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  • Publications 2019

Publications 2019

since January 2019

(1) Ultrafast Carrier Recombination in Highly N-Doped Ge-on-Si Films
J. Allerbeck, A.J. Herbst, Y. Yamamoto, G. Capellini, M. Virgilio, D. Brida
Applied Physics Letters 114(24), 241104 (2019)
DOI: 10.1063/1.5088012, (Ge Laser)

(2) Field-Modulated Graphene/Silicon Schottky Diodes Fabricated in a fully CMOS-Compatible Process Line
C.A. Chavarin, J. Dabrowski, G. Luongo, M. Lisker, A. Jouvray, P. Caban, A. Di Bartolomeo, Ch. Wenger, A. Mai, M. Lukosius
Proc. International Conference Nano-M&D “Properties, Fabrication and Applications of Nano-Materials and Nano-Devices” (Nano-M&D 2019), 63 (2019)
(Graphica)

(3) Control of Electron State Coupling in Asymmetric Ge/GeSi Quantum Wells
C. Ciano, M. Virgilio, M. Montanari, L. Persichetti, L. Di Gaspare, M. Ortolani, L. Baldassarre, M.H. Zoellner, O. Skibitzki, G. Scalari, J. Faist, D.J. Paul, M. Scuderi, G. Nicotra, T. Grange, S. Birner, G. Capellini, M. De Seta
Physical Review Applied 11(1), 014003 (2019)
DOI: 10.1103/PhysRevApplied.11.014003, (FLASH)
Theoretical predictions indicate that the n-type Ge/Si-Ge multi-quantum-well system is the most promising material for the realization of a Si-compatible THz quantum cascade laser operating at room temperature. To advance in this direction, we study, both experimentally and theoretically, asymmetric coupled multi-quantum-well samples based on this material system, that can be considered as the basic building block of a cascade architecture. Extensive structural characterization shows the high material quality of strain-symmetrized structures grown by chemical vapor deposition, down to the ultrathin barrier limit. Moreover, THz absorption spectroscopy measurements supported by theoretical modeling unambiguously demonstrate inter-well coupling and wavefunction tunneling. The agreement between experimental data and simulations allows us to characterize the tunneling barrier parameters and, in turn, achieve highly controlled engineering of the electronic structure in forthcoming unipolar cascade systems based on n-type Ge/Si-Ge multi-quantum-wells.

(4) Room Temperature Operation of N-Type Ge/SiGe Terahertz Quantum Cascade Lasers Predicted by Non-Equilibrium Green’s Functions
T. Grange, D. Stark, G. Scalari, J. Faist, L. Persichetti, L. Di Gaspare, M. De Seta, M. Ortolani, D.J. Paul, G. Capellini, S. Birner, M. Virgilio
Applied Physics Letters 114(11), 111102 (2019)
DOI: 10.1063/1.5082172, (FLASH)

(5) On the Impact of Strained PECVD Oxide Layers on Oxide Precipitation in Silicon
G. Kissinger, D. Kot, M. Lisker, A. Sattler
ECS Journal of Solid State Science and Technology 8(4), N79 (2019)
DOI: 10.1149/2.0141904jss, (Future Silicon Wafers)
PECVD oxide layers with different layer stress ranging from about 1 MPa to 305 MPa were deposited on silicon wafers with similar concentration of interstitial oxygen. After a thermal treatment consisting of rapid thermal annealing (RTA) and furnace annealing 780 °C 3 h + 1000 °C 16 h in nitrogen the profiles of the oxide precipitate density were investigated. Supersaturations of self-interstitials as function of layer stress were determined by adjusting a modelling results to measured depth profiles of bulk microdefects. The self-interstitial supersaturation generated by RTA at 1250 °C and 1175 °C at the silicon/oxide interface is increasing linearly with increasing layer stress. Values for self-interstitial supersaturation determined on deposited oxide layers after RTA at 1250 °C and 1175 °C are very similar to values published for RTO by Sudo et al. An RTA at 1175°C with a PECVD oxide on top of the wafer is a method to effectively suppress oxygen precipitation in silicon wafers. Nucleation anneals carried out at 650 °C for 4 h and 8 h did not show any effect of PECVD oxide layers on oxide precipitate nucleation.

