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  • Publikationen 2018

Publikationen 2018

seit Januar 2018

(1) Electrical Characterization of 3-nm-thin Al2O3 Films Grown by Atomic Layer Deposition for Graphene Base Transistors
M. Albert, M. Junige, J.W. Bartha, Ch. Wenger
Proc. 20th Workshop on Dielectrics in Microelectronics (WODIM 2018), 117 (2018)
(DFG-Graphen)

(2) Pixel Resistance Optimization of a Si0.5Ge0.5/Si MQWs Thermistor Based on In-Situ B Doping for Microbolometer Applications
C. Baristiran Kaynak, Y. Yamamoto, A. Göritz, F. Korndörfer, P. Zaumseil, P. Kulse, K. Schulz, M. Wietstruck, I. Costina, A. Shafique, Y. Gurbuz, M. Kaynak
Proc. SPIE Defense+Commercial Sensing 10624, 10624E1 (2018)
(IHP-Sabanci Joint Lab)

(3) Si(1-x)Gex/Si MQW Based Uncooled Microbolometer Development and Integration into 130 nm BiCMOS Technology
C. Baristiran Kaynak, Y. Yamamoto, A. Göritz, F. Korndörfer, P. Zaumseil, P. Kulse, K. Schulz, M. Fraschke, St. Marschmeyer, T. Wolansky, M. Wietstruck, A. Shafique, Y. Gurbuz, M. Kaynak
ECS Transactions 86(7), 373 (2018)
(IHP-Sabanci Joint Lab)

(4) High Performance Thermistor Based on Si(1-x)Gex/Si Multi Quantum Wells
C. Baristiran Kaynak, Y. Yamamoto, A. Göritz, F. Korndörfer, P. Zaumseil, P. Kulse, K. Schulz, M. Wietstruck, A. Shafique, Y. Gurbuz, M. Kaynak
IEEE Electron Device Letters 39(5), 753 (2018)
(IHP-Sabanci Joint Lab)
This letter represents a prototype of an intrinsic thermistor based on silicon-germanium/silicon (Si1−xGex/Si) multi quantum wells with varying Ge concentration
in SiGe wells. Experimental results of the thermistor prototype are provided in terms of temperature coefficient of resistance (TCR) and noise constant (K1/f). The prototype
with 50% Ge in SiGe wells exhibited an outstanding TCR of −5.5 %/K accompanied by a K1/f of 5.8 × 10−13 for 25 μm × 25 μm and 3.4 × 10−15 for 200 μm × 200 μm pixel
size, showing the concurrent achievement of a very high TCR and a low 1/f noise performance.

(5) Single Crystalline SiGe/Si MQW Thermistor for Uncooled Microbolometers
C. Baristiran Kaynak, Y. Yamamoto, A. Göritz, P. Zaumseil, P. Kulse, K. Schulz, M. Wietstruck, A. Shafique, Y. Gurbuz, M. Kaynak
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 73 (2018)
(IHP-Sabanci Joint Lab)

(6) Dynamic SIMS, Spectroscopic Ellipsometry and X-Ray Diffractometry Analysis of SiGe HBTs with Ge Grading
F. Bärwolf, O. Fursenko, P. Zaumseil, Y. Yamamoto
Semiconductor Science and Technology 34(1), 014005 (2018)
In this paper, SiGe heterojunction bipolar transistors (HBTs) with Ge concentrations up to 40
atomic percent (at%) and different slopes of Ge gradients are characterized by comparing
dynamic secondary ion mass spectrometry (D-SIMS) and multi-angle spectroscopic ellipsometry
(SE). X-ray diffractometry (XRD) was used as reference. D-SIMS results show that sputter rate
and Ge content calibration have major impact on depth profile measurements of HBTs with
graded SiGe. Strained and relaxed SiGe show differences in Ge content calibration and no
difference in sputter rate calibration. Jiang’s protocol was used for Ge content calibration and
proven to be valid up to ∼50 at% Ge. SE with a combination of 3 angles of incidence (AOIs)
(59, 65, 71°) in comparison with the single AOI (71°) realized in industrial setup for
semiconductor manufacturing environment was analyzed to find a more stable solution for
revealing the thickness of plateau and gradient parts of SiGe base. SE with 71° AOI and rotating
compensator is the best choice for in-line HBT with Ge grading characterization. The
determination of gradient shape continues to be a challenging task for SE, due to high parameter
correlations and the need to use some fixed parameters within the fitting procedure. D-SIMS
remains the favorite for graded profile determination. Results of D-SIMS and SE with fixed
parameters are in good agreement with XRD for HBTs with Ge grading.

