TY - GEN A1 - Mai, Christian A1 - Peczek, Anna A1 - Kroh, Aleksandra A1 - Jose, Josmy A1 - Reiter, Sebastian A1 - Wenger, Christian A1 - Fischer, Inga Anita T1 - Towards a CMOS compatible refractive index sensor: cointegration of TiN nanohole arrays and Ge photodetectors in a 200 mm wafer silicon technology T2 - Optics Express N2 - In this work, we present the monolithic integration of a TiN nanohole array and a Ge photodetector towards a CMOS compatible fabrication of a refractive index sensor in a 200 mm wafer silicon technology. We developed a technology process that enables fabrication with high yields of around 90%. Ge photodetectors with a Ge layer thickness of 450 nm and an area of 1600 µm2 (40 µm x 40 µm) show dark current densities of around 129 mA/cm2 and responsivities of 0.114 A/W measured by top illumination (TE polarization; λ = 1310 nm; angle of incidence = 14 °) at a reverse bias of 1 V. Nanohole arrays were structured in a 150 nm thick TiN layer. They were integrated into the back end of line and placed spatially close to the Ge photodetectors. After the metallization, passivation, and pad opening, the nanohole arrays were released with the help of an amorphous silicon stop layer. A significant impact of the TiN nanohole arrays on the optical behavior of the photodetector could be proven on the wafer level. Photocurrent measurements by top illumination confirm a strong dependence of optical properties on the polarization of the incident light and the nanohole array design. We demonstrate very stable photocurrents on the wafer level with a standard deviation of σ < 6%. KW - plasmonics KW - sensor KW - nano hole array Y1 - 2024 U6 - https://doi.org/10.1364/OE.530081 SN - 1094-4087 VL - 32 IS - 17 SP - 29099 EP - 29111 PB - Optica Publishing Group ER - TY - GEN A1 - Dersch, Nadine A1 - Roemer, Christian A1 - Perez, Eduardo A1 - Wenger, Christian A1 - Schwarz, Mike A1 - Iñíguez, Benjamín A1 - Kloes, Alexander T1 - Fast circuit simulation of memristive crossbar arrays with bimodal stochastic synaptic weights T2 - 2024 IEEE Latin American Electron Devices Conference (LAEDC) N2 - This paper presents an approach for highly efficient circuit simulation of hardware-based artificial neural networks by using memristive crossbar array architectures. There are already possibilities to test neural networks with stochastic weights via simulations like the macro model NeuroSim. However, the noise-based variability approach offers more realistic setting options including elements of a classical circuit simulation for more precise analysis of neural networks. With this approach, statistical parameter fluctuations can be simulated based on different distribution functions of devices. In Cadence Virtuoso, a simulation of a crossbar array with 10 synaptic weights following a bimodal distribution, the new approach shows a 1,000x speedup compared to a Monte Carlo simulation. Initial tests of a memristive crossbar array with over 15,000 stochastic weights to classify the MNIST dataset show that the new approach can be used to test the functionality of hardware-based neural networks. KW - RRAM Y1 - 2024 SN - 979-8-3503-6130-8 U6 - https://doi.org/10.1109/LAEDC61552.2024.10555829 SN - 979-8-3503-6129-2 SN - 2835-3471 SP - 1 EP - 4 PB - IEEE ER - TY - GEN A1 - Reiter, Sebastian A1 - Han, Weijia A1 - Mai, Christian A1 - Spirito, Davide A1 - Jose, Josmy A1 - Zöllner, Marvin Hartwig A1 - Fursenko, Oksana A1 - Schubert, Markus Andreas A1 - Stemmler, Ivo A1 - Wenger, Christian A1 - Fischer, Inga Anita T1 - Titanium Nitride Plasmonic Nanohole Arrays for CMOS-compatible integrated refractive index sensing: influence of layer thickness on optical properties T2 - Plasmonics Y1 - 2023 U6 - https://doi.org/10.1007/s11468-023-01810-3 SN - 1557-1963 SP - 1 EP - 13 ER - TY - GEN A1 - Han, Weijia A1 - Reiter, Sebastian A1 - Schlipf, Jon A1 - Mai, Christian A1 - Spirito, Davide A1 - Jose, Josmy A1 - Wenger, Christian A1 - Fischer, Inga Anita T1 - Strongly enhanced sensitivities of CMOS compatible plasmonic titanium nitride nanohole arrays for refractive index sensing under oblique incidence T2 - Optics Express N2 - Titanium nitride (TiN) is a complementary metal-oxide-semiconductor (CMOS) compatible material with large potential for the fabrication of plasmonic structures suited for device integration. However, the comparatively large optical losses can be detrimental for application. This work reports a CMOS compatible TiN nanohole array (NHA) on top of a multilayer stack for potential use in integrated refractive index sensing with high sensitivities at wavelengths between 800 and 1500 nm. The stack, consisting of the TiN NHA on a silicon dioxide (SiO2) layer with Si as substrate (TiN NHA/SiO2/Si), is prepared using an industrial CMOS compatible process. The TiN NHA/SiO2/Si shows Fano resonances in reflectance spectra under oblique excitation, which are well reproduced by simulation using both finite difference time domain (FDTD) and rigorous coupled-wave analysis (RCWA) methods. The sensitivities derived from spectroscopic characterizations increase with the increasing incident angle and match well with the simulated sensitivities. Our systematic simulation-based investigation of the sensitivity of the TiN NHA/SiO2/Si stack under varied conditions reveals that very large sensitivities up to 2305 nm per refractive index unit (nm RIU−1) are predicted when the refractive index of superstrate is similar to that of the SiO2 layer. We analyze in detail how the interplay between plasmonic and photonic resonances such as surface plasmon polaritons (SPPs), localized surface plasmon resonances (LSPRs), Rayleigh Anomalies (RAs), and photonic microcavity modes (Fabry-Pérot resonances) contributes to this result. This work not only reveals the tunability of TiN nanostructures for plasmonic applications but also paves the way to explore efficient devices for sensing in broad conditions. KW - TiN KW - Plasmonics Y1 - 2023 U6 - https://doi.org/10.1364/OE.481993 SN - 1094-4087 VL - 31 IS - 11 SP - 17389 EP - 17407 ER - TY - GEN A1 - Zöllner, Christian A1 - Adriano, Christian M. A1 - Wietheger, Simon A1 - Lambers, Leen A1 - Giese, Holger ED - Kühn, Thomas ED - Sousa, Vasco T1 - Tool support for the teaching of state-based behavior modeling T2 - MODELS '22: Proceedings of the 25th International Conference on Model Driven Engineering Languages and Systems: Companion Proceedings N2 - Modeling tools are commonly adopted in classrooms. However, complex state-based behavioral models still pose a challenge for students to understand and validate, mostly because of the intricate semantics of these models. We investigated this challenge and developed dedicated tool support in the form of a validation framework based on the YAKINDU Statechart Tools. Our validation framework simulates environments that interact with the code generated from statecharts as a means to animate various open-ended scenarios and predefined test cases that challenge the students' models. This enables short and user-friendly feedback cycles, which lowers the barrier for students to learn state-based behavioral models. We designed the validation framework to be extensible and made it available as an open source project together with two example environments and complete teaching materials. We report on our experiences in two undergraduate modeling courses (approx. 100 students each). Our results are promising in the sense that we detected positive effects of tool adoption and a surprising lack thereof, which we discuss w.r.t. lessons learned and future work. KW - modeling KW - education KW - statecharts KW - simulation KW - validation framework Y1 - 2022 SN - 978-1-4503-9467-3 U6 - https://doi.org/10.1145/3550356.3556501 SP - 87 EP - 94 PB - Association for Computing Machinery CY - New York, NY, United States ER - TY - BOOK A1 - Steffens, Oliver A1 - Dawoud, Belal A1 - Rechenauer, Christian A1 - Mühlberger, Thomas A1 - Trauner, Matthias A1 - Saller, Tobias A1 - Riederer, Michael A1 - Haug, Sonja A1 - Vetter, Miriam A1 - Cerullo, Laura A1 - Weber, Karsten A1 - Draeger, Susan A1 - Kominis, Lena A1 - Steininger, Peter A1 - Malz, Sebastian A1 - Gerdes, Thorsten A1 - Melzl, Johannes A1 - Haas, Katharina A1 - Helling, Dominik A1 - Zielbauer, Lukas A1 - Stelzl, André A1 - Andratschke, Christin A1 - Grießhammer, Peter A1 - Giebisch, Matthias A1 - Preis, Michael A1 - Michlbauer, David