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 -