(7) SiGe Graded HBT Analysis by DSIMS, Spectroscopic Ellipsometry and X-Ray Diffractometry
F. Bärwolf, O. Fursenko, P. Zaumseil, Y. Yamamoto
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 287 (2018)

(8) Planar Semiconductor THz Antennas using Spoof Plasmons for Surface Sensing
M. Bettenhausen, F. Römer, B. Witzigmann, J. Flesch, J. Piehler, C. You, M. Kazmierczak, S. Guha, G. Capellini, T. Schroeder
Proc. IEEE MTT-S International Microwave Symposium (IMS 2018), 236 (2018)
(DFG Group 4 Plasmonics)

(9) Germanium Plasmon Enhanced Resonators for Label-Free Terahertz Protein Sensing
M. Bettenhausen, F. Römer, B. Witzigmann, J. Flesch, J. Piehler, C. You, M. Kazmierczak, S. Guha, G. Capellini, T. Schroeder
Frequenz: Journal of RF-Engineering and Telecommunications 72(3-4), 113 (2018)
(DFG Group 4 Plasmonics)
A Terahertz protein sensing concept based on subwavelength Ge resonators is presented. Ge bowtie resonators have been designed and characterized with a resonance frequency of 0.5 THz and calculated local intensity enhancement of 10.000. Selective biofunctionalization of Ge resonators on Si wafer was achieved in one step using lipoic acid-HaloTag ligand (LA-HTL) for biofunctionalization and passivation. The results lay the foundation for future investigation of protein tertiary structure and the dynamics of protein hydration shell in response to protein conformation changes.

(10) Gate Stack and Ni(SiGeSn) Metal Contacts Formation on Low Bandgap Strained (Si)Ge(Sn) Semiconductors
D. Buca, C. Schulte-Braucks, N. von den Driesch, A.T. Tiedemann, U. Breuer, J.M. Hartmann, P. Zaumseil, S. Mantl, Q.T. Zhao
Proc. 18th International Workshop on Junction Technology (IWJT 2018), (2018)
(Ge Laser)

(11) Current Modulation of a Heterojunction Structure by an Ultra-Thin Graphene Base Electrode
C.A. Chavarin, C. Strobel, J. Kitzmann, A. Di Bartolomeo, M. Lukosius, M. Albert, J.W. Bartha, Ch. Wenger
Materials 11(3), 345 (2018)
(FFLEXCOM (D020))
Graphene has been proposed as the current controlling element of vertical transport in heterojunction transistors, as it potentially could achieve high operation frequencies due to its metallic character and 2D nature. Simulations of graphene acting as a thermionic barrier between the transport of two semiconductor layers have shown cut-off frequencies larger than 1 THz. Furthermore, the use of n-doped amorphous silicon, (n)-a-Si:H, as the semiconductor for this approach could enable flexible electronics with high cutoff frequencies. In this work, we fabricated a vertical structure on a rigid substrate where graphene is embedded between two differently doped (n)-a-Si:H layers deposited by very high frequency (140 MHz) plasma-enhanced chemical vapor deposition. The operation of this heterojunction structure is investigated by the two diode-like interfaces by means of temperature dependent current-voltage  characterization, followed by the electrical characterization in a three-terminal configuration. We demonstrate that the vertical current between the (n)-a-Si:H layers is successfully controlled by the ultra-thin graphene base voltage. While current saturation is yet to be achieved, a transconductance of ~230 μS was obtained, demonstrating a moderate modulation of the collector-emitter current by the ultra-thin graphene base voltage. These results are a promising progress towards the application of graphene base heterojunction transistors.

