - Porsche, J. A1 - Gentner, Jean-Louis A1 - Berroth, Manfred A1 - Scholz, Ferdinand A1 - Schweizer, H. T1 - Fabrication approach for antiphase narrow linewidth complex coupled 1.55 μm DFB lasers JF - Electronics Letters N2 - A new method for fabricating narrow linewidth antiphase complex coupled MQW DFB lasers by periodically etching the active layer and quartemary InGaAsP overgrowth is reported. The minimum linewidth for a 375 µm long ridge waveguide laser is only 250 kHz at an optical output power of 4 mW. KW - etching KW - optical fabrication KW - quantum well lasers KW - ridge waveguides KW - distributed feedback lasers Y1 - 1999 U6 - https://doi.org/10.1049/el:19990132 SN - 0013-5194 VL - 35 IS - 2 SP - 146 EP - 148 PB - The Institution of Engineering and Technology IET ER - TY - JOUR A1 - Schreiner, Rupert A1 - Körbl, M. A1 - Gräbeldinger, H. A1 - Gentner, Jean-Louis A1 - Schweizer, H. T1 - Laterally gain-coupled 1.57 [micro sign]m DFB lasers with chromium surface grating and self-aligned Ti/Pt/Au ohmic contact JF - Electronics Letters N2 - A simple method for fabricating gain coupled DFB lasers with lateral surface chromium Bragg gratings and self-aligned low capacitance ohmic contacts is reported. These InGaAsP/InP lasers show monomode emission with a sidemode suppression ratio of 40 dB. For 243 µm long devices a continuous wave threshold current of 17 mA was measured at room temperature. KW - Bragg gratings KW - platinum KW - chromium KW - ohmic contacts KW - titanium KW - distributed feedback lasers KW - gold Y1 - 2000 U6 - https://doi.org/10.1049/el:20000500 SN - 0013-5194 VL - 36 IS - 7 SP - 636 EP - 637 PB - The Institution of Engineering and Technology, IET ER - TY - JOUR A1 - Schreiner, Rupert A1 - Naegele, Peter A1 - Körbl, M. A1 - Groning, A. A1 - Gentner, Jean-Louis A1 - Schweizer, Heinz C. T1 - Monolithically integrated tunable laterally coupled distributed-feedback lasers JF - Photonics Technology Letters N2 - A new method for fabrication of tunable InGaAsP-InP single-mode lasers without epitaxial overgrowth is reported. These devices show the advantage of a considerably simplified fabrication process compared to conventional tunable laser types. The lasers comprise an active Bragg reflector integrated with an uncorrugated separately pumped gain region. By adjusting the current through the Bragg reflector, the wavelength can be tuned between 1590.8 and 1595.2 nm. KW - Tunable circuits and devices KW - Optical coupling KW - Laser tuning KW - Etching KW - Pump lasers KW - Laser feedback KW - Optical device fabrication KW - Distributed feedback devices KW - Gratings KW - Fiber lasers Y1 - 2001 U6 - https://doi.org/10.1109/68.969880 VL - 13 IS - 12 SP - 1277 EP - 1279 PB - IEEE ER - TY - JOUR A1 - Denk, Alexander A1 - Schüngel, Verena A1 - Weber, Stefka A1 - Kaulen, Corinna T1 - Heimexperiment und Online-Dokumentation : Praktische Ausbildung in den MINT-Fächern JF - Chemie in unserer Zeit N2 - Die Anleitung zum selbständigen wissenschaftlichen Arbeiten ist ein fester Bestandteil in der naturwissenschaftlichen Ausbildung, der im letzten Jahr durch Distanz‐Unterricht stark vernachlässigt wurde. Wir stellen hier einen Ansatz vor, bei dem Studierende zu Hause mit Alltagsgegenständen in Teilaufgaben die Aktivität von Hefe in Abhängigkeit von Temperatur und Substrat untersucht haben. Die Ergebnisse des gesamten Kurses wurden in einem Google‐Dokument gesammelt und zentral ausgewertet. Gleichzeitig fand ein Erfahrungsaustausch unter den Lernenden statt und Probleme konnten öffentlich diskutiert werden. Darüber hinaus wurden grundlegende Fähigkeiten wie Beobachten, Protokollieren und detailgetreues Berichten geübt. Die Online‐Dokumentation und ‐Erfassung der Ergebnisse stellt somit eine geeignete Methode dar, die Durchführung von Heimexperimenten zu aktivieren und zu koordinieren. N2 - Instruction in independent scientific work is an integral part of science education that has been severely neglected in the past year due to distance teaching. Here, we present an approach in which students used everyday objects to investigate the activity of yeast as a function of temperature and substrate in subtasks at home. The results of the whole course were collected in a Google document and centrally analyzed. At the same time, the learners were asked to upload their experimental reports with photos to a wiki. This enabled an exchange of experiences among the learners and problems could be discussed