(6) Oxygen Impurities in Crystalline Silicon
G. Kissinger
Handbook of Photovolatic Silicon, 1st Edition, Editor: D. Yang, Oxygen Impurities in Crystalline Silicon, Springer-Verl., 1 (2019)
DOI: 10.1007/978-3-662-52735-1_20-1, (Future Silicon Wafers)

(7) Comparison of Plasma-Enhanced Atomic Layer Deposition AlN Films Prepared with Different Plasma Sources
M. Kot, K. Henkel, F. Naumann, H. Gargouri, L. Lupina, V. Wilker, P. Kus, E. Pozarowska, S. Garain, Z. Rouissi, D. Schmeisser
Journal of Vacuum Science and Technology A 37(2), 020913 (2019)
DOI: 10.1116/1.5079628

(8) Processing and Integration of Graphene in a 200 mm Wafer Si Technology Environment
M. Lisker, M. Lukosius, M. Fraschke, J. Kitzmann, J. Dabrowski, O. Fursenko, P. Kulse, K. Schulz, A. Krüger, J. Drews, S. Schulze, D. Wolansky, A.M. Schubert, J. Katzer, D. Stolarek, I. Costina, A. Wolff, G. Dziallas, F. Coccetti, A. Mai
Microelectronic Engineering 205, 44 (2019)
DOI: 10.1016/j.mee.2018.11.007, (Graphen)
We present insights into processes of cleaning, patterning, encapsulation, and contacting graphene in a 200mm wafer pilot line routinely used for the fabrication of integrated circuits in Si technologies. We demonstrate key process steps and discuss challenges and roadblocks which need to be overcome to enable integration of this material with Si technologies.

(9) Understanding Temperature Impact on Filament-Related HfO2 Solid-State Incandescent Lighting Emission Devices and Performance Enhancement using Patterned Wafer Approaches
Y. Liu, G. Niu, C. Yang, S. Wu, L. Dai, O. Skibitzki
IEEE Electron Device Letters 40(4), 582 (2019)
DOI: 10.1109/LED.2019.2899878

(10) Graphene Schottky Junction on Pillar Patterned Silicon Substrate
G. Luongo, A. Grillo, F. Giubileo, L. Iemmo, M. Lukosius, C.A. Chavarin, Ch. Wenger, A. Di Bartolomeo
Nanomaterials 9(5), 659 (2019)
DOI: 10.3390/nano9050659, (Graphen)

(11) Analysis of Parasitic Effects in Filamentary-Switching Memristive Memories using an Approximated Verilog-A Memristor Model
N. Lupo, E. Perez, Ch. Wenger, F. Maloberti, E. Bonizzoni
IEEE Transactions on Circuits and Systems I 66(5), 1935 (2019)
DOI: 10.1109/TCSI.2018.2882993

(12) The Role of Substrate Temperature and Magnetic Filtering for DLC by Cathodic Arc Evaporation
H. Lux, M. Edling, M. Lucci, J. Kitzmann, C. Villringer, P. Siemroth, F. De Matteis, S. Schrader
Coatings 9(5), 354 (2019)
DOI: 10.3390/coatings9050345
Diamond-like carbon (DLC) films were deposited using two different types of high current arc evaporation. The first process used a magnetic particle filter to remove droplets from the plasma. For the second process, the samples were put into a metallic cage which was placed directly above the plasma source. For both processes, we varied the substrate temperature from 21 to 350 °C in order to investigate the temperature effect. The samples were characterized using SEM, AFM, XPS, Raman Spectroscopy, Ellipsometry, Photometry, and Nano Indentation in order to compare both methods of deposition and provide a careful characterization of such DLC films. We found that the sp3 content and the hardness can be precisely adjusted by changing the substrate temperature. Furthermore, in the case of unfiltered deposition, the optical constants can be shifted in the direction of higher absorbance in order to produce black and hard carbon coatings.

(13) Reliability of CMOS Integrated Memristive HfO2 Arrays with Respect to Neuromorphic Computing
M.K. Mahadevaiah, E. Perez, Ch. Wenger, F. Zahari, H. Kohlstedt, A. Grossi, C. Zambelli, P. Olivo, M. Ziegler
Proc. IEEE International Reliability Physics Symposium (IRPS 2019), (2019)
DOI: 10.1109/IRPS.2019.8720552, (NeuroMem)

