TY - GEN A1 - Varlamova, Olga A1 - Hoefner, Kevin A1 - Ratzke, Markus A1 - Reif, Jürgen A1 - Sarker, Debasish T1 - Modification of surface properties of solids by femtosecond LIPSS writing: comparative studies on silicon and stainless steel T2 - Applied Physics A Y1 - 2017 U6 - https://doi.org/10.1007/s00339-017-1362-y SN - 0947-8396 SN - 1432-0630 VL - 123 IS - 12 ER - TY - GEN A1 - Czajkowski, Klaus A1 - Ratzke, Markus A1 - Varlamova, Olga A1 - Reif, Jürgen T1 - Femtosecond-laser-induced periodic surface structures on magnetic layer targets: The roles of femtosecond-laser interaction and of magnetization T2 - Applied Surface Science Y1 - 2017 U6 - https://doi.org/10.1016/j.apsusc.2017.03.148 SN - 0169-4332 VL - 417 SP - 84 EP - 87 ER - TY - GEN A1 - Oleynik, Paul A1 - Berkmann, Fritz A1 - Reiter, Sebastian A1 - Schlipf, Jon A1 - Ratzke, Markus A1 - Yamamoto, Yuji A1 - Fischer, Inga Anita T1 - Strong Optical Coupling of Lattice Resonances in a Top-down Fabricated Hybrid Metal–Dielectric Al/Si/Ge Metasurface T2 - Nano Letters N2 - Optical metasurfaces enable the manipulation of the light–matter interaction in ultrathin layers. Compared with their metal or dielectric counterparts, hybrid metasurfaces resulting from the combination of dielectric and metallic nanostructures can offer increased possibilities for interactions between modes present in the system. Here, we investigate the interaction between lattice resonances in a hybrid metal–dielectric metasurface obtained from a single-step nanofabrication process. Finite-difference time domain simulations show the avoided crossing of the modes appearing in the wavelength-dependent absorptance inside the Ge upon variations in a selected geometry parameter as evidence for strong optical coupling. We find good agreement between the measured and simulated absorptance and reflectance spectra. Our metasurface design can be easily incorporated into a top-down optoelectronic device fabrication process with possible applications ranging from on-chip spectroscopy to sensing. KW - metamaterials KW - semiconductors KW - hybridization KW - optoelectronics Y1 - 2024 U6 - https://doi.org/10.1021/acs.nanolett.3c05050 SN - 1530-6984 SN - 1530-6992 VL - 24 IS - 10 SP - 3142 EP - 3149 ER - TY - GEN A1 - Nitsch, Paul-G. A1 - Ratzke, Markus A1 - Pozarowska, Emilia A1 - Flege, Jan Ingo A1 - Alvarado Chavarin, Carlos A1 - Wenger, Christian A1 - Fischer, Inga Anita T1 - Deposition of reduced ceria thin films by reactive magnetron sputtering for the development of a resistive gas sensor T2 - Verhandlungen der DPG, Berlin 2024 N2 - The use of cerium oxide for hydrogen sensing is limited by the low electrical conductivity of layers deposited from a ceria target. To increase the electrical conductivity, partially reduced cerium oxide layers were obtained from a metallic cerium target by reactive magnetron sputtering. The proportions of the oxidation states Ce3+, present in reduced species, and Ce4+, present in fully oxidized species, were determined by ex-situ XPS. For electrical characterization, films were deposited on planarized tungsten finger electrodes. IV curves were measured over several days to investigate possible influences of oxygen and humidity on electrical conductivity. The morphological stability of the layers under ambient conditions was investigated by microscopical methods. The XPS results show a significant amount of Ce3+ in the layers. The electrical conductivity of as-grown samples is several orders of magnitude higher than that of samples grown from a ceria target. However, the conductivity decreases over time, indicating an oxidation of the layers. The surface morphology of the samples was found to be changing drastically within days, leading to partial delamination. KW - ceria KW - metalic cerium target KW - electrical conductivity KW - X-ray photoelectron spectroscopy (XPS) KW - oxidation states KW - morphology Y1 - 2024 UR - https://www.dpg-verhandlungen.de/year/2024/conference/berlin/part/ds/session/11/contribution/18 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Kosto, Yuliia A1 - Tschammer, Rudi A1 - Morales, Carlos A1 - Henkel, Karsten A1 - Flege, Jan Ingo A1 - Ratzke, Markus A1 - Fischer, Inga Anita A1 - Costina, Ioan A1 - Alvarado