TY - GEN A1 - Weißhaupt, David A1 - Sürgers, Christoph A1 - Bloos, Dominik A1 - Funk, Hannes Simon A1 - Oehme, Michael A1 - Fischer, Gerda A1 - Schubert, Markus Andreas A1 - Wenger, Christian A1 - van Slageren, Joris A1 - Fischer, Inga Anita A1 - Schulze, Jörg T1 - Lateral Mn5Ge3 spin-valve in contact with a high-mobility Ge two-dimensional hole gas T2 - Semiconductor Science and Technology N2 - Abstract Ge two-dimensional hole gases (2DHG) in strained modulation-doped quantum-wells represent a promising material platform for future spintronic applications due to their excellent spin transport properties and the theoretical possibility of efficient spin manipulation. Due to the continuous development of epitaxial growth recipes extreme high hole mobilities and low effective masses can be achieved, promising an efficient spin transport. Furthermore, the Ge 2DHG can be integrated in the well-established industrial complementary metal-oxide-semiconductor (CMOS) devices technology. However, efficient electrical spin injection into a Ge 2DHG—an essential prerequisite for the realization of spintronic devices—has not yet been demonstrated. In this work, we report the fabrication and low-temperature magnetoresistance (MR) measurements of a laterally structured Mn5Ge3/Ge 2DHG/ Mn5Ge3 device. The ferromagnetic Mn5Ge3 contacts are grown directly into the Ge quantum well by means of an interdiffusion process with a spacing of approximately 130 nm, forming a direct electrical contact between the ferromagnetic metal and the Ge 2DHG. Here, we report for the first time a clear MR signal for temperatures below 13 K possibly arising from successful spin injection into the high mobility Ge 2DHG. The results represent a step forward toward the realization of CMOS compatible spintronic devices based on a 2DHG. KW - two-dimensional hole gas Y1 - 2024 U6 - https://doi.org/10.1088/1361-6641/ad8d06 SN - 0268-1242 VL - 39 IS - 12 SP - 1 EP - 10 PB - IOP Publishing ER - TY - GEN A1 - Efremenko, Yulia A1 - Laroussi, Arwa A1 - Sengül, Akant A1 - Corley-Wiciak, Agnieszka Anna A1 - Fischer, Inga Anita A1 - Mirsky, Vladimir M. T1 - Deposition of Polymers on Titanium Nitride Electrodes T2 - Coatings N2 - The application of titanium nitride (TiN) as an electrode for electrochemical deposition or characterization requires the removal of an insulating layer from its surface. This process was studied and optimized, and the conditions for the complete removal of this layer through treatment with oxalic acid were formulated. The obtained TiN surfaces were used for the deposition of various conducting and non-conducting polymers. Two different approaches were applied: (i) in situ electrochemical synthesis of the main classes of conducting polymers, including polyaniline, polypyrrole, polythiophene, and selected derivatives thereof, and (ii) electrostatically driven layer-by-layer (LbL) deposition of multilayers of oppositely charged polyelectrolytes. The deposited polymers were characterized by electrochemical methods. The electrochemical properties of the deposited conducting polymers and their deposition on the TiN surface were comparable to those of the metallic electrodes. The films produced via LbL deposition exhibited a pronounced influence of the charge of the last deposited polymer on the redox reaction of ferri/ferrocyanide, validating the charge alteration with each successive polymer layer deposition. The studied deposition technologies can be used for the modification of TiN surfaces required in applications of this material in chemical sensors and other devices. Y1 - 2024 U6 - https://doi.org/10.3390/coatings14020215 SN - 2079-6412 VL - 14 IS - 2 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 - Becker, L. A1 - Storck, Peter A1 - Liu, Y. A1 - Schwalb, G. A1 - Schroeder, Thomas A1 - Fischer, Inga Anita A1 - Albrecht, M. T1 - Optimizing misfit dislocation glide kinetics for enhanced threading dislocation density reduction in Si1− xGex/Si (001) layers through dynamic growth rate control T2 - Journal of Applied Physics Y1 - 2024 U6 - https://doi.org/10.1063/5.0204318 SN - 0021-8979 SN - 1089-7550 VL - 135 IS - 20 SP - 10 ER - TY - GEN A1 - Berkmann, Fritz A1 - Povolni, Pavel A1 - Schwarz, Daniel A1 - Fischer, Inga Anita T1 - Influence of material and geometry parameters on resonance linewidths of plasmonic modes in gratings made from highly doped Ge1−xSnx T2 - Journal of Physics D: Applied Physics Y1 - 2024 U6 - https://doi.org/10.1088/1361-6463/ad67ea VL - 57 IS - 43 SP - 10 ER - TY - GEN A1 - Hayat, Ahsan A1 - Ratzke, Markus A1 - Alvarado Chavarin, Carlos A1 - Zöllner, Marvin Hartwig A1 - Corley-Wiciak, Agnieszka Anna A1 - Schubert, Markus Andreas A1 - Wenger, Christian A1 - Fischer, Inga Anita T1 - Structural and morphological properties of CeO2 films deposited by radio frequency magnetron sputtering for back-end-of-line integration T2 - Thin Solid Films Y1 - 2024 U6 - https://doi.org/10.1016/j.tsf.2024.140547 SN - 0040-6090 VL - 807 ER - TY - GEN A1 - Reiter, Sebastian A1 - Sengül, Akant A1 - Mai, Christian A1 - Spirito, Davide A1 - Wenger, Christian A1 - Fischer, Inga Anita T1 - On-chip refractive index sensors based on plasmonic TiN Nanohole Arrays T2 - 2024 IEEE Silicon Photonics Conference (SiPhotonics) Y1 - 2024 SN - 979-8-3503-9404-7 SN - 979-8-3503-9405-4 U6 - https://doi.org/10.1109/SiPhotonics60897.2024.10544048 SN - 1949-209X ER - TY - GEN A1 - Fischer, Inga Anita T1 - CMOS-compatible metasurfaces integrated with optoelectronic devices: tuning light-matter interaction at the nanoscale T2 - Technical Digest Series (Optica Publishing Group, 2024), paper SM2L.7 Y1 - 2024 SN - 978-1-957171-39-5 U6 - https://doi.org/10.1364/CLEO_SI.2024.SM2L.7 ER - TY - GEN A1 - Jose, Josmy A1 - Mai, Christian A1 - Wenger, Christian A1 - Fischer, Inga Anita T1 - Integration concept of plasmonic TiN nanohole arrays in a 200 mm BiCMOS Si technology for refractive index sensor applications T2 - iCCC2024 - iCampµs Cottbus Conference Y1 - 2024 U6 - https://doi.org/10.5162/iCCC2024/7.2 SP - 96 EP - 99 ER - 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 -