(14) Towards CMOS Integrated Microfluidics using Dielectrophoretic Immobilization
H. Matbaechi Ettehad, R.K. Yadav, S. Guha, Ch. Wenger
Biosensors (MDPI) 9(2), 77 (2019)
DOI: 10.3390/bios9020077, (BioBic)
Dielectrophoresis is a nondestructive and noninvasive method which is favorable for point-of-care medical diagnostic tests. In this work the feasibility of a CMOS integrated microfluidic device for detecting biocells using dielectrophoresis (DEP) technique was investigated by finite element simulation. The proposed detection system is used to immobilize particles on electrodes while flowing through the microfluidic channel based on the dielectrophoretic (DEP) force and sensing them using the same electrode structures. CMOS compatible interdigitated capacitor (IDC) arrays have been placed into the silicon microfluidic channel. In order to produce the dielectrophoretic force, a fixed frequency voltage small-signal within the range of 1 to maximum 5 V (peak-to-peak) is applied to the IDC. Generation of particles within the microfluidic channel were simulated with COMSOL Multiphysics. COMSOL simulations allowed IDC arrays to be optimized with respect to different cell sizes. Accordingly, in order to have a microsystem platform to be used for different size cells, effective internal and external properties such as geometrical parameters of IDC, voltage, frequency and fluid flow velocity were characterized.

(15) The Electronic Structure of ε-Ga2O3
M. Mulazzi, F. Reichmann, A. Becker, W.M. Klesse, P. Alippi, V. Fiorentini, A. Parisini, M. Bosi, R. Fornari
Applied Physics Letters Materials 7(2), 022522 (2019)
DOI: 10.1063/1.5054395
The electronic structure of ε-Ga2O3 thin films has been investigated by ab initio calculations and photoemission spectroscopy with UV, soft and hard X-rays to probe the surface and bulk properties. The latter measurements reveal a peculiar satellite structure in the Ga 2p core level spectrum, absent at the surface, and a core-level broadening that can be attributed to photoelectron recoil. The photoemission experiments indicate that the energy separation between valence band and Fermi level is about 4.4 eV, a valence band maximum (VBM) at the Г point and an effective mass of the highest lying bands of - 4.2 free electron masses. The value of the band gap compares well with that obtained by optical experiments and with calculations done using a hybrid density-functional, which also reproduce well the dispersion and density of states.

(16) Advanced Coherent X-Ray Diffraction and Electron Microscopy of Individual InP Nanocrystals on Si Nanotips for III-V-on-Si Electronics and Optoelectronics
G. Niu, S.J. Leake, O. Skibitzki, T. Niermann, J. Carnis, F. Kießling, F. Hatami, E.H. Hussein, M.A. Schubert, P. Zaumseil, G. Capellini, W.T. Masselink, W. Ren, Z.-G. Ye, M. Lehmann, T. Schülli, T. Schroeder, M.-I. Richard
Physical Review Applied 11(6), 064046 (2019)
DOI: 10.1103/PhysRevApplied.11.064046

(17) Operando Diagnostic Detection of Interfacial Oxygen “Breathing” of Resistive Random Access Memory by Bulk-Sensitive Hard X-Ray Photoelectron Spectroscopy
G. Niu, P. Calka, P. Huang, S.U. Sharath, S. Petzold, A. Gloskovskii, K. Fröhlich, Y. Zhao, J. Kang, M.A. Schubert, F. Bärwolf, W. Ren, Z.-G. Ye, E. Perez, Ch. Wenger, L. Alff, T. Schoeder
Materials Research Letters 7(3), 117 (2019)
DOI: 10.1080/21663831.2018.1561535

(18) Analysis of the Statistics of Device-to-Device and Cycle-to-Cycle Variability in TiN/Ti/Al:HfO2/TiN RRAMs
E. Perez, D. Maldonado, C. Acal, J.E. Ruiz-Castro, F.J. Alonso, A.M. Aguilera, F. Jimenez-Molinos, Ch. Wenger, J.B. Roldan
Microelectronic Engineering 214, 104 (2019)
DOI: 10.1016/j.mee.2019.05.004, (NeuroMem)
In order to study the device-to-device and cycle-to-cycle variability of switching voltages in 4-kbit RRAM arrays, an alternative statistical approach has been adopted by using experimental data collected from a batch of 128 devices switched along 200 cycles. The statistical distributions of switching voltages have been usually studied by using the Weibull distribution. However, this distribution does not work accurately on Al:HfO2-based RRAM devices. Therefore, an alternative approach based on phase-type distributions is proposed to model the forming, reset and set voltage distributions. Experimental results show that in general the phase-type analysis works better than the Weibull one.