(12) A Flexible Approach Towards Silicon-Graphene Heterojunction Transistors
C.A. Chavarin, C. Strobel, J. Kitzmann, M. Lukosius, M. Albert, B. Leszczynska, S.S. Leszczynski, J.W. Bartha, Ch. Wenger
Proc. 48th European Microwave Week (EuMW 2018) - Special session F - FFlexCom, 729 (2018)
(FFLEXCOM (D020))
The graphene-base heterojunction transistor (GBHT) is an attractive device concept to reach THz operation frequencies. The novel transistor consists of two n-doped silicon layers with a graphene monolayer in between. The structure of the device is similar to an n-p-n bipolar transistor with the base being replaced by graphene. In this work, the current state of GBHT development at TU-Dresden/IHP will be presented. First, the innovative non-destructive deposition technology for n-a-Si:H on graphene will be highlighted. Next, the successful control of the graphene/ silicon interfaces is described. Up to now, highly rectifying Schottky diodes (ION/IOFF 104 - 105, +/- 1V) have been achieved for both the BE and BC graphene-silicon interface. Finally, first GBHT prototypes were prepared and analyzed. It is verified, that the vertical current between the (n)-a-Si:H layers is successfully controlled by the ultra-thin graphene base voltage.

(13) Characterization of Fabricated Devices with High Si/Sn Content and N-Doped SiGeSn
C.J. Clausen, I.A. Fischer, M. Oehme, G. Capellini, J. Schulze
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 235 (2018)
(DFG GeSn Laser)

(14) Modeling of Materials for Silicon-Compatible Microelectronics
J. Dabrowski, G. Kissinger, G. Lippert, G. Lupina, M. Lukosius, P. Sana, T. Schroeder
Proc. NIC Symposium (NiC Series) 49, 239 (2018)
(Future Silicon Wafers)
Ab initio density functional theory (DFT) is an established method to model the behavior of materials at the atomic scale. At the IHP, we use it to investigate materials systems that are of interest to the most popular and cost-efficient technology, by which electronics is made today: the silicon technology. Here we report on the results obtained for various materials: (a) for strictly 2D atomic sheets (graphene), (b) for heteroepitaxial layers (oxides and nitrides), their surfaces, and the interfaces between these films, and (c) for bulk crystals (defects in silicon). The graphene sheets are intended as components of chemical sensors, optical modulators, and high-speed and high-power transistors. The chemical reactions and diffusion processes governing the nucleation and growth of graphene on perfect (flat and stepped) and defected surfaces of germanium films were simulated, and the mechanisms responsible for the observed growth modes were elucidated. The Sc oxide and nitride films constitute the topmost part of a heterostructure on which GaN diodes, lasers, and high-power transistors can be assembled. The simulations provided insight into the intermixing of oxygen and nitrogen. The substrate on which all these films and other device structures are grown, is crystalline silicon. For numerous application it is critical that the substrate getters (collects and binds) the impurities that are unintentionally introduced by the technological process. The formation of oxygen precipitates used as the gettering centers is associated with the presence of missing atoms (vacancies) in the Si bulk. We studied the process of vacancy clustering and oxidation, we extrapolated the clustering results to infinite separation between the defects, and we discussed the implications also for the interpretation of deep level transient spectroscopy (DLTS) or for the strategy to perform numerically expensive defect calculations (as done with hybrid potentials), among others.

