@misc{WeisshauptFunkSuergersetal., author = {Weißhaupt, David and Funk, Hannes S. and S{\"u}rgers, Christoph and Fischer, Gerda and Oehme, Michael and Schwarz, Daniel and Fischer, Inga Anita and Slageren, Joris van and Schulze, J{\"o}rg}, title = {Formation of Mn5Ge3 on a Recess-Etched Ge (111) Quantum-Well Structure for Semiconductor Spintronics}, series = {44th International Convention on Information, Communication and Electronic Technology, MIPRO 2021, Opatija, Croatia, September 27 - Oct. 1, 2021}, journal = {44th International Convention on Information, Communication and Electronic Technology, MIPRO 2021, Opatija, Croatia, September 27 - Oct. 1, 2021}, publisher = {Piscataway}, address = {IEEE}, isbn = {978-1-6654-4761-4}, issn = {978-953-233-101-1}, doi = {10.23919/MIPRO52101.2021.9596924.}, pages = {45 -- 49}, language = {en} } @misc{WeisshauptSuergersBloosetal., author = {Weißhaupt, David and S{\"u}rgers, Christoph and Bloos, Dominik and Funk, Hannes Simon and Oehme, Michael and Fischer, Gerda and Schubert, Markus Andreas and Wenger, Christian and van Slageren, Joris and Fischer, Inga Anita and Schulze, J{\"o}rg}, title = {Lateral Mn5Ge3 spin-valve in contact with a high-mobility Ge two-dimensional hole gas}, series = {Semiconductor Science and Technology}, volume = {39}, journal = {Semiconductor Science and Technology}, number = {12}, publisher = {IOP Publishing}, issn = {0268-1242}, doi = {10.1088/1361-6641/ad8d06}, pages = {1 -- 10}, abstract = {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.}, language = {en} } @misc{SchwartzOehmeKosteckietal., author = {Schwartz, Bernhard and Oehme, Michael and Kostecki, Konrad and Widmann, Daniel and Gollhofer, Martin and K{\"o}rner, Roman and Bechler, Stefan and Fischer, Inga Anita and Wendav, Torsten and Kasper, Erich and Schulze, J{\"o}rg and Kittler, Martin}, title = {Electroluminescence of GeSn/Ge MQW LEDs on Si substrate}, series = {Optics Letters}, volume = {40}, journal = {Optics Letters}, number = {13}, doi = {10.1364/OL40.003209}, pages = {3209 -- 3212}, language = {en} } @misc{WendavFischerVirgilioetal., author = {Wendav, Torsten and Fischer, Inga Anita and Virgilio, Michele and Capellini, Giovanni and Oliveira, F. and Cerqueira, M. F. and Benedetti, Alessandro and Chiussi, Stefano and Zaumseil, Peter and Schwartz, Bernhard and Busch, Kurt and Schulze, J.}, title = {Photoluminescence from ultrathin Ge-rich multiple quantum wells observed up to room temperature: Experiments and modeling}, series = {Physical Review B 94}, volume = {94}, journal = {Physical Review B 94}, number = {24}, doi = {10.1103/PhysRevB.94.245304}, pages = {245304}, language = {en} } @misc{KoernerSchwarzFischeretal., author = {K{\"o}rner, Roman and Schwarz, Daniel and Fischer, Inga Anita and Augel, Lion and Bechler, Stefan and H{\"a}nel, Linda A. and Kern, Michael and Oehme, Michael and Rolseth, Erlend Granbo and Schwartz, Bernhard and Weißhaupt, David and Zhang, Wogong and Schulze, J{\"o}rg}, title = {The Zener-Emitter: A Novel Superluminescent Ge Optical Waveguide-Amplifier with 4.7 dB Gain at 92 mA Based on Free-Carrier Modulation by Drect Zener Tunneling Monolithically Integrated on Si}, series = {2016 IEEE International Electronic Devices Meeting (IEDM), 3-7 Dec. 2016}, journal = {2016 IEEE International Electronic Devices Meeting (IEDM), 3-7 Dec. 2016}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-5090-3901-2}, pages = {22.5.1 -- 22.5.4}, language = {en} } @misc{SchlipfMartinStchakovskyetal., author = {Schlipf, Jon and Martin, Elena and Stchakovsky, Michel and Benedetti, Alessandro and Fischer, Inga Anita and Schulze, J{\"o}rg and Chiussi, Stefano}, title = {Ellipsometric analysis of concentration gradients induced in semiconductor crystals by pulsed laser induced epitaxy}, series = {Journal of Vacuum Science \& Technology B}, volume = {37}, journal = {Journal of Vacuum Science \& Technology B}, number = {6}, issn = {2166-2754}, doi = {10.1116/1.5122777}, language = {en} } @misc{FunkKernWeisshauptetal., author = {Funk, Hannes S. and Kern, Michael and Weisshaupt, David and S{\"u}rgers, Christoph and Fischer, Inga Anita and Oehme, Michael and Slageren, Joris van and Schulze, J{\"o}rg}, title = {Magnetic Characterization of a Mn Based Ferromagnet on SixGe(1-x-y)Sny with High Sn Content}, series = {ECS Transactions}, volume = {93}, journal = {ECS