(19) Characterization of the Interface-Driven 1st Reset Operation in HfO2-based 1T1R RRAM Devices
E. Perez, M.K. Mahadevaiah, C. Zambelli, P. Olivo, Ch. Wenger
Solid State Electronics 159, 51 (2019)
DOI: 10.1016/j.sse.2019.03.054, (NeuroMem)
In this work, the increase on the lament conductivity during the 1st Reset operation, by using the incremental step pulse with verify algorithm, is investigated in HfO2-based 1T1R RRAM devices. A new approach is proposed in order to explain the increase of conductivity by highlighting the crucial roles played by both metal-oxide interfaces. The top metal-oxide interface (HfO2-x/TixOy) plays a role in the forming operation by creating a strong gradient of oxygen vacancies in the hafnium oxide layer. The bottom metal-oxide interface (TixOyNz/HfO2-x) also creates oxygen vacancies, which strengthen the conductive lament tip near to this interface at the beginning of the 1st Reset, leading to the reported conductivity increase. After the 1st Reset operation the conductive lament stabilizes at the bottom interface suppressing this behavior in the subsequent reset operations. By modifying the programming parameters and the temperature, it was con rmed a constant current increase of about 9 μA during the 1st Reset regardless the operation conditions imposed.

(20) Gradual Reset and Set Characteristics in Yttrium Oxide based Resistive Random Access Memory
S. Petzold, E. Piros, S.U. Sharath, A. Zintler, E. Hildebrandt, L. Molina-Luna, Ch. Wenger, L. Alff
Semiconductor Science and Technology 34(7), 075008 (2019)
DOI: 10.1088/1361-6641/ab220f, (NeuroMem)

(21) A Modeling Methodology for Resistive RAM based on Stanford-PKU Model with Extended Multilevel Capability
J. Reuben, D. Fey, Ch. Wenger
IEEE Transactions on Nanotechnology 18, 647 (2019)
DOI: 10.1109/TNANO.2019.2922838, (NeuroMem)

(22) Shallow and Undoped Germanium Quantum Wells: A Playground for Spin and Hybrid Quantum Technology
A. Sammak, D. Sabbagh, N.W. Hendrickx, M. Lodari, B.P. Wuetz, A. Tosato, L. Yeoh, M. Bollani, M. Virgilio, M.A. Schubert, P. Zaumseil, G. Capellini, M. Veldhorst, G. Scappucci
Advanced Functional Materials 29(14), 1807613 (2019)
DOI: 10.1002/adfm.201807613

(23) Mid-Infrared Optical Characterization of thin SiNx Membranes
M. Stocchi, D. Mencarelli, L. Pierantoni, D. Kot, M. Lisker, A. Göritz, C. Baristiran Kaynak, M. Wietstruck, M. Kaynak
Applied Optics 58(19), 5233 (2019)
(IHP-Sabanci Joint Lab)
The investigation of the optical constants (e.g. the refractive index n and the extinction coeffcient k) has been performed in the Mid-InfraRed (MIR) spectrum for various Silicon Nitride (SiNx) con gurations. By exploiting the Transfer Matrix Method (TMM) formulation, photometric measurements of transmission and reflection have been used for iteratively calculating the optical parameters of interest. For ensuring the reliability of the latter, the same material from which these parameters were extracted from was deposited for three different thicknesses, e.g. 600, 200 and 100 nm. While the former is optically characterized, the remaining two are used for testing purposes. For each experimental/calculated comparison, the average (made over the whole considered spectrum interval) of the relative error never exceeds 1.5%, which ensures the correctness of the given n and k. For the sake of completeness, a detailed analysis of the intrinsic limitations arising from the very nature of the method will also be conducted.

(24) Demonstration of a Graphene-Base Heterojunction Transistor with Saturated Output Current
C. Strobel, C.A. Chavarin, B. Leszczynska, S. Leszczynski, F. Winkler, S. Killge, S. Völkel, K. Richter, A. Hiess, M. Knaut, J. Reif, M. Albert, Ch. Wenger, J.W. Bartha
Journal of Applied Physics 125(23), 234501 (2019)
DOI: 10.1063/1.5093167, (FFLEXCOM (D020))
A novel transistor with a graphene base embedded between two n-type silicon emitter and collector layers (graphene-base heterojunction transistor) is fabricated and characterized electrically. The base-voltage controlled current of the device flows vertically from the emitter via graphene to the collector. Due to the extremely short transit time for electrons passing the ultimately thin graphene base, the device has a large potential for high-frequency RF applications. The transistor exhibits saturated output currents and a clear modulation of the collector current by means of the graphene base voltage. The vertical transfer current from the emitter via the graphene base to the collector is much lower than expected from device simulations. A comparison of the graphene-base transistor and a reference silicon n‑p‑n bipolar transistor is performed with respect to the main DC transistor characteristics. A common-emitter gain of larger than one has been achieved for the reference device while the graphene-base transistor so far exhibits a much lower gain.

