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  • Publikationen 2020

Publikationen 2020

seit Januar 2020

(1) Separation, Characterization, and Handling of Microalgae by Dielectrophoresis
V. Abt, F. Gringel, A. Han, P. Neubauer, M. Birkholz
Microorganisms 8(4), 540 (2020)
DOI: 10.3390/microorganisms8040540, (Bioelectronics)
Microalgae biotechnology has a high potential for sustainable bioproduction of diverse high-value biomolecules. Some of the main bottlenecks in cell-based bioproduction, and more specifically in microalgae-based bioproduction, are due to insufficient methods for rapid and efficient cell characterization, which contributes to having only a few industrially established microalgal species in commercial use. Dielectrophoresis-based microfluidic devices have been long established as promising tools for label-free handling, characterization, and separation of broad ranges of cells. The technique is based on differences in dielectric properties and sizes, which results in different degrees of cell movement under an applied inhomogeneous electrical field. The method has also earned interest for separating microalgae based on their intrinsic properties, since their dielectric properties may significantly change during bioproduction, in particular for lipid-producing species. Here, we provide a comprehensive review of dielectrophoresis-based microfluidic devices that are used for handling, characterization, and separation of microalgae. Additionally, we provide a perspective on related areas of research in cell-based bioproduction that can benefit from dielectrophoresis-based microdevices. This work provides key information that will be useful for microalgae researchers to decide whether dielectrophoresis and which method is most suitable for their particular application.

(2) Separation, Characterization, and Handling of Microalgae by Dielectrophoresis
V. Abt, F. Gringel, A. Han, P. Neubauer, M. Birkholz
Microorganisms 8(4), 540 (2020)
DOI: 10.3390/microorganisms8040540, (SepaDiElo)
Microalgae biotechnology has a high potential for sustainable bioproduction of diverse high-value biomolecules. Some of the main bottlenecks in cell-based bioproduction, and more specifically in microalgae-based bioproduction, are due to insufficient methods for rapid and efficient cell characterization, which contributes to having only a few industrially established microalgal species in commercial use. Dielectrophoresis-based microfluidic devices have been long established as promising tools for label-free handling, characterization, and separation of broad ranges of cells. The technique is based on differences in dielectric properties and sizes, which results in different degrees of cell movement under an applied inhomogeneous electrical field. The method has also earned interest for separating microalgae based on their intrinsic properties, since their dielectric properties may significantly change during bioproduction, in particular for lipid-producing species. Here, we provide a comprehensive review of dielectrophoresis-based microfluidic devices that are used for handling, characterization, and separation of microalgae. Additionally, we provide a perspective on related areas of research in cell-based bioproduction that can benefit from dielectrophoresis-based microdevices. This work provides key information that will be useful for microalgae researchers to decide whether dielectrophoresis and which method is most suitable for their particular application.

(3) Investigation of the Oxidation Behavior of Graphene/Ge(001) Versus Graphene/Ge(110) Systems
F. Akhtar, J. Dabrowski, M. Lisker, Y. Yamamoto, A. Mai, Ch. Wenger, M. Lukosius
ACS Applied Materials & Interfaces 12(2), 3188 (2020)
DOI: 10.1021/acsami.9b18448, (Graphen)
The oxidation behavior of Ge(001) and Ge(110) surfaces underneath the CVD grown graphene films has been investigated experimentally and interpreted on the basis of ab initio calculations. Freshly grown samples were exposed to air for more than seven months and periodically monitored by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. The oxidation of Ge(110) started with incubation time of several days, during which the oxidation rate was supposedly exponential. After an ultrathin oxide grew, the oxidation continued with a slow but constant rate. No incubation was detected for Ge(001). The oxide thickness was initially proportional to the square root of time. After two weeks the rate saturated at a value fourfold higher than that for Ge(110). We argue that after the initial phase, the oxidation is limited by the diffusion of oxidizing species through atomic-size openings at graphene domain boundaries and is influenced by the areal density and by the structural quality of the boundaries, whereby the latter determines the initial behavior. Prolonged exposure affected the surface topography and reduced the compressive strain in graphene, from ~ –0.15% to ~ 0.0% on Ge(001) and from ~ –1% to ~ –0.5% on Ge(110). In the last step, both the air-exposed samples were annealed in vacuum at 850⁰C. After annealing, the oxidation of Ge substrates through graphene was reversed by removing the oxygen atoms and thus restoring the original status of graphene/Ge systems. These findings might constitute an important step towards further optimization of graphene/Ge systems.