(15) Modeling of Materials for Silicon-Compatible Microelectronics
J. Dabrowski, G. Kissinger, G. Lippert, G. Lupina, M. Lukosius, P. Sana, T. Schroeder
Proc. NIC Symposium (NiC Series) 49, 239 (2018)
(Siltronic Project)
Ab initio density functional theory (DFT) is an established method to model the behavior of materials at the atomic scale. At the IHP, we use it to investigate materials systems that are of interest to the most popular and cost-efficient technology, by which electronics is made today: the silicon technology. Here we report on the results obtained for various materials: (a) for strictly 2D atomic sheets (graphene), (b) for heteroepitaxial layers (oxides and nitrides), their surfaces, and the interfaces between these films, and (c) for bulk crystals (defects in silicon). The graphene sheets are intended as components of chemical sensors, optical modulators, and high-speed and high-power transistors. The chemical reactions and diffusion processes governing the nucleation and growth of graphene on perfect (flat and stepped) and defected surfaces of germanium films were simulated, and the mechanisms responsible for the observed growth modes were elucidated. The Sc oxide and nitride films constitute the topmost part of a heterostructure on which GaN diodes, lasers, and high-power transistors can be assembled. The simulations provided insight into the intermixing of oxygen and nitrogen. The substrate on which all these films and other device structures are grown, is crystalline silicon. For numerous application it is critical that the substrate getters (collects and binds) the impurities that are unintentionally introduced by the technological process. The formation of oxygen precipitates used as the gettering centers is associated with the presence of missing atoms (vacancies) in the Si bulk. We studied the process of vacancy clustering and oxidation, we extrapolated the clustering results to infinite separation between the defects, and we discussed the implications also for the interpretation of deep level transient spectroscopy (DLTS) or for the strategy to perform numerically expensive defect calculations (as done with hybrid potentials), among others.

(16) Modeling of Materials for Silicon-Compatible Microelectronics
J. Dabrowski, G. Kissinger, G. Lippert, G. Lupina, M. Lukosius, P. Sana, T. Schroeder
Proc. NIC Symposium (NiC Series) 49, 239 (2018)
(Graphen)
Ab initio density functional theory (DFT) is an established method to model the behavior of materials at the atomic scale. At the IHP, we use it to investigate materials systems that are of interest to the most popular and cost-efficient technology, by which electronics is made today: the silicon technology. Here we report on the results obtained for various materials: (a) for strictly 2D atomic sheets (graphene), (b) for heteroepitaxial layers (oxides and nitrides), their surfaces, and the interfaces between these films, and (c) for bulk crystals (defects in silicon). The graphene sheets are intended as components of chemical sensors, optical modulators, and high-speed and high-power transistors. The chemical reactions and diffusion processes governing the nucleation and growth of graphene on perfect (flat and stepped) and defected surfaces of germanium films were simulated, and the mechanisms responsible for the observed growth modes were elucidated. The Sc oxide and nitride films constitute the topmost part of a heterostructure on which GaN diodes, lasers, and high-power transistors can be assembled. The simulations provided insight into the intermixing of oxygen and nitrogen. The substrate on which all these films and other device structures are grown, is crystalline silicon. For numerous application it is critical that the substrate getters (collects and binds) the impurities that are unintentionally introduced by the technological process. The formation of oxygen precipitates used as the gettering centers is associated with the presence of missing atoms (vacancies) in the Si bulk. We studied the process of vacancy clustering and oxidation, we extrapolated the clustering results to infinite separation between the defects, and we discussed the implications also for the interpretation of deep level transient spectroscopy (DLTS) or for the strategy to perform numerically expensive defect calculations (as done with hybrid potentials), among others.

(17) Graphene/Silicon Schottky Diodes for Photodetection
A. Di Bartolomeo, G. Luongo, L. Iemmo, F. Giubileo, G. Niu, G. Lupina, T. Schroeder
Proc. 12th IEEE Nanotechnology Materials and Devices Conference (NMDC 2017), 45 (2018)

(18) Filament Growth and Resistive Switching in Hafnium Oxide Memristive Devices
S. Dirkmann, J. Kaiser, Ch. Wenger, Th. Mussenbrock
ACS Applied Materials & Interfaces 10(17), 14857 (2018)
(NeuroMem)

(19) Field-Driven Hopping Transport of Oxygen Vacancies in Memristive Oxide Switches with Interface-Mediated Resistive Switching
N. Du, N. Manjunath, Y. Li, S. Menzel, E. Linn, R. Waser, T. You, D. Bürger, I. Skorupa, D. Walczyk, C. Walczyk, O.G. Schmidt, H. Schmidt
Physical Review Applied 10(5), 054025 (2018)
(Non-Volatile Memory (NVM))

