@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{CapistaLukoseMajnoonetal.,
author = {Capista, Daniele and Lukose, Rasuole and Majnoon, Farnaz and Lisker, Marco and Wenger, Christian and Lukosius, Mindaugas},
title = {Optimization of the metal deposition process for the accurate estimation of Low Metal-Graphene Contact-Resistance},
series = {47th MIPRO ICT and Electronics Convention (MIPRO), 20-24 May 2024, Opatija, Croatia},
journal = {47th MIPRO ICT and Electronics Convention (MIPRO), 20-24 May 2024, Opatija, Croatia},
isbn = {979-8-3503-8250-1},
issn = {2623-8764},
doi = {10.1109/MIPRO60963.2024.10569895},
pages = {5},
language = {en}
}
@misc{MaldonadoCantudoSwamyReddyetal.,
author = {Maldonado, David and Cantudo, Antonio and Swamy Reddy, Keerthi Dorai and Pechmann, Stefan and Uhlmann, Max and Wenger, Christian and Roldan, Juan Bautista and P{\´e}rez, Eduardo},
title = {Influence of stop and gate voltage on resistive switching of 1T1R HfO2-based memristors, a modeling and variability analysis},
series = {Materials Science in Semiconductor Processing},
volume = {182},
journal = {Materials Science in Semiconductor Processing},
issn = {1873-4081},
doi = {10.1016/j.mssp.2024.108726},
pages = {9},
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{VinuesaGarciaPerezetal.,
author = {Vinuesa, Guillermo and Garc{\´i}a, H{\´e}ctor and P{\´e}rez, Eduardo and Wenger, Christian and {\´I}{\~n}iguez de la Torre, Ignacio and Gonz{\´a}lez, Tom{\´a}s and Due{\~n}as, Salvador and Cast{\´a}n, Helena},
title = {On the asymmetry of Resistive Switching Transitions},
series = {Electronics},
volume = {13},
journal = {Electronics},
number = {13},
publisher = {MDPI},
issn = {2079-9292},
doi = {10.3390/electronics13132639},
pages = {11},
abstract = {In this study, the resistive switching phenomena in TiN/Ti/HfO2/Ti metal-insulator-metal stacks is investigated, mainly focusing on the analysis of set and reset transitions. The electrical measurements in a wide temperature range reveal that the switching transitions require less voltage (and thus, less energy) as temperature rises, with the reset process being much more temperature sensitive. The main conduction mechanism in both resistance states is Space-charge-limited Conduction, but the high conductivity state also shows Schottky emission, explaining its temperature dependence. Moreover, the temporal evolution of these transitions reveals clear differences between them, as their current transient response is completely different. While the set is sudden, the reset process development is clearly non-linear, closely resembling a sigmoid function. This asymmetry between switching processes is of extreme importance in the manipulation and control of the multi-level characteristics and has clear implications in the possible applications of resistive switching devices in neuromorphic computing.},
language = {en}
}
@misc{StrobelAlvaradoChavarinKnautetal.,
author = {Strobel, Carsten and Alvarado Chavarin, Carlos and Knaut, Martin and Albert, Matthias and Heinzig, Andr{\´e} and Gummadi, Likhith and Wenger, Christian and Mikolajick, Thomas},
title = {p-Type Schottky contacts for graphene adjustable-Barrier phototransistors},
series = {Nanomaterials},
volume = {14},
journal = {Nanomaterials},
number = {13},
editor = {Giannazzo, Filippo and Agnello, Simonpietro and Seravalli, Luca and Bondino, Federica},
publisher = {MDPI},
issn = {2079-4991},
doi = {10.3390/nano14131140},
abstract = {The graphene adjustable-barriers phototransistor is an attractive novel device for potential high speed and high responsivity dual-band photodetection. In this device, graphene is embedded between the semiconductors silicon and germanium. Both n-type and p-type Schottky contacts between graphene and the semiconductors are required for this device. While n-type Schottky contacts are widely investigated, reports about p-type Schottky contacts between graphene and the two involved semiconductors are scarce. In this study, we demonstrate a p-type Schottky contact between graphene and p-germanium. A clear rectification with on-off ratios of close to 10 3 (±5 V) and a distinct photoresponse at telecommunication wavelengths in the infrared are achieved. Further, p-type silicon is transferred to or deposited on graphene, and we also observe rectification and photoresponse in the visible range for some of these p-type Schottky junctions. These results are an important step toward the realization of functional graphene adjustable-barrier phototransistors.},
language = {en}
}
@misc{MoralesPlateMarthetal.,
author = {Morales, Carlos and Plate, Paul and Marth, Ludwig and Naumann, Franziska and Kot, Małgorzata and Janowitz, Christoph and Kus, Peter and Z{\"o}llner, Marvin Hartwig and Wenger, Christian and Henkel, Karsten and Flege, Jan Ingo},
title = {Bottom-up design of a supercycle recipe for atomic layer deposition of tunable Indium Gallium Zinc Oxide thin films},
series = {ACS Applied Electronic Materials},
volume = {6},
journal = {ACS Applied Electronic Materials},
number = {8},
publisher = {American Chemical Society (ACS)},
issn = {2637-6113},
doi = {10.1021/acsaelm.4c00730},
pages = {5694 -- 5704},