(4) Comparison of Three Monolithically Integrated TIA Topologies for 50 Gb/s OOK and PAM4
H. Andrade, A. Maharry, T. Hirokawa, L. Valenzuela, St. Simon, C.L. Schow, J.F. Buckwalter
Proc. SPIE Optical Interconnects XX (2020), 11286, 112860W (2020)

(5) Highly Sensitive Capacitive Sensor Based on Injection Locked Oscillators with ppm Sensing Resolution
M. Babay, C. Hallepee, C. Dalmay, B. Barelaud, E. Durmaz, C. Baristiran Kaynak, M. Kaynak, D. Cordeau, A. Pothier
Proc. IEEE MTT-S International Microwave Symposium (IMS 2020), 456 (2020)
(SUMCASTEC)

(6) Characterization and Tests of Different Mach-Zehnder Silicon Photonic Modulator Configurations
D. Badoni, V. Bonaiuto, M. Casalboni, F. De Matteis, G. Di Giuseppe, L. Frontini, R. Gunnella, V. Liberali, A. Mai, G. Paoluzzi, P. Prosposito, A. Salamon, G. Salina, F. Sargeni, S. Schrader, A. Stabile, P. Steglich
Materials Research Proceedings 16, 1 (2020)
DOI: 10.21741/9781644900710-1

(7) Thermo-Mechanical Modeling and Experimental Validation of an Uncooled Microbolometer
C. Baristiran Kaynak, A. Göritz, E.C. Durmaz, M. Wietstruck, E. Onat, A.S. Ozcan, E.R. Turkoglu, Y. Gurbuz, M. Kaynak
Proc. 20th IEEE Topical Meetings on Silicon Monolithic Integrated Circuits in RF Systems (SiRF 2020), 57 (2020)
(IHP-Sabanci Joint Lab)

(8) Contactless Device Characterization of Transistor Structures in Silicon using Electro Optical Frequency Mapping (EOFM)
A. Beyreuther, N. Herfurth, E. Amini, T. Nakamura, G.G. Fischer, S. Keil, C. Boit
Microelectronics Reliability 106, 113583 (2020)
Electro-optical frequency mapping (EOFM) is sensitive to carrier densities in electronic devices. Here, parametric measurements of FET and bipolar transistor structures have been performed with EOFM. The Metal-Insulator-Semiconductor (MIS) system of the FET could be characterized for strong inversion and accumulation for estimations of flatband and threshold voltage. Driving the MIS into accumulation also turns on the source/drain pn junctions into forward bias. The carrier profile of the corresponding parasitic bipolar structure is also measured with EOFM showing the different operation modes of a parasitic bipolar junction transistor and the limited performance of the unwanted bipolar parasitic under the FET. For comparison, EOFM results for a vertical high-performance heterojunction bipolar transistors (HBT) in SiGe:C BiCMOS technology are included, showing clearly distinguishable results of a golden and a faulty SiGe:C HBT.

(9) A Switchless SiGe BiCMOS Bidirectional Amplifier for Wideband Radar Applications
C. Caliskan, M. Yazici, M. Kaynak, Y. Gurbuz
IEEE Transactions on Circuits and Systems II 1 (2019)
DOI: 10.1109/TCSII.2019.2945862
This paper presents a switchless bidirectional amplifier (BDA) with 7-to-30 GHz of bandwidth (BW) and 11.2 dB of peak gain. Common impedance matching networks (IMN) are utilized for both directions, to form a low power and compact amplification stage. It achieves + 0.58 dB/BW of a gain slope, which reaches its peak value at 21 GHz. Its output-referred 1-dB compression point (OP1dB) and group delay (GD) are measured as -2.5 dBm and 41 psec. while having ± 1.5 dB and ± 9.1 psec. variation over the defined BW. Moreover, the BDA dissipates 14 mW of power in 0.42 mm2 of area (including pads). The measurement results demonstrate that the BDA is compatible with the wideband transceiver systems. To the best of the authors’ knowledge, the presented design has the best operating bandwidth with a positively sloped gain without sacrificing from the area, power consumption and other remaining RF features such as noise figure (NF).