Chavarin, Carlos A1 - Wenger, Christian T1 - Rational design and development of room temperature hydrogen sensors compatible with CMOS technology: a necessary step for the coming renewable hydrogen economy T2 - Proceedings of iCampus Conference Cottbus 2024 N2 - The transition towards a new, renewable energy system based on green energy vectors, such as hydrogen, requires not only direct energy conversion and storage systems, but also the development of auxiliary components, such as highly sensitive hydrogen gas sensors integrated into mass devices that operate at ambient conditions. Despite the recent advances in nanostructured metal oxide thin films in terms of simple fabrication processes and compatibility with integrated circuits, high sensitivity, and short response/recovery times usually require the use of expensive noble metals or elevated tem-peratures (>250 ºC), which results in high power consumption and poor long-term stability. This article presents the first steps of the work on developing a novel resistive hydrogen gas sensor based on ultrathin cerium oxide films, compatible with complementary metal oxide semiconductor technology and capable of operating at room temperature. Here, we show a multidisciplinary bottom-up approach combining different work areas for the sensor development, such as sensor architecture, sensing mechanism and deposition strategy of the active layer, electrical contact design depending on the desired electrical output, and fast testing under controlled environments. KW - gas sensors KW - micro-structering KW - atomic layer deposition KW - sensor platform Y1 - 2024 SN - 978-3-910600-00-3 U6 - https://doi.org/10.5162/iCCC2024/P21 SP - 182 EP - 185 PB - AMA Service GmbH CY - Wunstorf ER - TY - GEN A1 - Eisenhauer, Nico A1 - Frank, Karin A1 - Weigelt, Alexandra A1 - Bartkowski, Bartosz A1 - Beugnon, Rémy A1 - Liebal, Katja A1 - Mahecha, Miguel A1 - Quaas, Martin A1 - Al‐Halbouni, Djamil A1 - Bastos, Ana A1 - Bohn, Friedrich J. A1 - Brito, Mariana Madruga de A1 - Denzler, Joachim A1 - Feilhauer, Hannes A1 - Fischer, Rico A1 - Fritsche, Immo A1 - Guimaraes‐Steinicke, Claudia A1 - Hänsel, Martin A1 - Haun, Daniel B. M. A1 - Herrmann, Hartmut A1 - Huth, Andreas A1 - Kalesse‐Los, Heike A1 - Koetter, Michael A1 - Kolleck, Nina A1 - Krause, Melanie A1 - Kretschmer, Marlene A1 - Leitão, Pedro J. A1 - Masson, Torsten A1 - Mora, Karin A1 - Müller, Birgit A1 - Peng, Jian A1 - Pöhlker, Mira L. A1 - Ratzke, Leonie A1 - Reichstein, Markus A1 - Richter, Solveig A1 - Rüger, Nadja A1 - Sánchez‐Parra, Beatriz A1 - Shadaydeh, Maha A1 - Sippel, Sebastian A1 - Tegen, Ina A1 - Thrän, Daniela A1 - Umlauft, Josefine A1 - Wendisch, Manfred A1 - Wolf, Kevin A1 - Wirth, Christian A1 - Zacher, Hannes A1 - Zaehle, Sönke A1 - Quaas, Johannes T1 - A belowground perspective on the nexus between biodiversity change, climate change, and human well‐being T2 - Journal of Sustainable Agriculture and Environment N2 - Soil is central to the complex interplay among biodiversity, climate, and society. This paper examines the interconnectedness of soil biodiversity, climate change, and societal impacts, emphasizing the urgent need for integrated solutions. Human‐induced biodiversity loss and climate change intensify environmental degradation, threatening human well‐being. Soils, rich in biodiversity and vital for ecosystem function regulation, are highly vulnerable to these pressures, affecting nutrient cycling, soil fertility, and resilience. Soil also crucially regulates climate, influencing energy, water cycles, and carbon storage. Yet, climate change poses significant challenges to soil health and carbon dynamics, amplifying global warming. Integrated approaches are essential, including sustainable land management, policy interventions, technological innovations, and societal engagement. Practices like agroforestry and organic farming improve soil health and mitigate climate impacts. Effective policies and governance are crucial for promoting sustainable practices and soil conservation. Recent technologies aid in monitoring soil biodiversity and implementing sustainable land management. Societal engagement, through education and collective action, is vital for environmental stewardship. By