@misc{KalettaWipfFraschkeetal., author = {Kaletta, Udo Christian and Wipf, Christian and Fraschke, Mirko and Wolansky, Dirk and Schubert, Markus Andreas and Schroeder, Thomas and Wenger, Christian}, title = {AlN/SiO2/Si3N4/Si(100) based CMOS compatible surface acoustic wave filter with -12.8 dB minimum insertion loss}, series = {IEEE Transactions on Electron Devices}, volume = {62}, journal = {IEEE Transactions on Electron Devices}, number = {3}, issn = {0018-9383}, doi = {10.1109/TED.2015.2395443}, pages = {764 -- 768}, language = {en} } @misc{BertaudWalczykWalczyketal., author = {Bertaud, Thomas and Walczyk, Damian and Walczyk, Christian and Kubotsch, S. and Wenger, Christian and Schr{\"o}der, Thomas and Vall{\´e}e, Christophe and Gonon, P. and Mannequin, C. and Jousseaume, V. and Grampeix, Helen}, title = {Resistive Switching of HfO2-based MIM diodes: Impact of the Top Electrode Materials}, series = {Thin Solid Films}, volume = {520}, journal = {Thin Solid Films}, number = {14}, issn = {0040-6090}, pages = {4551 -- 4555}, language = {en} } @misc{BertaudWalczykSowinskaetal., author = {Bertaud, Thomas and Walczyk, Damian and Sowinska, Małgorzata and Wolansky, Dirk and Tillack, Bernd and Schoof, Gunther and Korolevych, R. and Wenger, Christian and Thiess, Sebastian and Schroeder, Thomas and Walczyk, Christian}, title = {HfO2-based RRAM for Embedded Nonvolatile Memory: From Materials Science to Integrated 1T1R RRAM Arrays}, series = {ECS transactions}, volume = {50}, journal = {ECS transactions}, number = {4}, issn = {1938-6737}, pages = {21 -- 26}, language = {en} } @misc{PerezMaldonadoAcaletal., author = {P{\´e}rez, Eduardo and Maldonado, David and Acal, Christian and Ruiz-Castro, Juan Eloy and Aguilera, Ana Mar{\´i}a and Jimenez-Molinos, Francisco and Roldan, Juan Bautista and Wenger, Christian}, title = {Advanced Temperature Dependent Statistical Analysis of Forming Voltage Distributions for Three Different HfO2-Based RRAM Technologies}, series = {Solid State Electronics}, volume = {176}, journal = {Solid State Electronics}, issn = {0038-1101}, pages = {6}, abstract = {In this work, voltage distributions of forming operations are analyzed by using an advanced statistical approach based on phase-type distributions (PHD). The experimental data were collected from batches of 128 HfO2-based RRAM devices integrated in 4-kbit arrays. Three di erent switching oxides, namely, polycrystalline HfO2, amorphous HfO2, and Al-doped HfO2, were tested in the temperature range from -40 to 150 oC. The variability of forming voltages has been usually studied by using the Weibull distribution (WD). However, the performance of the PHD analysis demonstrated its ability to better model this crucial operation. The capacity of the PHD to reproduce the experimental data has been validated by means of the Kolmogorov-Smirnov test, while the WD failed in many of the cases studied. In addition, PHD allows to extract information about intermediate probabilistic states that occur in the forming process and the transition probabilities between them; in this manner, we can deepen on the conductive lament formation physics. In particular, the number of intermediate states can be related to the device variability.}, 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{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{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{DerschRoemerPerezetal., author = {Dersch, Nadine and Roemer, Christian and Perez, Eduardo and Wenger, Christian and Schwarz, Mike and I{\~n}{\´i}guez, Benjam{\´i}n and Kloes, Alexander}, title = {Fast circuit simulation of memristive crossbar arrays with bimodal stochastic synaptic weights}, series = {2024 IEEE Latin American Electron Devices Conference (LAEDC)}, journal = {2024 IEEE Latin American Electron Devices Conference (LAEDC)}, publisher = {IEEE}, isbn = {979-8-3503-6130-8}, issn = {979-8-3503-6129-2}, doi = {10.1109/LAEDC61552.2024.10555829}, pages = {1 -- 4}, abstract = {This paper presents an approach for highly efficient circuit simulation of hardware-based artificial neural networks by using memristive crossbar array architectures. There are already possibilities to test neural networks with stochastic weights via simulations like the macro model NeuroSim. However, the noise-based variability approach offers more realistic setting options including elements of a classical circuit simulation for more precise analysis of neural networks. With this approach, statistical parameter fluctuations can be simulated based on different distribution functions of devices. In Cadence Virtuoso, a simulation of a crossbar array with 10 synaptic weights following a bimodal distribution, the new approach shows a 1,000x speedup compared to a Monte Carlo simulation. Initial tests of a memristive crossbar array with over 15,000 stochastic weights to classify the MNIST dataset show that the new approach can be used to test the functionality of hardware-based neural networks.