(10) Advanced Thermal Modeling of IC – Package Interaction
Z. Cao, M. Stocchi, M. Wietstruck, F. Garbuglia, D. Pincini, M. Kaynak
Proc. IEEE Radio and Wireless Symposium (RWS 2020), 326 (2020)

(11) An Approach to Verify Electro-Thermal Material Stack-Up File Based on Modeling of Poly Resistors with Different Geometry
A. Datsuk, M. Kaynak, A. Balashov, W. Wichmann, F. Vater, V. Timoshenkov
Proc. IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus 2020), 2123 (2020)
DOI: 10.1109/EIConRus49466.2020.9038937, (Design Kit)

(12) Scalable 60 GHz FMCW Frequency-Division Multiplexing MIMO Radar
H. Forstén, T. Kiuru, M. Hirvonen, M. Varonen, M. Kaynak
IEEE Transactions on Microwave Theory and Techniques 68(7), 2845 (2020)
DOI: 10.1109/TMTT.2020.2980521
In this article, a 60-GHz frequency-modulated continuous-wave (FMCW) multiple-input multiple-output (MIMO) radar system using frequency-division multiplexing for TX signal separation is presented. Four-channel transmitter and receiver chips were designed using 130 nm SiGe process. The total number of TX and RX channels can be scaled by the number of chips in the system while still maintaining phase coherence between the channels. 2-D and 3-D object localization measurements are made with four TX and eight RX channel systems. In the 2-D configuration, the radar system is capable of a 5-cm range resolution and 3.5° angular resolution.

(13) Design and Performance Analysis of Integrated Focusing Grating Couplers for the Transverse-Magnetic TM00 Mode in a Photonic BiCMOS Technology
G. Georgieva, K. Voigt, A. Peczek, Ch. Mai, L. Zimmermann
Journal of the European Optical Society-Rapid Publications 16, 7 (2020)
DOI: 10.1186/s41476-020-00129-4
Focusing grating couplers for the excitation of the fundamental transverse-magnetic (TM) mode in integrated silicon photonic waveguides are designed and characterized under the boundary conditions of a photonic BiCMOS foundry. Two types of waveguide geometries are considered – a nanowire and a rib waveguide. Wafer-scale experimental results for nanowire TM grating couplers are in excellent agreement with numerical investigations and demonstrate a robust behavior on the wafer. The mean coupling loss and the 3σ interval are -3.9 ± 0.3 dB. The on wafer variation is three times lower than for the fundamental transverse-electric (TE) polarization. Similarly, the coupling in rib waveguides is examined as well. The results indicate that the rib waveguides require a modified geometry when designed for TM. In general, the nanowire waveguide type is more suitable for TM coupling, showing a stable and repeatable performance.

(14) Cross-Polarization Effects in Sheared 2D Grating Couplers in a Photonic BiCMOS Technology
G Georgieva, K. Voigt, Ch. Mai, P.M. Seiler, K. Petermann, L. Zimmermann
Japanese Journal of Applied Physics 59(SO), SOOB03 (2020)
DOI: 10.35848/1347-4065/ab8e21, (PEARLS)
We investigate numerically and experimentally sheared 2D grating couplers in a photonic BiCMOS technology with a focus on their splitting behavior. Two realization forms of a waveguide-to-grating shear angle are considered. The cross-polarization used as a figure-of-merit is shown to be strongly dependent on the grating perturbation strength and is a crucial limitation not only for the grating splitting performance, but also for its coupling efficiency.