Transactions}, number = {1}, issn = {1938-5862}, doi = {10.1149/09301.0101ecst}, pages = {101 -- 104}, language = {en} } @misc{FischerAugelBerkmannetal., author = {Fischer, Inga Anita and Augel, Lion and Berkmann, Fritz and Kawaguchi, Yuma and Schlipf, Jon and Schulze, J{\"o}rg}, title = {Plasmonics-Integrated Ge PIN-Photodetectors}, series = {ECS Transactions}, volume = {93}, journal = {ECS Transactions}, number = {1}, issn = {1938-5862}, doi = {10.1149/09301.0041ecst}, pages = {41 -- 44}, language = {en} } @misc{FischerClausenSchwarzetal., author = {Fischer, Inga Anita and Clausen, Caterina J. and Schwarz, Daniel and Zaumseil, Peter and Capellini, Giovanni and Virgilio, Michele and Da Silva Figueira, Maria Cecilia and Birner, Stefan and Koelling, Sebastian and Koenraad, Paul M. and Huang, Michael R. S. and Koch, Christoph T. and Wendav, Torsten and Busch, Kurt and Schulze, J{\"o}rg}, title = {Composition analysis and transition energies of ultrathin Sn-rich GeSn quantum wells}, series = {Physical Review Materials}, volume = {4}, journal = {Physical Review Materials}, number = {2}, issn = {2475-9953}, doi = {10.1103/PhysRevMaterials.4.024601}, pages = {10}, language = {en} } @misc{SchlykowManganelliRoemeretal., author = {Schlykow, Viktoria and Manganelli, Constanza Lucia and R{\"o}mer, Friedhard and Clausen, Caterina J. and Augel, Lion and Schulze, J{\"o}rg and Katzer, Jens and Schubert, Michael Andreas and Witzigmann, Bernd and Schroeder, Thomas and Capellini, Giovanni and Fischer, Inga Anita}, title = {Ge(Sn) nano-island/Si heterostructure photodetectors with plasmonic antennas}, series = {Nanotechnology}, volume = {31}, journal = {Nanotechnology}, number = {34}, issn = {1361-6528}, doi = {10.1088/1361-6528/ab91ef}, pages = {11}, language = {en} } @misc{AugelFischerGollhoferetal., author = {Augel, Lion and Fischer, Inga Anita and Gollhofer, Martin and Oehme, Michael and Schulze, J{\"o}rg}, title = {Comparing Fourier transform infrared spectroscopy results with photocurrent measurements for Ge-on-Si PIN photodetectors with and without Al nanoantennas}, series = {Journal of Applied Physics}, volume = {128}, journal = {Journal of Applied Physics}, number = {1}, issn = {1089-7550}, doi = {10.1063/5.0012279}, pages = {013105-1 -- 013105-8}, language = {en} } @misc{WeisshauptFunkKernetal., author = {Weißhaupt, David and Funk, Hannes S. and Kern, Michal and Dettling, Marco M. and Schwarz, Daniel and Oehme, Michael and S{\"u}rgers, Christoph and Slageren, Joris van and Fischer, Inga Anita and Schulze, J{\"o}rg}, title = {Weak localization and weak antilocalization in doped Ge1-ySny layers with up to 8\% Sn}, series = {Journal of Physics: Condensed Matter}, volume = {33}, journal = {Journal of Physics: Condensed Matter}, number = {8}, issn = {1361-648X}, doi = {10.1088/1361-648X/abcb68}, pages = {8}, language = {en} } @misc{SchlipfTetznerSpiritoetal., author = {Schlipf, Jon and Tetzner, Henriette and Spirito, Davide and Manganelli, Constanza Lucia and Capellini, Giovanni and Huang, Michael R. S. and Koch, Christoph T. and Clausen, Caterina J. and Elsayed, Ahmed and Schulze, J{\"o}rg and Fischer, Inga Anita}, title = {Raman shifts in MBE-grown SixGe1 - x - ySny alloys with large Si content}, series = {Journal of Raman Spectroscopy}, journal = {Journal of Raman Spectroscopy}, issn = {1097-4555}, doi = {10.1002/jrs.6098}, pages = {9}, language = {en} } @misc{AugelSchlipfBullertetal., author = {Augel, Lion and Schlipf, Jon and Bullert, Sergej and B{\"u}rzele, Sebastian and Schulze, J{\"o}rg and Fischer, Inga Anita}, title = {Photonic-plasmonic mode coupling in nanopillar Ge-on-Si PIN photodiodes}, series = {Scientific Reports}, journal = {Scientific Reports}, number = {11}, issn = {2045-2322}, doi = {10.1038/s41598-021-85012-z}, pages = {9}, abstract = {Incorporating group IV photonic nanostructures within active top-illuminated photonic devices often requires light-transmissive contact schemes. In this context, plasmonic nanoapertures in metallic films can not only be realized using CMOS compatible metals and processes, they can also serve to influence the wavelength-dependent device responsivities. Here, we investigate crescent-shaped nanoapertures in close proximity to Ge-on-Si PIN nanopillar photodetectors both in simulation and experiment. In our geometries, the absorption within the devices is mainly shaped by the absorption characteristics of the vertical semiconductor nanopillar structures (leaky waveguide modes). The plasmonic resonances can be used to influence how incident light couples into the leaky modes within the nanopillars. Our results can serve as a starting point to selectively tune our device geometries for applications in spectroscopy or refractive index sensing.