(20) An Automated Test Equipment for Characterization of Emerging MRAM and RRAM Arrays
A. Grossi, C. Zambelli, P. Olivo, P. Pellati, M. Ramponi, Ch. Wenger, J. Alvarez-Herault, K. Mackay
IEEE Transactions on Emerging Topics in Computing 6(2), 269 (2018)
DOI: 10.1109/TETC.2016.2585043, (R2RAM)
In this paper it is presented a test equipment for the characterization of two different emerging memory technologies like the Thermally Assisted Switching-Magnetic Random Access Memory (TASMRAM) and the Resistive Random Access Memory (RRAM). The instrument is developed to allow a fast characterization of test array structures and can be potentially adapted for any other non-volatile memory generation. The hardware architecture is based on a PCI S5933 chipset being the local bus interface of a x86-PC that communicates with the units of the system like 14 bits/100 MHz arbitrary waveform generators and 12 bits/70 MHz programmable measurement units. A user-friendly software interface developed in LabVIEW has been implemented to allow large flexibility in changing the test parameters and a fast analysis of the test results. The instrument performance has been evaluated performing the typical non-volatile memory tests such as endurance and disturbs characterizations, running test flows up to 320 hours for MRAM devices and
up to 6,137 hours for RRAM devices.

(21) Impact of the Precursor Chemistry and Process Conditions on the Cell-to-Cell Variability in 1T-1R based HfO2 RRAM Devices
A. Grossi, E. Perez, C. Zambelli, P. Olivo, E. Miranda, R. Roelofs, J. Woodruff, P. Raisanen, W. Li, M. Givens, I. Costina, M.A. Schubert, Ch. Wenger
Scientific Reports 8, 11160 (2018)
(Panache)
The Resistive RAM (RRAM) technology is currently in a level of maturity that calls for its integration into CMOS compatible memory arrays. This CMOS integration requires a perfect understanding of the cells performance and reliability in relation to the deposition processes used for their manufacturing. In this paper, the impact of the precursor chemistries and process conditions on the performance of HfO2 based memristive cells is studied. An extensive characterization of HfO2 based 1T1R cells, a comparison of the cell-to-cell variability, and reliability study is performed. The cells’ behaviors during forming, set,
and reset operations are monitored in order to relate their features to conductive filament properties and process-induced variability of the switching parameters. The modeling of the high resistance state (HRS) is performed by applying the Quantum-Point Contact model to assess the link between thedeposition condition and the precursor chemistry with the resulting physical cells characteristics.

(22) Gate-Controlled Quantum Dots and Superconductivity in Planar Germanium
N.W. Hendrickx, D.P. Franke, A. Sammak, M. Kouwenhoven, D. Sabbagh, L. Yeoh, R. Li, M.L.V. Tagliaferri, M. Virgilio, G. Capellini, G. Scappucci, M. Veldhorst
Nature Communications 9, 2835 (2018)
Superconductors and semiconductors are crucial platforms in the field of quantum computing.
They can be combined to hybrids, bringing together physical properties that enable
the discovery of new emergent phenomena and provide novel strategies for quantum control.
The involved semiconductor materials, however, suffer from disorder, hyperfine interactions
or lack of planar technology. Here we realise an approach that overcomes these issues
altogether and integrate gate-defined quantum dots and superconductivity into germanium
heterostructures. In our system, heavy holes with mobilities exceeding 500,000 cm2 (Vs)−1
are confined in shallow quantum wells that are directly contacted by annealed aluminium
leads. We observe proximity-induced superconductivity in the quantum well and demonstrate electric gate-control of the supercurrent. Germanium therefore has great promise for fast and coherent quantum hardware and, being compatible with standard manufacturing, could become a leading material for quantum information processing.