(15) Effective Reduction of the Programing Pulse Width in Al:HfO2-based RRAM Arrays
O. Gonzalez Osorio, E. Perez, S. Dueñas, H. Castan, H. Garcia, Ch. Wenger
Proc. Joint International EUROSOI Workshop and International Conference on Ultimate Integration on Silicon (EUROSOI-ULIS 2019), (2020)
DOI: 10.1109/EUROSOI-ULIS45800.2019.9041880, (NeuroMem)

(16) Development of the Thin TOF-PET Scanner based on Fast Monolithic Silicon Pixel Sensors
D. Hayakawa, G. Iacobucci, L. Paolozzi, P. Valerio, E. Ripiccini, M. Benoit, D. Ferrere, O. Ratib, M. Weber, D. Forshaw, A. Miucchi, Y. Bandi, R. Cardarelli, H. Rücker, M. Kaynak
Nuclear Instruments and Methods in Physics Research Section A 958, 162433 (2020)
DOI: 10.1016/j.nima.2019.162433
The Thin-TOF PET (TT-PET) project aims at the construction of a small-animal PET scanner based on silicon monolithic pixel sensors with 30 ps time resolution for 511 keV photons, equivalent to 100 ps time resolution for minimum ionizing particles. Iterative image reconstruction on Monte-Carlo simulation shows that the scanner can produce high signal-to-noise ratio images with good spatial resolution throughout the whole field of view. The demonstrator chip, comprising a 3 × 10 pixel matrix and a 50 ps binning TDC, was tested at the CERN SPS beam test facility. The demonstrator shows an efficiency greater than 99.9% and a time resolution for minimum ionizing particles of approximately 110 ps.

(17) Influence of Specific Forming Algorithms on the Device-to-Device Variability of Memristive Al-Doped HfO2 Arrays
M.K. Mahadevaiah, E. Perez, Ch. Wenger
Journal of Vacuum Science and Technology B 38(1), 013201 (2020)
DOI: 10.1116/1.5126936, (NeuroMem)
In this work, the influence of specific switching algorithms on device-to-device (D2D) variability of the forming process, in an integrated Al-doped HfO2 1T-1R 4 kbit RRAM array is investigated. The resistive devices are programmed by using two different algorithms: the incremental step pulse and verify algorithm (ISPVA) at different temperatures and the constant amplitude pulse and verify algorithm (CAPVA) at different voltage amplitudes. The stabilized forming currents of both algorithms are compared in terms of their distributions, yields and dispersions. The D2D distributions of the forming voltages of ISPVA and the forming times of CAPVA are fitted by Weibull distributions. The obtained Weibull parameters provide a link with the statistics governing the process. Finally, we discuss the importance of the ISPVA, CAPVA, temperature and voltage amplitudes to improve the reliability of the forming process.

(18) Temperature Dependence of Strain–Phonon Coefficient in Epitaxial Ge/Si(001): A Comprehensive Analysis
C.L. Manganelli, M. Virgilio, O. Skibitzki, M. Salvalaglio, D. Spirito, P. Zaumseil, Y. Yamamoto, M. Montanari, W.M. Klesse, G. Capellini
Journal of Raman Spectroscopy 51(6), 989 (2020)
We investigate the temperature dependence of the Ge Raman mode strain–phonon coefficient in Ge/Si heteroepitaxial layers. By analyzing the temperature‐dependent evolution of both the Raman Ge─Ge line and of the Ge lattice strain, we obtain a linear dependence of the strain–phonon coefficient as a function of temperature. Our findings provide an efficient method for capturing the temperature‐dependent strain relaxation mechanism in heteroepitaxial systems. Furthermore, we show that the rather large variability reported in the literature for the strain–phonon coefficient values might be due to the local heating of the sample due to the excitation laser used in μ‐Raman experiments.

(19) A Physical and Versatile Aging Compact Model for Hot Carrier Degradation in SiGe HBTs under Dynamic Operating Conditions
C. Mukherjee, F. Marc, M. Couret, G.G. Fischer, M. Jaoul, D. Celi, K. Aufinger, T. Zimmer, C. Maneux
Solid-State Electronics 163, 107635 (2020)
DOI: 10.1016/j.sse.2019.107635, (SIGEREL)
This paper presents a new physics-based compact model implementation for interface state creation due to hot-carrier degradation in advanced SiGe HBTs. This model accounts for dynamic stress bias conditions through a combination of the solution of reaction-diffusion theory and Fick’s law of diffusion. The model reflects transistor degradation in terms of base recombination current parameters of HiCuM compact model and its accuracy has been validated against results from long-term aging tests performed close to the safe-operating-areas of various HBT technologies.