publicly. Furthermore, basic skills like observing, logging and detailed reporting were practiced. Online documentation and recording of results is thus a suitable method to activate and coordinate the implementation of home experiments. Y1 - 2023 U6 - https://doi.org/10.1002/ciuz.202100018 PB - Wiley-VCH ER - TY - JOUR A1 - George, Wolfgang Michael A1 - Allert, R. A1 - Weber, Karsten T1 - Versorgung Sterbender im Krankenhaus Ein vom G-BA-Innovationsfonds gefördertes Projekt reduziert nicht indizierte Verlegungen JF - KU-Gesundheitsmanagement N2 - Würdevolles Sterben muss an jedem Ort möglich sein, auch im Krankenhaus, und hier nicht nur auf einer Palliativstation. Immer noch kommt es am Lebensende zu unnötigen, nicht dem Patientenwohl dienenden, Verlegungen vom Heim oder der eigenen Wohnung in das Krankenhaus, vom Krankenhaus bspw. in ein Hospiz oder innerhalb des Krankenhauses von einer Normal- auf die Intensivstation. Damit die Zahl vermeidbarer Verlegungen im Krankenhaus reduziert wird, wurden im Rahmen eines Projektes zur Versorgungsforschung (Avenue-Pal), gefördert über den Gemeinsamen Bundesausschuss aus dem Innovationsfonds des Bundes, Entscheidungshilfen erarbeitet. Y1 - 2021 SN - 2510-8409 VL - 90 SP - 24 EP - 27 PB - Mediengruppe Oberfranken - Fachverlage CY - Kulmbach ER - TY - JOUR A1 - Bachmann, Michael A1 - Düsberg, Felix A1 - Pahlke, Andreas A1 - Edler, Simon A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hausladen, Matthias A1 - Buchner, Philipp A1 - Schreiner, Rupert T1 - The “LED‐version” of the electron gun: An electron source for operation in ambient pressure environments based on silicon field emitter arrays JF - Vakuum in Forschung und Praxis N2 - We report on our progress to develop and optimize electron sources for practical applications. A simple fabrication process is introduced based on a wafer dicing saw and a wet chemical etch step without the need for a clean room. Due to the formation of crystal facets the samples show a homogeneous geometry throughout the array. Characterization techniques are developed to systematically compare various arrays. A very defined measurement procedure based on current controlled IV-sweeps as well as lifetime measurements at various currents is proposed. To investigate the current distribution in the array a commercial CMOS detector is used and shows the potential for in depth analysis of the arrays. Finally, a compact hermetically sealed housing is presented enabling electron generation in atmospheric pressure environments. Y1 - 2023 U6 - https://doi.org/10.1002/vipr.202300801 VL - 35 IS - 3 SP - 32 EP - 37 PB - Wiley ER - TY - JOUR A1 - Pangerl, Jonas A1 - Moser, Elisabeth A1 - Müller, Max A1 - Weigl, Stefan A1 - Jobst, Simon A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - A sub-ppbv-level Acetone and Ethanol Quantum Cascade Laser Based Photoacoustic Sensor– Characterization and Multi-Component Spectra Recording in Synthetic Breath JF - Photoacoustics N2 - Trace gas analysis in breath is challenging due to the vast number of different components. We present a highly sensitive quantum cascade laser based photoacoustic setup for breath analysis. Scanning the range between 8263 and 8270 nm with a spectral resolution of 48 pm, we are able to quantify acetone and ethanol within a typical breath matrix containing water and CO2. We photoacoustically acquired spectra within this region of mid-infra-red light and prove that those spectra do not suffer from non-spectral interferences. The purely additive behavior of a breath sample spectrum was verified by comparing it with the independently acquired single component spectra using Pearson and Spearman correlation coefficients. A previously presented simulation approach is improved and an error attribution study is presented. With a 3σ detection limit of 6.5 ppbv in terms of ethanol and 250 pptv regarding acetone, our system is among the best performing presented so far. KW - Acetone KW - Breath analysis KW - Photoacoustic spectroscopy KW - Quantum cascade laser KW - Spectral simulation Y1 - 2023 U6 - https://doi.org/10.1016/j.pacs.2023.100473 SN - 2213-5979 N1 - Corresponding author: Jonas Pangerl VL - 30 SP - 1 EP - 12 PB - Elsevier ER - TY - JOUR A1 - Schmidt, Oliver G. A1 - Denker, Ullrich A1 - Dashiell, Michael W. A1 - Jin-Phillipp, Neng Yun A1 - Eberl, Karl A1 - Schreiner, Rupert A1 - Gräbeldinger, Hedwig A1 - Schweizer, Heinz C. A1 - Christiansen, Silke H. A1 - Ernst, Frank T1 - Laterally aligned