(23) Stable and Selective Self-Assembly of α-Lipoic Acid on Ge(001) Surface for Biomolecule Immobilization
M. Kazmierczak, J. Flesch, J. Mitzloff, G. Capellini, W.M. Klesse, O. Skibitzki, C. You, M. Bettenhausen, B. Witzigmann, J. Piehler, T. Schroeder, S. Guha
Journal of Applied Physics 123, 175305 (2018)
(DFG Group 4 Plasmonics)
In this work, a stable and selective functionalization of germanium (Ge) surface embedded in silicon dioxide (SiO2) is demonstrated. The Ge(001) surface was functionalized using alpha lipoic acid (ALA), which can potentially be utilized for immobilization of a range of biomolecules. A detailed pH-dependence study was carried out to establish the role of the incubation pH in the formation of a well-ordered monolayer of the ALA on the Ge(001) surface. It has been shown that there is a threshold pH of incubation, which splits the examined pH range into two regions; below the threshold pH a disordered multilayer formation of ALA is observed and a stable well-ordered layer formation is observed above this pH, leading to a monolayer at a particular pH value. Further, the stability analysis of the ALA monolayer in ambient conditions revealed that the most stable functionalized Ge sample can effectively resist oxidation for a period of up to seven days. Using the established method, a selective functionalization of exclusively the Ge(001) surface embedded in SiO2 was demonstrated, making a pathway towards future immobilization of biomolecules on the Ge(001) surfaces in Ge based biosensors.

(24) Oxygen in Silicon: End of the Story?
G. Kissinger, D. Kot, M.A. Schubert, J. Dabrowski, A. Sattler, T. Müller
ECS Transactions 86(10), 61 (2018)
(Future Silicon Wafers)
Oxygen in silicon is investigated since decades. Although, the goals of research and development in this field changed over the years it is and it will remain an ongoing topic which is mainly driven by defect and impurity control in crystal growth and device processing. Examples from our own published results about ab initio calculation for understanding of the initial stages of oxygen precipitation, investigation of the stoichiometry of oxygen precipitates, elucidation of the gettering mechanism of Cu at oxygen precipitates, and N-doping for the homogeneous oxygen precipitation during high temperature annealing in wafers optimized with respect to voids will be presented.
 

(25) On the Impact of Deposited Nitride Layers on Oxide Precipitation in Czochralski Silicon
G. Kissinger, D. Kot, T. Grabolla, T. Müller, A. Sattler
Proc. 8th Forum on the Science and Technology of Silicon Materials 2018, 27 (2018)
(Future Silicon Wafers)
We investigated the influence of stress and in-diffused nitrogen on oxide precipitation after rapid thermal annealing (RTA). For this purpose, we used deposited nitride layers in order to focus more on the stress effects than on interface reactions during nitride formation. One-sided and double-sided nitride layers accompanied by simulation models helped to understand the behavior of intrinsic point defects, nitrogen, and strain. It was found that the presence of a nitride layer of any thickness, within the range, which we investigated, in direct contact with the silicon surface is sufficient to markedly change the precipitation behavior of interstitial oxygen after RTA at 1175 °C and 1250 °C. However, a 10 nm oxide between silicon substrate and nitride layer prevents any change of the BMD depth profile. Peaks of in-diffused nitrogen below the silicon surface lead to an enhanced oxygen precipitation only for RTA at 1250 °C but not for RTA at 1175 °C. RTA treatment of silicon wafers with one-sided nitride layers at 1250 °C leads to very sharp and small defect denuded zones in subsequent annealing and would be suitable for proximity gettering with their depths being nearly independent of the thickness of the nitride layer.
 

(26) Dielectrophoretic Immobilisation of Nanoparticles as Isolated Singles in Regular Arrays
X. Knigge, Ch. Wenger, F.F. Bier, R. Hölzl
Journal of Physics D: Applied Physics 51(6), 065308 (2018)
(BioBic)
We demonstrate the immobilisation of polystyrene nanoparticles on vertical nano-electrodes by means of dielectrophoresis. The electrodes have diameters of 500 nm or 50 nm, respectively, and are arranged in arrays of several thousand electrodes, allowing many thousands of experiments in parallel. At a frequency of 15 kHz, which is found favourable for polystyrene, several occupation patterns are observed, and both temporary and permanent immobilisation is achieved. In addition, a histogram method is applied, which allows to determine the number of particles occupying the electrodes. These results are validated with scanning electron microscopy images. Immobilising exactly one particle at each electrode tip is achieved for electrode tip diameters with half the particle size. Extension of this system down to the level of single molecules is envisaged, which will avoid ensemble averaging at still statistically large sample sizes.