(20) A Physical and Versatile Aging Compact Model for Hot Carrier Degradation in SiGe HBTs under Dynamic Operating Conditions
C. Mukherjee, F. Marc, M. Couret, G.G. Fischer, M. Jaoul, D. Celi, K. Aufinger, T. Zimmer, C. Maneux
Solid-State Electronics 163, 107635 (2020)
DOI: 10.1016/j.sse.2019.107635, (Taranto)
This paper presents a new physics-based compact model implementation for interface state creation due to hot-carrier degradation in advanced SiGe HBTs. This model accounts for dynamic stress bias conditions through a combination of the solution of reaction-diffusion theory and Fick’s law of diffusion. The model reflects transistor degradation in terms of base recombination current parameters of HiCuM compact model and its accuracy has been validated against results from long-term aging tests performed close to the safe-operating-areas of various HBT technologies.

(21) Recognition of Objects in the Urban Environment using R-CNN and YOLO Deep Learning Algorithms
R. Saric, M. Ulbricht, M. Krstic, J. Kevric, D. Jokic
Proc. 8th International Conference on Cyber-Physical Systems and Internet-of-Things (CPS & IoT 2020), 455 (2020)
(EMPHASE)

(22) Ge(Sn) Nano-Island Photodetectors with Plasmonic Antennas
V. Schlykow, C.L. Manganelli, F. Römer, C. Clausen, L. Augel, J. Schulze, J. Katzer, M.A. Schubert, B. Witzigmann, T. Schroeder, G. Capellini, I.A. Fischer
Nanotechnology 31(34), 345203 (2020)
We report on photodetection in deep subwavelength Ge(Sn) nano-islands on Si nano-pillar substrates, in which self-aligned nano-antennas in the Al contact metal are used to enhance light absorption by means of local surface plasmon resonances. The impact of parameters such as substrate doping and device geometry on the measured responsivities are investigated and our experimental results are supported by simulations of the three-dimensional distribution of the electromagnetic fields. Comparatively high optical responsivities of about 0.1 A W−1 are observed as a consequence of the excitation of localized surface plasmons, making our nano-island photodetectors interesting for applications in which size reduction is essential.

(23) VCSEL-Based Silicon Photonic Interconnect Technologies
P. Seiler, B. Tillack, L. Zimmermann
Semiconductor Nanophotonics, 1st Edition, Editor: M. Kneissl, A. Knorr, S. Reitzenstein, A. Hoffmann, Chapter 11. VCSEL-Based Silicon Photonic Interconnect Technologies, Springer, 427 (2020)
DOI: 10.1007/978-3-030-35656-9_11, (DFG SFB-787)

(24) Electric Field-Induced Linear Electro-Optic Effect Observed in Silicon-Organic Hybrid Ring Resonator
P. Steglich, C. Villringer, B. Dietzel, Ch. Mai, S. Schrader, M. Casalboni, A. Mai
IEEE Photonics Technology Letters 32(9), 526 (2020)
DOI: 10.1109/JPHOT.2019.2917665, (HOPBIT)
In this work, we report on the observation of the electric field-induced linear electro-optical effect in a silicon-based slot waveguide ring resonator covered by the nonlinear optical polymer Poly[(methyl methacrylate)-co-(Disperse Red 1 methacrylate)]. The device is fabricated in a photonic integrated circuit technology and intensity modulation is demonstrated to work in a direct-detection setup. As unique feature, the electric field-induced linear electro-optical effect allows to modulate the optical carrier wave with a time-varying electric field, while a static electric field can control its amplitude with no need for additional photonic components. Here, a linear tuning of the modulation-amplitude as function of the applied static electric field is demonstrated. This work paves a way toward novel integrated photonic device concepts.