Ge/Si islands: a new concept for faster field-effect transistors JF - Materials Science and Engineering B N2 - Self-assembled and coherently strained Ge dots were grown on a Si/SiGe superlattice, which was deposited on a flat Si(001) substrate surface patterned with a regular array of straight trenches. The superlattice translates the surface modulation of the substrate into a strain-field modulation, which causes the Ge dots on its surface to form along straight lines above the buried trenches. This approach provides self-assembled Ge dots with excellent lateral periodicity, which might be useful for fabricating dot-based field-effect-transistors (DotFETs). Here, we propose the concept of a modulation-doped p-channel DotFET (p-MOD-DotFET). The p-MOD-DotFET relies on embedded Ge-rich nanostructures, which provide p-channels through the Ge-rich dots. A high Ge concentration in the dots is desirable in order to exploit the high hole mobility of Ge-rich material. We show that the commonly observed Si–Ge intermixing during Si capping of Ge dots can be suppressed by overgrowing the islands at low temperature. KW - Field-effect transistor KW - Self-assembly islands KW - CMOS KW - MOSFET KW - MOFDET alignment KW - Modulation Y1 - 2002 U6 - https://doi.org/10.1016/S0921-5107(01)00810-8 SN - 1873-4944 SN - 0921-5107 VL - 89 IS - 1-3 SP - 101 EP - 105 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Rück, Thomas A1 - Müller, Max A1 - Jobst, Simon A1 - Weigl, Stefan A1 - Pangerl, Jonas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Digital Twin of a Photoacoustic Trace Gas Sensor for Monitoring Methane in Complex Gas Compositions JF - Sensors and Actuators B: Chemical N2 - The digitalization of industrial processes requires smart sensor systems. Photoacoustic spectroscopy is well suited for this purpose as it allows for small-sized and low-cost trace gas analysis. However, the method is susceptible to changes in measurement conditions and standard calibration routines often fail to correct for all changes. We therefore created a Digital Twin (DT) of a photoacoustic trace gas sensor for methane and evaluated it regarding variations in gas composition (CH4, N2, O2, CO2, H2O), temperature and pressure. With a mean absolute percentage error of 0.8 % the accuracy of the sensor after DT compensation significantly exceeds the 24 % achieved based on standard calibration in nitrogen. For the first time, we can fully analytically compute the photoacoustic signal under moderate ambient conditions with an error in the ppbV range by taking a holistic approach. Assuming knowledge of the underlying energy transfer processes, the model of this Digital Twin can be adapted to any microphone based photoacoustic sensor for monitoring any analyte species. KW - Digital Twin KW - Photoacoustic spectroscopy KW - Smart sensor KW - Acoustic resonance monitoring KW - CoNRad KW - Calibration-free method Y1 - 2023 U6 - https://doi.org/10.1016/j.snb.2022.133119 N1 - Preprint unter: https://doi.org/10.2139/ssrn.4215170 ; https://opus4.kobv.de/opus4-oth-regensburg/frontdoor/index/index/docId/5417 IS - 378 ER - TY - JOUR A1 - Reinker, Lukas A1 - Bläsing, Dominic A1 - Bierl, Rudolf A1 - Ulbricht, Sabina A1 - Dendorfer, Sebastian T1 - Correlation of Acceleration Curves in Gravitational Direction for Different Body Segments during High-Impact Jumping Exercises JF - sensors N2 - Osteoporosis is a common disease of old age. However, in many cases, it can be very well prevented and counteracted with physical activity, especially high-impact exercises. Wearables have the potential to provide data that can help with continuous monitoring of patients during therapy phases or preventive exercise programs in everyday life. This study aimed to determine the accuracy and reliability of measured acceleration data at different body positions compared to accelerations at the pelvis during different jumping exercises. Accelerations at the hips have been investigated in previous studies with regard to osteoporosis prevention. Data were collected using an IMU-based motion capture system (Xsens) consisting of 17 sensors. Forty-nine subjects were included in this study. The analysis shows the correlation between impacts and the corresponding drop height, which are dependent on the respective exercise. Very high correlations (0.83–0.94) were found between accelerations at the pelvis and the other measured segments at the upper body. The foot sensors provided very weak