}, language = {en} } @misc{SchlipfFischer, author = {Schlipf, Jon and Fischer, Inga Anita}, title = {Rigorous coupled-wave analysis of a multi-layered plasmonic integrated refractive index sensor}, series = {Optics Express}, volume = {Vol. 29}, journal = {Optics Express}, number = {22}, issn = {1094-4087}, doi = {10.1364/OE.438585}, pages = {36201 -- 36210}, language = {en} } @misc{TetznerFischerSkibitzkietal., author = {Tetzner, Henriette and Fischer, Inga Anita and Skibitzki, Oliver and Mirza, M. M. and Manganelli, Constanza Lucia and Luongo, G. and Spirito, Davide and Douglas, J. P. and De Seta, Monica and Capellini, Giovanni}, title = {Current leakage mechanisms related to threading dislocations in Ge-rich SiGe heterostructures grown on Si(001)}, series = {Applied Physics Letters}, volume = {119}, journal = {Applied Physics Letters}, number = {15}, issn = {1077-3118}, doi = {10.1063/5.0064477}, language = {en} } @misc{BergmannAyasseSchlipfetal., author = {Bergmann, Fritz and Ayasse, Markus and Schlipf, Jon and M{\"o}rz, Florian and Weißhaupt, David and Oehme, Michael and Prucnal, Slawomir and Kawaguchi, Yuma and Schwarz, Daniel and Fischer, Inga Anita and Schulze, J{\"o}rg}, title = {Plasmonic gratings from highly doped Ge1-ySny films on Si}, series = {Journal of Physics D: Applied Physics}, volume = {54}, journal = {Journal of Physics D: Applied Physics}, number = {44}, issn = {1361-6463}, language = {en} } @misc{BerkmannAyasseMoerzetal., author = {Berkmann, Fritz and Ayasse, Markus and M{\"o}rz, Florian and Fischer, Inga Anita and Schulze, J{\"o}rg}, title = {Titanium and Nickel as alternative materials for mid Infrared Plasmonic}, series = {44th International Convention on Information, Communication and Electronic Technology, MIPRO 2021, Opatija, Croatia, September 27 - Oct. 1, 2021}, journal = {44th International Convention on Information, Communication and Electronic Technology, MIPRO 2021, Opatija, Croatia, September 27 - Oct. 1, 2021}, publisher = {Piscataway}, address = {IEEE}, isbn = {978-953-233-101-1}, doi = {10.23919/MIPRO52101.2021.9597155}, pages = {36 -- 39}, language = {en} } @misc{FunkKernWeisshauptetal., author = {Funk, Hannes S. and Kern, Michael and Weißhaupt, David and S{\"u}rgers, Christoph and Fischer, Inga Anita and Oehme, Michael and Slageren, Joris van and Schulze, J{\"o}rg}, title = {Composition and magnetic properties of thin films grown by interdiffusion of Mn and Sn-Rich, Ge lattice matched SixGe1-x-ySny layers}, series = {Journal of Magnetism and Magnetic Materials}, volume = {546}, journal = {Journal of Magnetism and Magnetic Materials}, issn = {0304-8853}, doi = {10.1016/j.jmmm.2021.168731.}, pages = {8}, language = {en} } @misc{ElogailBerkmannClausenetal., author = {Elogail, Yasmine and Berkmann, Fritz and Clausen, Caterina J. and Fischer, Inga Anita and H{\"a}nel, Linda A. and Schwarz, Daniel and Schulze, J{\"o}rg}, title = {Investigation of Ge-Based P-Channel Planar-Doped Barrier FETs integrated on Si}, series = {Microelectronics Journal}, volume = {123}, journal = {Microelectronics Journal}, issn = {1879-2391}, doi = {10.1016/j.mejo.2022.105404}, pages = {11}, language = {en} } @misc{XieBirowskaFunketal., author = {Xie, Yufang and Birowska, Magdalena and Funk, Hannes S. and Fischer, Inga Anita and Schwarz, Daniel and Schulze, J{\"o}rg and Zeng, Yu-Jia and Helm, Manfred and Zhou, Shengqiang and Prucnal, Slawomir}, title = {Tuning of Curie temperature in Mn5Ge3 films}, series = {Journal of Applied Physics}, volume = {131}, journal = {Journal of Applied Physics}, issn = {1089-7550}, doi = {10.1063/5.0066717}, pages = {105102-1 -- 105102-8}, language = {en} } @misc{BerkmannAugelHacketal., author = {Berkmann, Fritz and Augel, Lion and Hack, Michael and Kawaguchi, Yuma and Weißhaupt, David and Fischer, Inga Anita and Schulze, J{\"o}rg}, title = {Optimization of fully integrated Al nanohole array-based refractive index sensors for use with a LED light source Fritz