(25) Direct Observation and Simultaneous Use of Linear and Quadratic Electro-Optical Effects
P. Steglich, Ch. Mai, C. Villringer, A. Mai
Journal of Physics D: Applied Physics 53(12), 125106 (2020)
DOI: 10.1088/1361-6463/ab6059, (HOPBIT)
We report on the direct observation and simultaneous use of the linear and quadratic electro-optical effect and propose a method by which higher-order susceptibilities of electro-optical materials can be determined. The evaluation is based on the separation of the second- and third-order susceptibilities and the experimental technique uses a slot waveguide ring resonator fabricated in integrated photonic circuit technology, which is embedded by a guest-host polymer system consisting of the azobenzene dye Disperse Red 1 in a poly(methyl methacrylate) matrix as an active electro-optical material. The contribution of both effects on the electro-optical response under the influence of static and time-varying electrical fields is investigated. We show that the quadratic electro-optical effect has a significant influence on the overall electro-optical response even with acentric molecular orientated molecules. Our findings have important implications for developing electro-optical devices based on polymer-filled slot waveguides and give rise to advanced photonic circuits.

(26) Full-Wave RF Modeling of a Fan-Out Wafer-Level Packaging Technology Based on Al-Al Wafer Bonding
M. Stocchi, M. Wietstruck, S. Schulze, C. Zhibo, S. Tolunay Wipf, M. Kaynak
Proc. 20th IEEE Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SIRF 2020), 60 (2020)
DOI: 10.1109/SIRF46766.2020.9040180

(27) Carbon Related Hillock Formation and its Impact on the Optoelectronic Properties of GaN/AlGaN Heterostructures Grown on Si(111)
H. Tetzner, P. Sana, W.M. Klesse, G. Capellini, M.A. Schubert, S.B. Thapa, P. Storck, T. Schroeder, M.H. Zoellner
Applied Physics Letters 116(25), 252101 (2020)
DOI: 10.1063/5.0005484, (GaN HEMT)
The integration of GaN on Si as large scale substrate still faces many hurdles. Besides the large difference in lattice constant and the high thermal mismatch existing between GaN and Si, spiral hillock growth phenomena are common problems in the development of thick GaN layers. In this work, hexagonal hillocks were observed on GaN/AlGaN high-electron-mobility transistor heterostructures grown on Si(111) by metal-organic chemical vapor deposition. The presence of these morphological and structural defects is attributed to the presence of localized contamination at the AlN/Si interface. These carbon-based defects cause highly defective regions in the AlN seed layer and propagating through all the AlGaN buffer layers, inducing the formation of V-shaped pits at the lower AlGaN interfaces. In hillock regions of the wafers, Raman spectroscopy indicates disturbed two dimensional electron gas characteristics resulting from GaN/AlGaN interface roughness and a decreased amount of free carriers in the potential well. Energy-Dispersive X-ray spectroscopy reveals Ga accumulation inside the V-pits and in nanopipes below, which is responsible for defective areas in GaN and following increased GaN growth rate resulting in hillock formation. Photoluminescence measurements confirm the presence of Ga-rich material reducing the inherent Gallium vacancy concentration. Here, the reduced amount of Ga-vacancies acting as shallow acceptor suppress the ultra-violet luminescence band from donor-acceptor pair transition.

(28) Electronic-to-Photonic Single-Event Transient Propagation in a Segmented Mach-Zehnder Modulator in a Si/SiGe Integrated Photonics Platform
G.N. Tzintzarov, A. Ildefonso, P.S. Goley, M. Frounchi, D. Nergui, S.G. Rao, J. Teng, J. Campbell, A. Khachatrian, S.P. Buchner, D. McMorrow, J.H. Warner, M. Kaynak, L. Zimmermann, J.D. Cressler
IEEE Transactions on Nuclear Science 67(1), 260 (2020)
DOI: 10.1109/TNS.2019.2945860
The propagation of single-event transients from the electrical to the photonic domain in a segmented Mach-Zehnder modulator was investigated using pulsed-laser measurements and lumerical simulations. Although electrical transients can heavily degrade the input data to the modulator, almost all of the degradation can be suppressed once it is converted into the optical domain. The mitigation of transients is primarily accomplished by increasing V π of each segment, making electrical transients up to 6 V essentially negligible. A “folding” effect of the optical transient is also explained in relation to V π . Two radiation-hardening-by-design (RHBD) approaches are suggested to mitigate transient effects.