}, 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{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{DerschPerezBoschQuesadaPerezetal., author = {Dersch, Nadine and Perez-Bosch Quesada, Emilio and P{\´e}rez, Eduardo and Wenger, Christian and Roemer, Christian and Schwarz, Mike and Kloes, Alexander}, title = {Efficient circuit simulation of a memristive crossbar array with synaptic weight variability}, series = {Solid State Electronics}, volume = {209}, journal = {Solid State Electronics}, issn = {0038-1101}, doi = {10.1016/j.sse.2023.108760}, abstract = {In this paper, we present a method for highly-efficient circuit simulation of a hardware-based artificial neural network realized in a memristive crossbar array. The statistical variability of the devices is considered by a noise-based simulation technique. For the simulation of a crossbar array with 8 synaptic weights in Cadence Virtuoso the new approach shows a more than 200x speed improvement compared to a Monte Carlo approach, yielding the same results. In addition, first results of an ANN with more than 15,000 memristive devices classifying test data of the MNIST dataset are shown, for which the speed improvement is expected to be several orders of magnitude. Furthermore, the influence on the classification of parasitic resistances of the connection lines in the crossbar is shown.}, language = {en} } @misc{ReiterRatzkeNitschetal., author = {Reiter, Sebastian and Ratzke, Markus and Nitsch, Paul-Gregor and Mai, Christian and Spirito, Davide and Corley-Wiciak, Agnieszka Anna and Wenger, Christian and Fischer, Inga A.}, title = {Optical response of titanium nitride plasmonic nanohole arrays : impact of square and hexagonal array geometry, pitch, and nanohole diameter}, series = {Plasmonics}, volume = {20}, journal = {Plasmonics}, publisher = {Springer}, address = {New York, NY}, doi = {10.1007/s11468-025-02934-4}, pages = {8825 -- 8834}, abstract = {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.}, language = {en} } @misc{LupinaDabrowskiFormaneketal., author = {Lupina, Grzegorz and Dabrowski, Jarek Marek and Formanek, Peter and Schmeißer, Dieter and Sorge, Roland and Wenger, Christian and Zaumseil, Peter and M{\"u}ssig, Hans-Joachim}, title = {Solid-state reaction between Pr and SiO2 studied by photoelectron spectroscopy and ab initio calculations}, series = {Materials Science in Semiconductor Processing}, volume = {7}, journal = {Materials Science in Semiconductor Processing}, number = {4-6}, issn = {1369-8001}, pages = {215 -- 220}, abstract = {We report on the structural and electrical properties of Pr-based high-k dielectric films fabricated by solid-state reaction between metallic Pr and SiO2 underlayers. A non-destructive depth profiling using synchrotron radiation excited photoelectron spectroscopy (SR-PES), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were employed to examine the chemical composition and microstructure. Ab initio calculations were done to gain insight into the physical processes involved. SR-PES results indicate that Pr deposition at room temperature (RT) leads to the formation of a Pr silicide and a Pr oxide, what is in good agreement with the scenario expected from ab initio calculations. As revealed by TEM and electrical measurements, oxidation of the reacted structures, followed by annealing, results in a stacked dielectric composed of a SiO2-based buffer with an enhanced permittivity and a Pr silicate film with a high dielectric constant. The leakage current density of 10-4 A/cm2 was measured for stacks with capacitance equivalent thickness (CET) of 1.5 nm prepared by evaporation of the Pr layer on a 1.8 nm SiO2 film, followed by oxidation in air ambient and annealing in N2 atmosphere. The capacitance-voltage (C-V) curves exhibit a large flatband voltage (VFB) shift indicating the presence of a positive charge in the stack. Switching away from the Al contacts to Au gate electrodes introduces a significant reduction of the VFB by 1.3 eV, what is much more than the change expected from the work function difference between Al and Au (not, vert, similar0.9 eV). This in turn implies that VFB is strongly affected by the gate interface electrode.}, language = {en} } @misc{MuessigDabrowskiWengeretal., author = {M{\"u}ssig, Hans-Joachim and Dabrowski, Jarek Marek and Wenger, Christian and Lupina, Grzegorz and Sorge, Roland and Formanek, Peter and Zaumseil, Peter and Schmeißer, Dieter}, title = {Ultrathin Dielectric Films Grown by Solid Phase Reaction of Pr with SiO2}, series = {MRS Proceedings}, volume = {811}, journal = {MRS Proceedings}, issn = {1946-4274}, pages = {D7.10.}, language = {en} }