A1 - Walbrunn, Johannes A1 - Nagel, Klaus A1 - Lang, Christian A1 - Schnabl, Andreas A1 - Toutouly, Lovis A1 - Rückerl, Alexander ED - Steffens, Oliver T1 - MAGGIE - Energetische Modernisierung des genossenschaftlichen Wohnquartiers Margaretenau in Regensburg : Musterlösungen für solaroptimiertes Wohnen mit innovativen solaraktiven Baustoffen und einem KI-gestützten Energiemanagement für eine netzdienliche, emissionsarme Strom- und Wärmelogistik; Ergebnisbericht N2 - Das Projekt MAGGIE ist ein vom Bundesministerium für Wirtschaft und Klimaschutz (BMWK) gefördertes Projekt innerhalb der Förderinitiative „Solares Bauen/Energieeziente Stadt“ im Rahmen des 6. Energieforschungsprogramms. Im Projekt MAGGIE sollten beispielhaft für das genossenschaftliche historische Stadtquartier „Margaretenau“ in Regensburg Musterlösungen für energieoptimiertes Wohnen mit innovativen Wandauauten aus solaraktiven Baustoen und einer vorhersagebasierten Versorgungstechnologie entwickelt werden. Für ein bestehendes Wohngebäude als Demonstrationsund Versuchsobjekt wurde beispielhaft ein neuartiges, besonders ezientes Hybridsystem aus Wärmepumpentechnologie und Kraft-Wärme-Kopplung (Blockheizkraftwerk) konzipiert und umgesetzt. Für die denkmalgerechte Modernisierung historischer Fassaden wurde ein solaraktives und solaradaptives Außenputzsystem entwickelt und getestet. Der erhöhte Ausnutzungsgrad solarer Gewinne in Verbindung mit einer verbesserten thermischen Behaglichkeit im Gebäudeinnerendurch innovative Innenputz-/Innenfarbsysteme kann maßgeblich zur Einsparung von Heizwärme beitragen. Dazu wurden mit Blick auf die bauphysikalischen und wärmetechnischen Eigenschaften Versuche an einem eigens aufgebauten Wandprüfstand durchgeführt, ergänzt durch bauphysikalische Modellsimulationen. Die Ergebnisse sind vielversprechend, auch wenn eine serientaugliche Lösung für den Einsatz am Gebäude im Rahmen des Projektes nicht entstehen konnte. Das wichtigste Ziel des Projektes war es, ein hochezientes, skalierbares Versorgungssystem durch die Kombination von Kraft-Wärme-Kopplung (Blockheizkraftwerk, BHKW) mit einer Pvunterstützten Wärmepumpen-Technologie zu entwickeln und im Detail zu modellieren, in Verbindung mit einer innovativenWärmelogistik zur Reduktion der Verteilungsverluste für dieWarm-wasserversorgung. Das Systemsollte neben einem hohen Eigenstrom-Nutzungsanteil auch netzdienliche Schwarmfunktionalität aufweisen. Die Skalierbarkeit des vernetzten Systems („Mitwachsen“) erlaubt eine abschnittsweise Modernisierung des gesamten Ensembles über mehrere Jahre, was für die Finanzierbarkeit und praktische Umsetzung erhebliche Bedeutung hat. Durch die hohe Energieezienz wird die Warmmiete für die Bewohner der genossenschaftlichen Siedlung durch die Modernisierungsmaßnahmen nicht erhöht, so dass auch nach der Modernisierung ein bezahlbares Wohnen sichergestellt wird. Die Auslegung des Systems erfolgte durch ein neu entwickeltes, generisch einsetzbares Planungs-, Optimierungs- und Steuerungstool, das auch die Regelung im Betrieb übernimmt. Die in Echtzeit laufende Nachoptimierung des Systems während des Betriebs greift auf reale Monitoringdaten zu. Die Einbindung von Nutzerbedarfsprolen, Strombörse und Wetterdaten in die Steuerung ist vorbereitet und gestattet einen dynamischen und perspektivischen Anlagenbetrieb zur Maximierung der Solar- und Umweltwärme-Anteile der Energieversorgung. Mithilfe einer intensiven Nutzerinformation in einem partizipativen Planungsprozess wurde die Akzeptanz der experimentellen Maßnahmen sichergestellt. Durch oene Kommunikation der Zielsetzungen und Lösungsansätze für eine klimafreundliche, kostenbewusste Restaurierung des Wohnungsbestands und die aktive Einbindung der Bewohner fand das Projekt das Interesse und die Unterstützung der Menschen, auch in der schwierigen Phase der Umsetzung baulicher Maßnahmen in einem zwangsläug in Abschnitten vorübergehend entmieteten Gebäude. KW - Klimaschutz KW - Bauwende KW - Klimaanpassung KW - Energieeffiziente Sanierung KW - klimagerechte Sanierung KW - Partizipation Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-59011 N1 - Gefördert durch einen Beschluss des Bundestages durch das Bundesministerium für