Berkmann}, series = {IEEE Photonics Journal}, volume = {14}, journal = {IEEE Photonics Journal}, number = {3}, issn = {1943-0655}, doi = {10.1109/JPHOT.2022.3177354}, pages = {1 -- 8}, language = {en} } @misc{XieLiBegezaetal., author = {Xie, Yufang and Li, Zichao and Begeza, Viktor and Funk, Hannes S. and Fischer, Inga Anita and Zeng, Yu-Jia and Helm, Manfred and Zhou, Shengqiang and Prucnal, Slawomir}, title = {Influence of fabrication parameters on the magnetic and structural properties of Mn5Ge3}, series = {Semiconductor Science and Technology}, volume = {37}, journal = {Semiconductor Science and Technology}, number = {6}, issn = {1361-6641}, doi = {10.1088/1361-6641/ac6689}, pages = {1 -- 8}, abstract = {Mn5Ge3 is a ferromagnetic material with the high potential for spintronic applications. Usually, it is grown by conventional solid state reaction of manganese with germanium using molecular beam epitaxy. Here, we report the structural and magnetic properties of Mn5Ge3 layers grown on Ge substrates using ultrafast-solid phase epitaxy (SPE) method. We investigate the influence of the substrate orientation, Mn layer thickness and annealing parameters on the crystallographic orientation and magnetization of Mn5Ge3. It is shown that after millisecond range SPE, Mn5Ge3 films always have a preferred (100) orientation whether grown on Ge (001) or (111) substrates, which determines the orientation of the magnetization easy axis lying in the film plane along c axis independent of the layer thickness. The Curie temperature of Mn5Ge3 weakly depends on fabrication parameters.}, language = {en} } @misc{FischerBrehmDeSetaetal., author = {Fischer, Inga Anita and Brehm, Moritz and De Seta, Monica and Isella, Giovanni and Paul, Douglas J. and Virgilio, Michele and Capellini, Giovanni}, title = {On-chip infrared photonics with Si-Ge-heterostructures: What is next?}, series = {APL Photonics}, volume = {7}, journal = {APL Photonics}, number = {5}, issn = {2378-0967}, doi = {10.1063/5.0078608}, pages = {050901-1 -- 050901-20}, abstract = {The integration of Ge on Si for photonics applications has reached a high level of maturity: Ge photodetectors are available on the Si platform in foundry processes, and Si/Ge heterostructure multiple quantum-well photodiodes are rapidly progressing toward applications in light modulation. These successes result from decades of development of high-quality material growth and integration, which, more recently, has sparked an increasingly broad field of photonic device research based on Si/Ge heterostructures that extends from quantum cascade lasers to sensors. Here, we highlight selected recent structure and device developments as well as possible future trends that are enabled by the maturity of the SiGe material platform}, language = {en} } @misc{MaiMarschmeyerPeczeketal., author = {Mai, Christian and Marschmeyer, Steffen and Peczek, Anna and Kroh, Aleksandra and Jose, Josmy and Reiter, Sebastian and Fischer, Inga Anita and Wenger, Christian and Mai, Andreas}, title = {Integration Aspects of Plasmonic TiN-based Nano-Hole-Arrays on Ge Photodetectorsin a 200mm Wafer CMOS Compatible Silicon Technology}, series = {ECS Transactions}, volume = {109}, journal = {ECS Transactions}, number = {4}, issn = {1938-5862}, doi = {10.1149/10904.0035ecst}, pages = {35 -- 46}, abstract = {In this work we present the progress in regard to the integration of a surface plasmon resonance refractive index sensor into a CMOS compatible 200 mm wafer silicon-based technology. Our approach pursues the combination of germanium photodetectors with metallic nanohole arrays. The paper is focused on the technology development to fabricate large area photodetectors based on a modern design concept. In a first iteration we achieved a leakage current density of 82 mA/cm2 at reverse bias of 0.5 V and a maximum optical responsivity of 0.103 A/W measured with TE polarized light at λ = 1310 nm and a reversed bias of 1 V. For the realization of nanohole arrays we used thin Titanium nitride (TiN) layers deposited by a sputtering process. We were able to produce very homogenous TiN layers with a thickness deviation of around 10 \% and RMS of 1.413 nm for 150 nm thick TiN layers.