(29) Contact Resistance and Mobility in Back-Gate Graphene Transistors
F. Urban, G. Lupina, A. Grillo, N. Martucciello, A. Di Bartolomeo
Nano Express 1(1), 010001 (2020)
DOI: 10.1088/2632-959X/ab7055
The metal-graphene contact resistance is one of the major limiting factors toward the technological exploitation of graphene in electronic devices and sensors. High contact resistance can be detrimental to device performance and spoil the intrinsic great properties of graphene. In this paper, we fabricate back-gate graphene field-effect transistors with different geometries to study the contact and channel resistance as well as the carrier mobility as a function of gate voltage and temperature.We apply the transfer length method and the y-function method showing that the two approaches can complement each other to evaluate the contact resistance and prevent artifacts in the estimation of carrier mobility dependence on the gate-voltage. We find that the gate voltage modulates both the contact and the channel resistance in a similar way but does not change the carrier mobility. We also show that raising the temperature lowers the carrier mobility, has a negligible effect on the contact resistance, and can induce a transition from a semiconducting to a metallic behavior of the graphene sheet resistance, depending on the applied gate voltage. Finally, we show that eliminating the detrimental effects of the contact resistance on the transistor channel current almost doubles the carrier field-effect mobility and that a competitive contact resistance as low as 700 Ω·μm can be achieved by the zig-zag shaping of the Ni contact.

(30) PI-MOCVD Technology of (La, Sr)(Mn, Co)O3: From Epitaxial to Nanostructured Films
M. Vagner, V. Plausinaitiene, R. Lukose, S. Kersulis, M. Talaikis, B. Knasiene, S. Stanionyte, V. Kubilius, K. Motiejuitis, Z. Saltyte, G. Niaura, E. Naujalis, N. Zurauskiene
Surface and Coatings Technology 385, 125287 (2020)
DOI: 10.1016/j.surfcoat.2019.125287
The novel La1-xSrx(Mn1-yCoy)zO3 (LSMCO) films were grown by Pulsed-Injection Metalorganic Chemical Vapor Deposition (PI-MOCVD) technique on different oxide substrates. The structural, transport and magnetic properties of the LSMCO films were investigated in terms of crystal structure, texture, electric and magnetoresistive properties of the films for room temperature applications in magnetic sensing. Additionally, to lattice matching-mismatching approach between the film and the substrate, chemical engineering in form of chemical doping was investigated. A certain Co content (from 0 up to 0.17) was introduced into non-stoichiometric La1-xSrx(Mn1-yCoy)zO3 films (z = 1.15) and revealed that Mn non-stoichiometry as well as Co content, influences the changes of transition from metal to insulator state temperature TMI. For epitaxial films (LSMCO grown on LaAlO3) the transition temperature (TMI) was very close to Curie temperature (Tc – transition from ferromagnetic to paramagnetic state), whereas for nanostructured films (LSMCO on Sapphire and ceramic Al2O3), the transition temperatures were lower in comparison to Tc. It was found, that for all used substrates the transition temperature tends to decrease with the increase of Co-content in the films. The change of magnetoresistance properties with Co-content was observed and revealed highest magnetoresistance values at room temperature for the films with Co-content of ~0.06 up to 2.3 T magnetic field, leading to improved and controlled sensing properties at low magnetic fields.