(25) Integrated Reconfigurable Silicon Photonics Switch Matrix in IRIS Project: Technological Achievements and Experimental Results
F. Testa, S. Tondini, F. Gambini, P. Velha, A. Bianchi, C. Kopp, M. Hofbauer, C.L. Manganelli, N. Zecevic, S. Faralli, G. Pares, R. Enne, A. Serrano, B. Goll, G. Fontana, A. Chalyan, J.-M. Lee, P. Pintus, G. Chiaretti, H. Zimmermann, L. Pavesi, C.J. Oton, S. Stracca
IEEE Journal of Lightwave Technology 37(2), 245 (2019)
DOI: 10.1109/JLT.2018.2871974

(26) Inherent Stochastic Learning in CMOS Integrated HfO2 Arrays for Neuromorphic Computing
Ch. Wenger, F. Zahari, M.K. Mahadevaiah, E. Perez, I. Beckers, H. Kohlstedt, M. Ziegler
IEEE Electron Device Letters 40(4), 639 (2019)
DOI: 10.1109/LED.2019.2900867, (NeuroMem)

(27) Development of a Portable Dielectric Biosensor for Rapid Detection of Viscosity Variations and Its In-Vitro Evaluations using Saliva Samples of COPD Patients and Healthy Control
P.S. Zarrin, F.I. Jamal, N. Roeckendorf, Ch. Wenger
Healthcare (MDPI) 7(1), 11 (2019)
DOI: 10.3390/healthcare7010011, (EXASENS)
Chronic Obstructive Pulmonary Disease (COPD) is a life-threatening lung disease affecting millions of people worldwide. Although majority of patients with objective COPD go undiagnosed until late stages of their disease, recent studies suggest that the regular screening of sputum viscosity could provide important information on the disease detection. Since the viscosity of sputum is mainly defined by its mucin-protein and water contents, dielectric biosensors can be used for detection of viscosity variations by screening changes in sputum's contents. Therefore, the objective of this work was to develop a portable dielectric biosensor for rapid detection of viscosity changes and to evaluate its clinical performance in characterizing viscosity differences of saliva samples collected from COPD patients and Healthy Control (HC). For this purpose, a portable dielectric biosensor, capable of providing real-time measurements, was developed. The sensor performance for dielectric characterization of mediums with high water contents, such as saliva, was evaluated using isopropanol-water mixtures. Subsequently, saliva samples, collected from COPD patients and HC, were investigated for clinical assessments. The radio frequency biosensor provided high repeatability of 1.1% throughout experiments. High repeatability, ease of cleaning, low-cost, and portability of the biosensor made it a suitable technology for point-of-care applications.

(28) Correlation of Optical, Structural and Compositional Properties with V-Pit Distribution in InGaN/GaN Multiquantum Wells
M.H. Zoellner, G.A. Chahine, L. Lahourcade, Ch. Mounir, C.L. Manganelli, T.U. Schülli, U.T. Schwarz, R. Zeisel, T. Schroeder
ACS Applied Materials & Interfaces 11(25), 22834 (2019)
DOI: 10.1021/acsami.9b04431
InGaN/GaN double heterostructures and multi-quantum wells have been successfully developed since more than 20 years for LED lightning applications. Recent developments show that state-of-the-art LEDs benefit from artificially generated V-pit defects. However, the control of structural and chemical properties plays a tremendous role. In this paper we report on the lateral distribution of V-pit defects and photoluminescence of InGaN/GaN multi quantum wells grown on thick GaN on patterned sapphire substrates. The synchrotron based scanning x-ray diffraction microscopy technique K-Map was employed to locally correlate these properties with the local tilt, strain and composition of the InGaN/GaN multi quantum well. Compositional fluctuation is the main factor for the variation of photoluminescence intensity and broadening. In turn V-pit defects, align along small-angle grain boundaries, and their strain fields are identified as reason for promoting the InGaN segregation process on a microscale.

The building and the infrastructure of the IHP were funded by the European Regional Development Fund of the European Union, funds of the Federal Government and also funds of the Federal State of Brandenburg.