(27) Comparison of Experimental and Modeling Results on VOn Formation at Ultra-High Temperature in Silicon
D. Kot, G. Kissinger, J. Dabrowski, A. Sattler
Proc. 8th Forum on the Science and Technology of Silicon Materials 2018, 211 (2018)
(Future Silicon Wafers)

(28) VOn Complexes in RTA Treated Czochralski Silicon Wafers Investigated by FTIR Spectroscopy
D. Kot, G. Kissinger, J. Dabrowski, A. Sattler
ECS Journal of Solid State Science and Technology 7(12), P707 (2018)

(29) VOn Complexes in RTA Treated Czochralski Silicon Wafers Investigated by FTIR Spectroscopy
D. Kot, G. Kissinger, J. Dabrowski, A. Sattler
ECS Transactions 86(10), 95 (2018)
Oxygen-vacancy complexes formed after rapid thermal annealing in silicon wafers were investigated by FTIR spectroscopy at 6K. It was found that V04 is the only
detectable complex. The concentration of V04 complexes increases with increasing temperature of RTA treatrnent in the temperature range between 1250 oc and 1400 °C. The concentration at maximal temperature is equal to 4.5 x 1013 cm-3.  The experimental results were compared with concentrations of VO. complexes in silicon wafers obtained using ab-initio calculations combined with rate equation modelling. The simulated concentration of V04 corresponds weil to the measured   concentration.   The   BMD   density   increases   with increasing  V04  concentration.  The  vacancies   stored  in  vo. complexes after RTA are slowly released during further annealing and enhance oxide precipitation.

(30) Synthese und Technologieentwicklung für graphenbasierte Bauelemente
M. Lisker, M. Lukosius, G. Lupina, J. Kitzmann, A. Wolff, A. Mai
Proc. EFDS-Workshop: Graphen und andere 2D Materialien (2018), (2018)
(Graphen)

(31) Contacting Graphene in a 200 mm Wafer Silicon Technology Environment
M. Lisker, M. Lukosius, J. Kitzmann, M. Fraschke, D. Wolansky, S. Schulze, G. Lupina, A. Mai
Solid State Electronics 144, 17 (2018)
Two different approaches for contacting graphene in a 200mm wafer silicon technology environment were tested. The key is the opportunity to create a thin SiN passivation layer on top of the graphene protecting it from the damage by plasma processes. The first approach uses pure Ni contacts with a thickness of 200 nm. For the second attempt, Ni is used as the contact metal which substitutes the Ti compared to a standard contact hole filling process. Accordingly, the contact hole filling of this “stacked via” approach is Ni/TiN/W. We demonstrate that the second “stacked Via” is beneficial and shows contact resistances of a wafer scale process with values below 200 Ohm μm.

(32) Growth of High-Quality Graphene for Photonics
M. Lukosius, M. Lisker, G. Dziallas, J. Dabrowski, M. Fraschke, G. Lippert, A. Wolff, A. Mai, Ch. Wenger
Proc. 8th Graphene 2018, (2018)
(Graphen)

(33) Electronic Properties of Graphene/p-Silicon Schottky Junction
G. Luongo, A. Di Bartolomeo, F. Giubileo, C.A. Chavarin, Ch. Wenger
Journal of Physics D: Applied Physics 51(25), 255305 (2018)
(DFG-Graphen)
We fabricate graphene/p-Si heterojunctions and characterize their current-voltage properties in a wide temperature range. The devices exhibit Schottky diode behaviour with a modest rectification factor of ~10^2. The Schottky parameters are estimated in the framework of the thermionic emission theory using Cheung’s and Norde’s methods. At room temperature, we obtain an ideality factor of about 2 and a Schottky barrier height of 0.18 eV, which reduces at lower temperatures. We shed light on the physical mechanisms responsible for the low barrier, discussing the p-doping of graphene caused by the transfer process, the exposure to air and the out-diffusion of boron from the Si substrate. We finally propose a band model that fully explains the experimental current-voltage features, included a plateau observed in reverse current at low temperatures.

