TY - GEN
A1 - Mai, Christian
A1 - Marschmeyer, Steffen
A1 - Peczek, Anna
A1 - Kroh, Aleksandra
A1 - Jose, Josmy
A1 - Reiter, Sebastian
A1 - Fischer, Inga Anita
A1 - Wenger, Christian
A1 - Mai, Andreas
T1 - Integration Aspects of Plasmonic TiN-based Nano-Hole-Arrays on Ge Photodetectorsin a 200mm Wafer CMOS Compatible Silicon Technology
T2 - ECS Transactions
N2 - 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.
KW - plasmonics
KW - nanohole array
KW - germanium detector
Y1 - 2022
U6 - https://doi.org/10.1149/10904.0035ecst
SN - 1938-5862
VL - 109
IS - 4
SP - 35
EP - 46
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 - 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 -
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 - 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 - 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 - 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 - 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 - Kalra, Amanpreet
A1 - Alvarado Chavarin, Carlos
A1 - Nitsch, Paul-Gregor
A1 - Tschammer, Rudi
A1 - Flege, Jan Ingo
A1 - Ratzke, Markus
A1 - Zoellner, Marvin Hartwig
A1 - Schubert, Markus Andreas
A1 - Wenger, Christian
A1 - Fischer, Inga Anita
T1 - Deposition of CeOₓ/SnOₓ-based thin films via RF magnetron sputtering for resistive gas sensing applications
T2 - Physica B, Condensed matter
N2 - 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.
KW - RF magnetron sputtering
KW - CeOx/SnOx thin film
KW - Room temperature
KW - Hydrogen sensing
Y1 - 2026
U6 - https://doi.org/10.1016/j.physb.2025.418098
SN - 0921-4526
VL - 723
SP - 1
EP - 7
PB - Elsevier BV
CY - Amsterdam
ER -
TY - GEN
A1 - Schlipf, Jon
A1 - Cutolo, Maria Alessandra
A1 - Manganelli, Costanza Lucia
A1 - Reiter, Sebastian
A1 - Seibold, Götz
A1 - Skibitzki, Oliver
A1 - Wenger, Christian
A1 - Fischer, Inga Anita
T1 - Fabrication and optical characterization of CMOS-compatible honeycomb-like large-scale lattices of near-field coupled plasmonic TiN nanotriangles
T2 - Advanced optical materials
N2 - 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.
KW - Plasmonic Nanostructures
KW - Optics of Nanostructures
Y1 - 2025
UR - https://advanced.onlinelibrary.wiley.com/doi/epdf/10.1002/adom.202403408
U6 - https://doi.org/10.1002/adom.202403408
SN - 2195-1071
VL - 2025
SP - 1
EP - 8
PB - Wiley-VCH
CY - Weinheim
ER -