abstract = {We present a successful bottom-up approach to design a generic plasma-enhanced atomic layer deposition (PEALD) supercycle recipe to grow high-quality indium gallium zinc oxide (IGZO) thin films with tunable composition at a relatively low temperature of 150 °C. In situ real-time ellipsometric characterization in combination with ex situ complementary techniques has been used to optimize the deposition process and quality of the films by identifying and solving growth challenges such as degree of oxidation, nucleation delays, or elemental composition. The developed supercycle approach enables facile control of the target composition by adapting the subcycle ratios within the supercycle process. Compared to other low-temperature deposition techniques resulting in amorphous films, our PEALD-IGZO process at 150 °C results in nearly amorphous, nanocrystalline films. The preparation of IGZO films at low temperature by a supercycle PEALD approach allows controlling the thickness, composition, and electrical properties while preventing thermally induced segregation.},
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{FritscherSinghRizzietal.,
author = {Fritscher, Markus and Singh, Simranjeet and Rizzi, Tommaso and Baroni, Andrea and Reiser, Daniel and Mallah, Maen and Hartmann, David and Bende, Ankit and Kempen, Tim and Uhlmann, Max and Kahmen, Gerhard and Fey, Dietmar and Rana, Vikas and Menzel, Stephan and Reichenbach, Marc and Krstic, Milos and Merchant, Farhad and Wenger, Christian},
title = {A flexible and fast digital twin for RRAM systems applied for training resilient neural networks},
series = {Scientific Reports},
volume = {14},
journal = {Scientific Reports},
number = {1},
publisher = {Springer Science and Business Media LLC},
issn = {2045-2322},
doi = {10.1038/s41598-024-73439-z},
pages = {13},
abstract = {Resistive Random Access Memory (RRAM) has gained considerable momentum due to its non-volatility and energy efficiency. Material and device scientists have been proposing novel material stacks that can mimic the "ideal memristor" which can deliver performance, energy efficiency, reliability and accuracy. However, designing RRAM-based systems is challenging. Engineering a new material stack, designing a device, and experimenting takes significant time for material and device researchers. Furthermore, the acceptability of the device is ultimately decided at the system level. We see a gap here where there is a need for facilitating material and device researchers with a "push button" modeling framework that allows to evaluate the efficacy of the device at system level during early device design stages. Speed, accuracy, and adaptability are the fundamental requirements of this modelling framework. In this paper, we propose a digital twin (DT)-like modeling framework that automatically creates RRAM device models from device measurement data. Furthermore, the model incorporates the peripheral circuit to ensure accurate energy and performance evaluations. We demonstrate the DT generation and DT usage for multiple RRAM technologies and applications and illustrate the achieved performance of our GPU implementation. We conclude with the application of our modeling approach to measurement data from two distinct fabricated devices, validating its effectiveness in a neural network processing an Electrocardiogram (ECG) dataset and incorporating Fault Aware Training (FAT).},
language = {en}
}
@misc{LukosiusLukoseDubeyetal.,
author = {Lukosius, Mindaugas and Lukose, Rasuolė and Dubey, P. K. and Raju, A. I. and Capista, Daniele and Lisker, Marco and Mai, A. and Wenger, Christian},
title = {Graphene for photonic applications},
series = {2024 47th MIPRO ICT and Electronics Convention (MIPRO)},
journal = {2024 47th MIPRO ICT and Electronics Convention (MIPRO)},
publisher = {IEEE},
isbn = {979-8-3503-8250-1},
issn = {2623-8764},
doi = {10.1109/MIPRO60963.2024.10569652},
pages = {1614 -- 1618},
abstract = {Integrating graphene into Silicon Complementary Metal-Oxide-Semiconductor (CMOS) technology for photonic applications holds immense promise, but it encounters challenges in establishing large-scale graphene processes. These challenges encompass growth through techniques like Chemical Vapor Deposition (CVD), transfer, encapsulation, and contact formation within a routine 200mm wafer pilot line typically utilized for integrated circuit fabrication. This study is dedicated to exploring various facets of graphene research within a 200 mm pilot line, with a focus on overcoming challenges through the fabrication of proof-of-concept photonic graphene-based devices. The synthesis of graphene targeted epi-Ge(100)/Si(100) substrates, grown within the IHP pilot line, showcasing the potential for high-quality graphene deposition across 200mm wafers. Alternatively, employing different orientations such as (110) has been explored to enhance graphene mobility, achieving a remarkable mobility of 2300 cm 2 /Vs at present. The study systematically investigates graphene quality, thickness, and homogeneity utilizing techniques such as Raman spectroscopy, Atomic Force Microscopy (AFM), and Scanning Electron Microscopy (SEM). Additionally, simulations and fabrication of the graphene ring modulators have been conducted at both the component and device levels, incorporating realistic graphene properties. These results indicate a modulation depth of 1.6 dB/μm and a 3dB bandwidth of 7 GHz, showcasing the potential of graphene-based photonic devices for high-speed communication applications.},
language = {en}
}