}, language = {en} } @misc{SteuerSchwarzOehmeetal., author = {Steuer, Oliver and Schwarz, Daniel and Oehme, Michael and Schulze, J. and Maczko, H. and Kudrawiec, Robert and Fischer, Inga Anita and Heller, R. and H{\"u}bner, R. and Khan, M. M. and Georgiev, Yordan M. and Zhou, Shengqiang and Helm, M. and Prucnal, Slawomir}, title = {Band-gap and strain engineering in GeSn alloys using post-growth pulsed laser melting}, series = {Journal of Physics: Condensed Matter}, volume = {35}, journal = {Journal of Physics: Condensed Matter}, number = {5}, issn = {1361-648X}, doi = {10.1088/1361-648X/aca3ea}, language = {en} } @misc{EfremenkoLaroussiSengueletal., author = {Efremenko, Yulia and Laroussi, Arwa and Seng{\"u}l, Akant and Corley-Wiciak, Agnieszka Anna and Fischer, Inga Anita and Mirsky, Vladimir M.}, title = {Deposition of Polymers on Titanium Nitride Electrodes}, series = {Coatings}, volume = {14}, journal = {Coatings}, number = {2}, issn = {2079-6412}, doi = {10.3390/coatings14020215}, abstract = {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.}, language = {en} } @misc{OleynikBerkmannReiteretal., author = {Oleynik, Paul and Berkmann, Fritz and Reiter, Sebastian and Schlipf, Jon and Ratzke, Markus and Yamamoto, Yuji and Fischer, Inga Anita}, title = {Strong Optical Coupling of Lattice Resonances in a Top-down Fabricated Hybrid Metal-Dielectric Al/Si/Ge Metasurface}, series = {Nano Letters}, volume = {24}, journal = {Nano Letters}, number = {10}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.3c05050}, pages = {3142 -- 3149}, abstract = {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.}, language = {en} } @misc{NitschRatzkePozarowskaetal., author = {Nitsch, Paul-G. and Ratzke, Markus and Pozarowska, Emilia and Flege, Jan Ingo and Alvarado Chavarin, Carlos and Wenger, Christian and Fischer, Inga Anita}, title = {Deposition of reduced ceria thin films by reactive magnetron sputtering for the development of a resistive gas sensor}, series = {Verhandlungen der DPG, Berlin 2024}, journal = {Verhandlungen der DPG, Berlin 2024}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {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.}, language = {en} } @misc{KostoTschammerMoralesetal., author = {Kosto, Yuliia and Tschammer, Rudi and Morales, Carlos and Henkel, Karsten and Flege, Jan Ingo and Ratzke, Markus and Fischer, Inga Anita and Costina, Ioan and Alvarado Chavarin, Carlos and Wenger, Christian}, title = {Rational design and development of room temperature hydrogen sensors compatible with CMOS technology: a necessary step for the coming renewable hydrogen economy}, series = {Proceedings of iCampus Conference Cottbus 2024}, journal = {Proceedings of iCampus Conference Cottbus 2024}, publisher = {AMA Service GmbH}, address = {Wunstorf}, isbn = {978-3-910600-00-3}, doi = {10.5162/iCCC2024/P21}, pages = {182 -- 185}, abstract = {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.}, language = {en} } @misc{BeckerStorckLiuetal., author = {Becker, L. and Storck, Peter and Liu, Y. and Schwalb, G. and Schroeder, Thomas and Fischer, Inga Anita and Albrecht, M.}, title = {Optimizing misfit dislocation glide kinetics for enhanced threading dislocation density reduction in Si1- xGex/Si (001) layers through dynamic growth rate control}, series = {Journal of Applied Physics}, volume = {135}, journal = {Journal of Applied Physics}, number = {20}, issn = {0021-8979}, doi = {10.1063/5.0204318}, pages = {10}, language = {en} } @misc{BerkmannPovolniSchwarzetal., author = {Berkmann, Fritz and Povolni, Pavel and Schwarz, Daniel and Fischer, Inga Anita}, title = {Influence of material and geometry parameters on resonance linewidths of plasmonic modes in gratings made from highly doped Ge1-xSnx}, series = {Journal of Physics D: Applied Physics}, volume = {57}, journal = {Journal of Physics D: Applied Physics}, number = {43}, doi = {10.1088/1361-6463/ad67ea}, pages = {10}, language = {en} } @misc{HayatRatzkeAlvaradoChavarinetal., author = {Hayat, Ahsan and Ratzke, Markus and Alvarado Chavarin, Carlos and Z{\"o}llner, Marvin Hartwig and Corley-Wiciak, Agnieszka Anna and Schubert, Markus Andreas and Wenger, Christian and Fischer, Inga Anita}, title = {Structural and morphological properties of CeO2 films deposited by radio frequency magnetron sputtering for back-end-of-line integration}, series = {Thin Solid Films}, volume = {807}, journal = {Thin Solid Films}, issn = {0040-6090}, doi = {10.1016/j.tsf.2024.140547}, pages = {3}, language = {en} } @misc{ReiterSenguelMaietal., author = {Reiter, Sebastian and Seng{\"u}l, Akant and Mai, Christian and Spirito, Davide and Wenger, Christian and Fischer, Inga Anita}, title = {On-chip refractive index sensors based on plasmonic TiN Nanohole Arrays}, series = {2024 IEEE Silicon Photonics Conference (SiPhotonics)}, journal = {2024 IEEE Silicon Photonics Conference (SiPhotonics)}, isbn = {979-8-3503-9404-7}, issn = {1949-209X}, doi = {10.1109/SiPhotonics60897.2024.10544048}, pages = {2}, language = {de} } @misc{Fischer, author = {Fischer, Inga Anita}, title = {CMOS-compatible metasurfaces integrated with optoelectronic devices: tuning light-matter interaction at the nanoscale}, series = {Technical Digest Series (Optica Publishing Group, 2024), paper SM2L.7}, journal = {Technical Digest Series (Optica Publishing Group, 2024), paper SM2L.7}, isbn = {978-1-957171-39-5}, doi = {10.1364/CLEO_SI.2024.SM2L.7}, language = {en} } @misc{JoseMaiWengeretal., author = {Jose, Josmy and Mai, Christian and Wenger, Christian and Fischer, Inga Anita}, title = {Integration concept of plasmonic TiN nanohole arrays in a 200 mm BiCMOS Si technology for refractive index sensor applications}, series = {iCCC2024 - iCampµs Cottbus Conference}, journal = {iCCC2024 - iCampµs Cottbus Conference}, doi = {10.5162/iCCC2024/7.2}, pages = {96 -- 99}, language = {de} } @misc{MaiPeczekKrohetal., author = {Mai, Christian and Peczek, Anna and Kroh, Aleksandra and Jose, Josmy and Reiter, Sebastian and Wenger, Christian and Fischer, Inga Anita}, title = {Towards a CMOS compatible refractive index sensor: cointegration of TiN nanohole arrays and Ge photodetectors in a 200 mm wafer silicon technology}, series = {Optics Express}, volume = {32}, journal = {Optics Express}, number = {17}, publisher = {Optica Publishing Group}, issn = {1094-4087}, doi = {10.1364/OE.530081}, pages = {29099 -- 29111}, abstract = {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\%.}, language = {en} } @misc{BerkmannSteuerGanssetal., author = {Berkmann, Fritz and Steuer, Oliver and Ganss, Fabian and Prucnal, Slawomir and Schwarz, Daniel and Fischer, Inga Anita and Schulze, J{\"o}rg}, title = {Sharp MIR plasmonic modes in gratings made of heavily doped pulsed laser-melted Ge1-xSnx}, series = {Optical Materials Express}, volume = {13}, journal = {Optical Materials Express}, number = {3}, issn = {2159-3930}, doi = {10.1364/OME.479637}, pages = {752 -- 763}, language = {en} } @misc{WeisshauptFunkOehmeetal., author = {Weißhaupt, David and Funk, Hannes S. and Oehme, Michael and Bloos, Dominik and Berkmann, Fritz and Seidel, Lukas and Fischer, Inga Anita and Schulze, J{\"o}rg}, title = {High mobility Ge 2DHG based MODFETs for low-temperature applications}, series = {Semiconductor Science and Technology}, volume = {38}, journal = {Semiconductor Science and Technology}, number = {3}, issn = {1361-6641}, doi = {10.1088/1361-6641/acb22f}, language = {en} } @misc{ReiterHanMaietal., author = {Reiter, Sebastian and Han, Weijia and Mai, Christian and Spirito, Davide and Jose, Josmy and Z{\"o}llner, Marvin Hartwig and Fursenko, Oksana and Schubert, Markus Andreas and Stemmler, Ivo and Wenger, Christian and Fischer, Inga Anita}, title = {Titanium Nitride Plasmonic Nanohole Arrays for CMOS-compatible integrated refractive index sensing: influence of layer thickness on optical properties}, series = {Plasmonics}, journal = {Plasmonics}, issn = {1557-1963}, doi = {10.1007/s11468-023-01810-3}, pages = {1 -- 13}, language = {en} } @misc{SchlipfBerkmannYamamotoetal., author = {Schlipf, Jon and Berkmann, Fritz and Yamamoto, Yuji and Reichenbach, Marc and Veleski, Mitko and Kawaguchi, Yuma and M{\"o}rz, Florian and Tomm, Jens W. and Weißhaupt, David and Fischer, Inga Anita}, title = {Robust Si/Ge heterostructure metasurfaces as building blocks for wavelength-selective photodetectors}, series = {Applied Physics Letters}, volume = {122}, journal = {Applied Physics Letters}, number = {12}, issn = {1077-3118}, doi = {10.1063/5.0134458}, language = {en} } @misc{HanReiterSchlipfetal., author = {Han, Weijia and Reiter, Sebastian and Schlipf, Jon and Mai, Christian and Spirito, Davide and Jose, Josmy and Wenger, Christian and Fischer, Inga Anita}, title = {Strongly enhanced sensitivities of CMOS compatible plasmonic titanium nitride nanohole arrays for refractive index sensing under oblique incidence}, series = {Optics Express}, volume = {31}, journal = {Optics Express}, number = {11}, issn = {1094-4087}, doi = {10.1364/OE.481993}, pages = {17389 -- 17407}, abstract = {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-P{\´e}rot 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.