correlations (0.20–0.27). Accelerations measured at the pelvis during jumping exercises can be tracked very well on the upper body and upper extremities, including locations where smart devices are typically worn, which gives possibilities for remote and continuous monitoring of programs. KW - osteoporosis KW - inertial measurement units KW - wearable motion-tracking sensors KW - high-impact exercisess Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-58217 N1 - Corresponding author: Lukas Reinker N1 - This work was supported by the Bavarian Academic Forum [BayWISS-Verbundkolleg Gesundheit] and the DHZK fond for behavioral cardiovascular diseases [Behaviorale kardiovaskuläre Erkrankungen; grand number: 81Z0400105]. VL - 23 IS - 4 PB - MDPI CY - Basel ER - TY - JOUR A1 - Pirker, Luka A1 - Ławrowski, Robert Damian A1 - Schreiner, Rupert A1 - Remškar, Maja A1 - Višić, Bojana T1 - MoₓWₓ₋₁S₂ Nanotubes for Advanced Field Emission Application JF - Advanced Functional Materials N2 - Transition metal dichalcogenide (TMDC) nanotubes complement the field of low-dimensional materials with their quasi-1D morphology and a wide set of intriguing properties. By introducing different transition metals into the crystal structure, their properties can be tailored for specific purpose and applications. Herein, the characterization and a subsequent preparation of single-nanotube field emission devices of MoxWx-1S2 nanotubes prepared via the chemical vapor transport reaction is presented. Energy-dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray diffraction indicate that the molybdenum and tungsten atoms are randomly distributed within the crystal structure and that the material is highly crystalline. High resolution transmission electron microscopy and electron diffraction (ED) patterns further corroborate these findings. A detailed analysis of the ED patterns from an eight-layer nanotube reveal that the nanotubes grow in the 2H structure, with each shell consists of one bilayer. The work function of the nanotubes is comparable to that of pure MoS2 and lower of pure WS2 NTs, making them ideal candidates for field emission applications. Two devices with different geometrical setup are prepared and tested as field emitters, showing promising results for single nanotube field emission applications. Y1 - 2023 U6 - https://doi.org/10.1002/adfm.202213869 SN - 1616-3028 N1 - Early View. Online Version of Record before inclusion in an issue SP - 1 EP - 8 PB - Wiley ER - TY - JOUR A1 - Bornmann, Benjamin A1 - Mingels, Stephan A1 - Dams, Florian A1 - Prommesberger, Christian A1 - Schreiner, Rupert A1 - Lützenkirchen-Hecht, Dirk A1 - Müller, Günter T1 - Electron spectrometer in adjustable triode configuration for photo-induced field emission measurements JF - The Review of scientific instruments N2 - We have constructed a new ultrahigh vacuum apparatus with a triode configuration for the systematic investigation of photo-induced field emission (PFE) from metallic or semiconducting cathodes. These are exposed to electric fields up to 400 MV∕m and laser irradiation by means of hole or mesh gates. Cathodes and gates are in situ exchangeable and adjustable with high precision to ensure a homogeneous extraction of electrons which are partially transmitted to the fixed electron spectrometer. Its hemispherical sector analyzer provides an energy resolution limit of 8 meV. The commissioning of the measurement system has been performed with a tungsten needle. Its temperature showed up in the high-energy tail of the electron spectrum, while its work function was derived from the spectral low-energy part combined with the integral current-voltage curve. First PFE measurements on B-doped Si-tip arrays yielded a small field emission current increase under green laser illumination. A shift and splitting of the energy spectra was observed which revealed different emission regimes as well as the photosensitivity of the cathode due to carrier excitation into the conduction band. For the full exploitation of the PFE system, a tunable laser over a wide eV-range is required. Y1 - 2012 U6 - https://doi.org/10.1063/1.3673475 VL - 83 IS - 1 PB - American Institute of Physics CY - Melville, NY ER - TY - JOUR A1 - Tan, Pi Lin A1 - Yeap, Guan Yeow A1 - Chow, Wen Shyang A1 - Schreiner, Rupert A1 - Cheong, Kuan Yew T1 - Effect of Thickness of Porphyrin on Electrical Properties of Organic Devices JF - Advanced Materials Research (AMR) N2 - The study on electrical