prioritizing interdisciplinary research and addressing key frontiers, scientists can advance understanding of the soil biodiversity–climate change–society nexus, informing strategies for environmental sustainability and social equity. Y1 - 2024 U6 - https://doi.org/10.1002/sae2.12108 SN - 2767-035X VL - 3 IS - 2 PB - Wiley ER - TY - GEN A1 - Reiter, Sebastian A1 - Ratzke, Markus A1 - Nitsch, Paul-Gregor A1 - Mai, Christian A1 - Spirito, Davide A1 - Corley-Wiciak, Agnieszka Anna A1 - Wenger, Christian A1 - Fischer, Inga A. T1 - Optical response of titanium nitride plasmonic nanohole arrays : impact of square and hexagonal array geometry, pitch, and nanohole diameter T2 - Plasmonics N2 - Plasmonic nanohole arrays (NHAs) exhibit extraordinary optical transmission (EOT) evoked by resonant excitation of surface plasmons at an excitation wavelength, which is highly sensitive to changes in refractive index in the surrounding dielectric. This can enable the use of plasmonic NHAs in on-chip refractive index sensors. Such sensors can be realized on the cost-effective silicon platform by the integration of a plasmonic NHA and a Ge photodetector, provided that complementary metal–oxide–semiconductor (CMOS)-compatible materials are used for their fabrication. Titanium nitride (TiN) as a biocompatible and CMOS-compatible plasmonic transition metal nitride is well-suited for integration on the silicon platform; however, the comparatively large losses within the material require geometry optimization strategies in order to improve the optical properties of TiN NHAs for sensing. In this work, we investigated different TiN NHA geometries both in experiment and simulation. We extensively characterized square and hexagonal arrays with varying pitches and nanohole diameters and provide a detailed comparison of their optical properties. We also discuss characterization results for surface refractive index changes imposed by depositing a thin Al2O3 layer on top of the NHAs. While we do not observe a clear advantage of hexagonal arrays compared to square arrays for sensing, our results highlight the importance of geometry optimization for TiN NHAs integrated with devices. KW - Plasmonic nanohole array KW - Titanium nitride KW - Hexagonal array KW - Square array KW - Nanohole diameters Y1 - 2025 UR - https://link.springer.com/article/10.1007/s11468-025-02934-4 U6 - https://doi.org/10.1007/s11468-025-02934-4 VL - 20 SP - 8825 EP - 8834 PB - Springer CY - New York, NY ER - TY - GEN A1 - Sengül, Akant A1 - Reiter, Sebastian A1 - Lotfi, Zahra A1 - Efremenko, Julia A1 - Laroussi, Arwa A1 - Corley-Wiciak, Agnieszka Anna A1 - Ratzke, Markus A1 - Mirsky, Vladimir M. A1 - Wenger, Christian A1 - Fischer, Inga Anita T1 - Titanium nitride plasmonic nanohole arrays with polymer coating : optical properties and their humidity-induced modifications T2 - Optical materials express N2 - The use of titanium nitride (TiN) for the fabrication of plasmonic structures such as nanohole arrays (NHAs) can enable their integration into optoelectronic devices on the silicon (Si) platform, for example, for the realization of on-chip chemical sensors and biosensors based on refractometric transduction. With a corresponding functionalization of the TiN nanohole arrays, these ultra-compact devices can be utilized in the development of various affinity sensors and sensor systems, such as cost-effective electronic noses for the early detection of gases in the food industry or agriculture. In this work, we focus on two types of coating for functionalization of TiN nanohole arrays: electrochemically synthesized poly-N-methylaniline and layer-by-layer deposited polyacrylic-acid/poly-allylamine (PAA/PAH). Our investigation comprises the experimental characterization of the optical properties of TiN nanhole arrays coated with polymer layers of different thicknesses as well as a comparison with simulation results. We demonstrate the potential of our setup sensing applications by measuring changes in optical properties of TiN nanohole arrays coated with PAA/PAH upon exposure to air of different humidity. Y1 - 2026 U6 - https://doi.org/10.1364/ome.578871 SN - 2159-3930 VL - 16 IS - 2 SP - 184 EP - 196 PB - Optica Publishing Group CY - Washington, DC ER -