(31) Nonlinear Optical Characterization of CsPbBr3 Nanocrystals as a Novel Material for the Integration into Electro-Optic Modulators
F. Vitale, F. De Matteis, M. Casalboni, P. Prosposito, P. Steglich, V. Ksianzou, C. Breiler, S. Schrader, B. Paci, A. Generosi
Materials Research Proceedings 16, 27 (2020)
DOI: 10.21741/9781644900710-4

(32) A 1 mW Cryogenic LNA Exploiting Optimized SiGe HBTs to Achieve an Average Noise Temperature of 3.2K from 4–8GHz
W.-T. Wong, H. Mohsen, H. Rücker, J.C. Bardin
Proc. IEEE MTT-S International Microwave Symposium (IMS 2020), 181 (2020)

(33) Large-Scale Fabrication of Submicrometer-Gate-Length MOSFETs With a Trilayer PtSe2 Channel Grown by Molecular Beam Epitaxy
K. Xiong, M. Hilse, L. Li, A. Göritz, M. Lisker, M. Wietstruck, M. Kaynak, R. Engel-Herbert, A. Madjar, J.C.M. Hwang
IEEE Transactions on Electron Devices 67(3), 796 (2020)
DOI: 10.1109/TED.2020.2966434
This article is the first report of MOSFETs fabricated on PtSe2 grown by molecular beam epitaxy. Both material synthesis and device fabrication are done below 450 °C—the thermal budget ofCMOS back-end-of-line processes. The MOSFETs are batch-fabricated by a CMOScompatible process on 200-mm-diameter Si substrates prepared by a state-of-the-art BiCMOS foundry. With three monolayers of PtSe2, an n-type MOSFET exhibits a current ON/OFF ratio of 43 at room temperature, which increases to 1600 at 80 K. These results are among the best of transistors based on synthesized PtSe2. Despite the thin PtSe2 layer, doping by contact bias lowers the contact resistance significantlyand boosts the current capacity and the ON/OFF ratio. Temperature-dependent current-voltage characteristics imply a bandgap of approximately 0.2 eV, which confirms that the semiconductor-semimetal transition of PtSe2 is not as abrupt as originally predicted. Better MOSFET performancecan be expectedby growing even thinnerPtSe2 uniformlyand by thickeningthe PtSe2 in the contact regions.

(34) Ge/SiGe Multiple Quantum Well Fabrication by Reduced-Pressure Chemical Vapor Deposition
Y. Yamamoto, O. Skibitzki, M.A. Schubert, M. Scuderi, F. Reichmann, M.H. Zoellner, M. De Seta, G. Capellini, B. Tillack
Japanese Journal of Applied Physics Pt. 1 59, SGGK 10 (2020)
DOI: 10.7567/1347-4065/ab65d0, (FLASH)
In this paper we deposit structures comprising a stack of 10 periods made of 15-nm-thick Ge multiple quantum wells (MQWs) enclosed in a 15-nm-thick Si0.2Ge0.8 barrier on SiGe virtual substrates (VSs) featuring different Ge content in the 85%–100% range to investigate the influence of heteroepitaxial strain on Si0.2Ge0.8 and Ge growth. With increasing Ge concentration of the VS, the growth rate of Si0.2Ge0.8 in the MQWs increases. Si incorporation into the Si0.2Ge0.8 layer also becomes slightly higher. However, almost no influence of the growth rate is observed for Ge growth in the MQWs. We argue that increased tensile strain promotes the Si reaction at the surface. In the case of Si0.2Ge0.8 growth on Ge, we observe a smeared interface due to Ge segregation during the growth. Furthermore, we observe that the interface width increases with increasing Ge concentration of the VS. We attribute this observation to the increased segregation of Ge driven by increased strain energy accumulated in the Si0.2Ge0.8 layers. We also observe that the MQW layer "filters out" threading dislocations formed in the VS.

(35) A Wide Locking-Range, Low Phase-Noise and High Output Power D-Band SiGe PLL
S. Zeinolabedinzadeh, I. Song, M. Kaynak, J.D. Cressler
Proc. 20th IEEE Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF 2020), 35 (2020)

(36) A Co-Integrated Silicon-Based Electronic-Photonic Wideband, High-Power Signal Source
S. Zeinolabedinzadeh, P. Goley, M. Frounchi, S. Rao, C.G. Bottenfield, S.E. Ralph, M. Kaynak, L. Zimmermann, St. Lischke, Ch. Mai, J.D. Cressler
Proc. Optical Fiber Communications Conference and Exposition (OFC 2020), M2I.2 (2020)
DOI: 10.1364/OFC.2020.M2I.2, (Photonics)

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