properties for both 2,3,7,8,12,13,17,18-octaethyl-21,23H-porphine Cu (II) (Cu-porphyrin) and 2,3,7,8,12,13,17,18-octaethyl-21,23H-porphine (porphyrin) thin film, which were fabricated using spin coating method was conducted. Porphyrins were diluted with chloroform of various concentrations (0.05 mg/ml, 0.1 mg/ml, 0.5 mg/ml, 2.0 mg/ml and 3.0 mg/ml). The solution was spin coated on top of glass substrates. A layer of aluminum was evaporated on top of the organic thin film through thermal evaporation and shadow mask was placed on top of the organic thin film where two electrodes with a gap of 50 μm were formed. Surface morphology of the organic thin film was observed by scanning electron microscope (SEM) and profilometer. Different concentrations of organic solutions greatly affected the molecular packing and arrangement order of the organic thin film and thickness of the organic layer and eventually affected electrical properties of the devices. KW - Porphyrin KW - Electrical Properties KW - Spin Coating Y1 - 2014 U6 - https://doi.org/10.4028/www.scientific.net/AMR.1024.381 SN - 1662-8985 SN - 1022-6680 VL - 1024 SP - 381 EP - 384 PB - Trans Tech Publications Ltd. CY - Baech ER - TY - JOUR A1 - Dams, Florian A1 - Navitski, Aliaksandr A1 - Prommesberger, Christian A1 - Serbun, Pavel A1 - Langer, Christoph A1 - Müller, Günter A1 - Schreiner, Rupert T1 - Homogeneous Field Emission Cathodes With Precisely Adjustable Geometry Fabricated by Silicon Technology JF - IEEE Transactions on Electron Devices N2 - Silicon-based cathodes with precisely aligned field emitter arrays of sharp tips applicable for miniaturized electron sources were successfully fabricated and characterized. This was made possible by an improved fabrication process using wet thermal oxidation, wet etching, and reactive-ion etching steps with adjustable anisotropy. As substrate materials, both p-doped silicon and n-doped silicon were used. The cathode chips contain about 3 × 10 5 Si tips/cm 2 in a triangular array with tip heights of 2.5 μm, tip radii of less than 30 nm, and spacing of 20 μm. Well-aligned field emission (FE) and excellent homogeneity from all tips (i.e., 100% efficiency) and maximum stable currents of typically 0.1 μA (0.6 μA) for p (n)-type Si were reproducibly achieved. The current-voltage characteristics of the p-Si tips exhibit the expected saturation at around 10 nA with around ten times better current stability, whereas the n-Si tips show the usual Fowler-Nordheim behavior. Additional coating of the Si tips with 5-nm Cr and 10-nm Au layers resulted in improved stability and at least five times higher average FE current limits (about 3 μA) at about 30% higher operation voltage. KW - cathodes KW - electron field emission KW - elemental semiconductors KW - Field emission (FE) cathodes KW - field emitter array (FEA) KW - miniaturized electron sources KW - oxidation KW - silicon KW - silicon tips KW - sputter etching Y1 - 2012 U6 - https://doi.org/10.1109/TED.2012.2206598 SN - 0018-9383 SN - 1557-9646 VL - 59 IS - 10 SP - 2832 EP - 2837 PB - IEEE ER - TY - JOUR A1 - Ławrowski, Robert Damian A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Dams, Florian A1 - Schreiner, Rupert T1 - Improvement of Homogeneity and Aspect Ratio of Silicon Tips for Field Emission by Reactive-Ion Etching JF - Advances in Materials Science and Engineering. Special issue: Advances in Smart Materials and Applications N2 - The homogeneity of emitters is very important for the performance of field emission (FE) devices. Reactive-ion etching (RIE) and oxidation have significant influences on the geometry of silicon tips. The RIE influences mainly the anisotropy of the emitters. Pressure has a strong impact on the anisotropic factor. Reducing the pressure results in a higher anisotropy, but the etch rate is also lower. A longer time of etching compensates this effect. Furthermore an improvement of homogeneity was observed. The impact of uprating is quite low for the anisotropic factor, but significant for the homogeneity. At low power the height and undercut of the emitters are more constant over the whole wafer. The oxidation itself is very homogeneous and has no observable effect on further variation of the homogeneity. This modified fabrication process allows solving the problem of inhomogeneity of previous field emission arrays. Y1 - 2014 U6 - https://doi.org/10.1155/2014/948708 SN - 1687-8442 SN - 1687-8434 VL - 2014 SP - 1 EP - 6 PB - Hindawi ER -