@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{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} }