Wirtschaft und Klimaschutz (BMWK); Projektlaufzeit Oktober 2017 bis Juni 2022; Förderkennzeichen 03SBE0007A–E CY - Regensburg ER - TY - GEN A1 - Dersch, Nadine A1 - Perez-Bosch Quesada, Emilio A1 - Pérez, Eduardo A1 - Wenger, Christian A1 - Roemer, Christian A1 - Schwarz, Mike A1 - Kloes, Alexander T1 - Efficient circuit simulation of a memristive crossbar array with synaptic weight variability T2 - Solid State Electronics N2 - In this paper, we present a method for highly-efficient circuit simulation of a hardware-based artificial neural network realized in a memristive crossbar array. The statistical variability of the devices is considered by a noise-based simulation technique. For the simulation of a crossbar array with 8 synaptic weights in Cadence Virtuoso the new approach shows a more than 200x speed improvement compared to a Monte Carlo approach, yielding the same results. In addition, first results of an ANN with more than 15,000 memristive devices classifying test data of the MNIST dataset are shown, for which the speed improvement is expected to be several orders of magnitude. Furthermore, the influence on the classification of parasitic resistances of the connection lines in the crossbar is shown. KW - RRAM KW - Neural network Y1 - 2023 U6 - https://doi.org/10.1016/j.sse.2023.108760 SN - 0038-1101 VL - 209 ER - TY - GEN A1 - Klein, Rupert A1 - Nadolski, Maikel A1 - Zenker, Christian A1 - Oevermann, Michael A1 - Paschereit, Christian Oliver T1 - Pressure gain combustion for gas turbines : analysis of a fully coupled engine model T2 - Journal of Engineering for Gas Turbines and Power N2 - The “Shockless Explosion Combustion” (SEC) concept for gas turbine combustors, introduced in 2014, approximates constant volume combustion (CVC) by harnessing acoustic confinement of auto-igniting gas packets. The resulting pressure waves simultaneously transmit combustion energy to a turbine plenum and facilitate the combustor's recharging against an average pressure gain. Challenges in actualizing an SEC-driven gas turbine include (i) the creation of charge stratifications for nearly homogeneous auto-ignition, (ii) protecting the turbocomponents from combustion-induced pressure fluctuations, (iii) providing evidence that efficiency gains comparable to those of CVC over deflagrative combustion can be realized, and (iv) designing an effective one-way intake valve. This work addresses challenges (i)–(iii) utilizing computational engine models incorporating a quasi-one-dimensional combustor, zero- and two-dimensional (2D) compressor and turbine plena, and quasi-stationary turbocomponents. Two SEC operational modes are identified which fire at roughly one and two times the combustors' acoustic frequencies. Results for SEC-driven gas turbines with compressor pressure ratios of 6:1 and 20:1 reveal 1.5-fold mean pressure gains across the combustors. Assuming ideally efficient compressors and turbines, efficiency gains over engines with deflagration-based combustors of 30% and 18% are realized, respectively. With absolute values of 52% and 66%, the obtained efficiencies are close to the theoretical Humphrey cycle efficiencies of 54% and 65% for the mentioned precompression ratios. Detailed thermodynamic cycle analyses for individual gas parcels suggest that there is room for further efficiency gains through optimized plenum and combustor designs. Y1 - 2024 U6 - https://doi.org/10.1115/1.4066348 SN - 0742-4795 VL - 147 IS - 2 PB - ASME International ER - TY - GEN A1 - Stich, Timo A1 - Linz, Christian A1 - Wallraven, Christian A1 - Cunningham, Douglas William A1 - Magnor, Marcus T1 - Perception-motivated interpolation of image sequences T2 - ACM Transactions and Applied Perception Y1 - 2011 SN - 1544-3965 VL - 8 IS - 2 SP - 1 EP - 25 ER - TY - CHAP A1 - Stich, Timo A1 - Linz, Christian A1 - Wallraven, Christian A1 - Cunningham, Douglas William A1 - Magnor, Marcus T1 - Perception-motivated Interpolation of Image Sequences T2 - Proceedings APGV 2008, Symposium on Applied Perception in Graphics and Visualization Los Angeles, California, August 9-10, 2008 Y1 - 2008 SN - 978-1-595-93981-4 SP - 97 EP - 106 PB - The Association for Computing Machinery CY - New York, NY ER -