}, language = {en} } @misc{TetznerSeifertSkibitzkietal., author = {Tetzner, Henriette and Seifert, W. and Skibitzki, Oliver and Yamamoto, Yuji and Lisker, Marco and Mirza, M. M. and Fischer, Inga Anita and Paul, Douglas J. and De Seta, Monica and Capellini, Giovanni}, title = {Unintentional p-type conductivity in intrinsic Ge-rich SiGe/Ge heterostructures grown on Si(001)}, series = {Applied Physics Letter}, volume = {122}, journal = {Applied Physics Letter}, number = {24}, issn = {1077-3118}, doi = {10.1063/5.0152962}, language = {en} } @misc{HayatSpiritoCorleyWiciaketal., author = {Hayat, Ahsan and Spirito, Davide and Corley-Wiciak, Agnieszka Anna and Schubert, Markus Andreas and Masood, Maria and Reichmann, Felix and Ratzke, Markus and Capellini, Giovanni and Fischer, Inga Anita}, title = {MBE-based growth of Sn-rich quantum wells and dots at low Sn deposition rates}, series = {Materials Science in Semiconductor Processing}, volume = {165}, journal = {Materials Science in Semiconductor Processing}, issn = {1873-4081}, doi = {10.1016/j.mssp.2023.107693}, language = {en} } @misc{SteuerLiedkeButterlingetal., author = {Steuer, O. and Liedke, Maciej O. and Butterling, M. and Schwarz, D. and Schulze, J. and Li, Z. and Wagner, A. and Fischer, Inga Anita and H{\"u}bner, R. and Zhou, S.}, title = {Evolution of point defects in pulsed-laser-melted Ge1-xSnx probed by positron annihilation lifetime spectroscopy}, series = {Journal of Physics: Condensed Matter}, volume = {36}, journal = {Journal of Physics: Condensed Matter}, number = {8}, issn = {0953-8984}, doi = {10.1088/1361-648X/ad0a10}, pages = {1 -- 11}, abstract = {Direct-band-gap Germanium-Tin alloys (Ge1-xSnx) with high carrier mobilities are promising materials for nano- and optoelectronics. The concentration of open volume defects in the alloy, such as Sn and Ge vacancies, influences the final device performance. In this article, we present an evaluation of the point defects in molecular-beam-epitaxy grown Ge1-xSnx films treated by post-growth nanosecond-range pulsed laser melting (PLM). Doppler broadening - variable energy positron annihilation spectroscopy and variable energy positron annihilation lifetime spectroscopy are used to investigate the defect nanostructure in the Ge1-xSnx films exposed to increasing laser energy density. The experimental results, supported with ATomic SUPerposition calculations, evidence that after PLM, the average size of the open volume defects increases, which represents a raise in concentration of vacancy agglomerations, but the overall defect density is reduced as a function of the PLM fluence. At the same time, the positron annihilation spectroscopy analysis provides information about dislocations and Ge vacancies decorated by Sn atoms. Moreover, it is shown that the PLM reduces the strain in the layer, while dislocations are responsible for trapping of Sn and formation of small Sn-rich-clusters.}, language = {en} } @misc{WenShaikhSteueretal., author = {Wen, Shuyu and Shaikh, Mohd Saif and Steuer, Oliver and Prucnal, Slawomir and Grenzer, J{\"o}rg and H{\"u}bner, Ren{\´e} and Turek, Marcin and Pyszniak, Krzysztof and Reiter, Sebastian and Fischer, Inga Anita and Georgiev, Yordan M. and Helm, Manfred and Wu, Shaoteng and Luo, Jun-Wei and Zhou, Shengqiang and Berenc{\´e}n, Yonder}, title = {Room-temperature extended short-wave infrared GeSn photodetectors realized by ion beam techniques}, series = {Applied Physics Letters}, volume = {123}, journal = {Applied Physics Letters}, number = {8}, issn = {0003-6951}, doi = {10.1063/5.0166799}, pages = {1 -- 7}, abstract = {GeSn alloys hold great promise as high-performance, low-cost, near- and short-wavelength infrared photodetectors with the potential to replace the relatively expensive and currently market-dominant InGaAs- and InSb-based photodetectors. In this Letter, we demonstrate room-temperature GeSn pn photodetectors fabricated by a complementary metal-oxide-semiconductor compatible process, involving Sn and P ion implantation and flash-lamp annealing prior to device fabrication. The fabrication process enables the alloying of Ge with Sn at concentrations up to 4.5\% while maintaining the high-quality single-crystalline structure of the material. This allows us to create Ge0.955Sn0.045 pn photodetectors with a low dark current density of 12.8 mA/cm2 and a relatively high extended responsivity of 0.56 A/W at 1.71 μm. These results pave the way for the implementation of a cost-effective, scalable, and CMOS-compatible short-wavelength infrared detector technology.}, language = {en} } @misc{KalraAlvaradoChavarinNitschetal., author = {Kalra, Amanpreet and Alvarado Chavarin, Carlos and Nitsch, Paul-Gregor and Tschammer, Rudi and Flege, Jan Ingo and Ratzke, Markus and Zoellner, Marvin Hartwig and Schubert, Markus Andreas and Wenger, Christian and Fischer, Inga Anita}, title = {Deposition of CeOₓ/SnOₓ-based thin films via RF magnetron sputtering for resistive gas sensing applications}, series = {Physica B, Condensed matter}, volume = {723}, journal = {Physica B, Condensed matter}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0921-4526}, doi = {10.1016/j.physb.2025.418098}, pages = {1 -- 7}, abstract = {Cerium oxide-tin oxide (CeOx/SnOx) thin films with varying Sn content were deposited using RF magnetron sputtering and investigated for hydrogen sensing applications. Structural, compositional, and morphological properties were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). Gas sensing measurements showed effective hydrogen detection at room temperature, with the sensitivity strongly influenced by Sn content and oxygen vacancy concentration. Higher Sn concentration enhanced the sensing response, which was correlated with microstructural features obtained from AFM and EDX, as well as with the presence of Ce3+ and Ce4+ oxidation states identified by XPS. This study highlights the potential of CeOx/SnOx thin films for possible back-end-of-line integration and provides proof-of-principle for room-temperature hydrogen sensing.}, language = {en} } @misc{SenguelReiterLotfietal., author = {Seng{\"u}l, Akant and Reiter, Sebastian and Lotfi, Zahra and Efremenko, Julia and Laroussi, Arwa and Corley-Wiciak, Agnieszka Anna and Ratzke, Markus and Mirsky, Vladimir M. and Wenger, Christian and Fischer, Inga Anita}, title = {Titanium nitride plasmonic nanohole arrays with polymer coating : optical properties and their humidity-induced modifications}, series = {Optical materials express}, volume = {16}, journal = {Optical materials express}, number = {2}, publisher = {Optica Publishing Group}, address = {Washington, DC}, issn = {2159-3930}, doi = {10.1364/ome.578871}, pages = {184 -- 196}, abstract = {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.}, language = {en} } @misc{SchlipfCutoloManganellietal., author = {Schlipf, Jon and Cutolo, Maria Alessandra and Manganelli, Costanza Lucia and Reiter, Sebastian and Seibold, G{\"o}tz and Skibitzki, Oliver and Wenger, Christian and Fischer, Inga Anita}, title = {Fabrication and optical characterization of CMOS-compatible honeycomb-like large-scale lattices of near-field coupled plasmonic TiN nanotriangles}, series = {Advanced optical materials}, volume = {2025}, journal = {Advanced optical materials}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2195-1071}, doi = {10.1002/adom.202403408}, pages = {1 -- 8}, abstract = {Honeycomb-like plasmonic titanium nitride nanotriangle arrays defined by photolithography and fabricated in a modified silicon-germanium electronic-photonic integrated circuit process in a state-of-the-art pilot line. The nanotriangle arrays are characterized in experiments and simulations. The momentum-dependent reflectance spectra exhibit not only features that are consistent with surface lattice resonances in the honeycomb lattice but also minima governed by near-field coupling of the individual nanotriangles. The optical characterization results in combination with simulation-based predictions indicate that such nanotriangle arrays are capable of supporting collective plasmonic resonances that can be described as massless Dirac particles. The fabrication approach opens up the possibility of integrating the structures into device fabrication processes, and avenues toward near-infrared sensing and communication applications are predicted.}, language = {en} }