(34) A Voltage-Time Model for Memristive Devices
N. Lupo, E. Bonizzoni, E. Perez, Ch. Wenger, F. Maloberti
IEEE Transactions on Very Large Scale Integration (VLSI) Systems 26(8), 1452 (2018)
(Panache)
This paper presents a novel electrical model for oxide resistive memories. Starting from some considerations about the physical characteristics of the resistance change in the memory element of these devices, the traditional model based on a resistor series has been improved and extended, solving some limitations pending in the classical interpretation. The low complexity of the proposed model is very profitable for the resistive memory designers as it is easy to be integrated in the traditional design flows. Experimental results for HfO2 devices
implemented in a 250-nm BiCMOS process show an excellent match with the simulations achieved by using the proposed model and validate its effectiveness.

(35) An Approximated Verilog-A Model for Memristive Devices
N. Lupo, E. Bonizzoni, E. Perez, Ch. Wenger, F. Maloberti
Proc. IEEE International Symposium on Circuits and Systems (ISCAS 2018), (2018)
(Panache)

(36) Low-Power-Consumption Integrated Tunable Filters for WDM Switching Applications in Silicon Photonics
C.L. Manganelli, P. Velha, P. Pintus, F. Gambini, O. Lemonnier, L. Adelmini, C. Kopp, S. Faralli, F. Di Pasquale, Ch. Wenger , C.J. Oton
IEEE Photonics Technology Letters 30(18), 1601 (2018)

(37) Efficient On-Chip Tunable Selective Switches for Optical Interconnections
C.L. Manganelli, P. Velha, P. Pintus, F. Gambini, O. Lemonnier, C. Kopp, S. Faralli, F. Di Pasquale, C.J. Oton
Proc. 20th Italian National Conference on Photonic Technologies (Fotonica 2018), (2018)
The experimental results of thermally tunable double microring resonator devices for integrated wavelength division multiplexing applications in Silicon Photonics are presented in this paper. The described devices show a free-spectral range (FSR) up to 2.4 THz (19.2 nm) around 1550 nm and channel rejection higher than 35 dB. Ti/TiN metal heaters allow the record value of power consumption of 20 mW per FSR per ring and symmetric tuning obtained with less than 1% of electrical compensation.

(38) Optical Properties of a N-Doped Ge/SiGe Quantum Wells in the THz Range
M. Montanari, C. Ciano, L. Di Gaspare, D. Sabbagh, M. Virgilio, M. Ortolani, L. Baldassarre, G. Capellini, J. Schmidt, S. Winnerl, M. Helm, G. Scalari, D. Stark, J. Faist, K. Rew, D.J. Paul, T. Grange, S. Birner, M. De Seta
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 137 (2018)
(FLASH)

(39) Photoluminescence Study of Inter-Band Transitions in Few, Pseudomorphic and Strain-Unbalanced Ge-Rich Ge/GeSi Multiple Quantum Wells
M. Montanari, M. Virgilio, C.L. Manganelli, P. Zaumseil, M.H. Zoellner, Y. Hou, M.A. Schubert, L. Persichetti, L. Di Gaspare, M. De Seta, E. Vitiello, F. Pezzoli, G. Capellini
Physical Review B 98(19), 195310 (2018)
(FLASH)
In this paper we investigate the structural and optical properties of few strain-unbalanced multiple Ge/GeSi quantum wells pseudomorphically grown on GeSi reverse-graded substrates. The obtained high epitaxial quality demonstrates that strain symmetrization is not a mandatory requirement for few quantum-well repetitions. Photoluminescence data, supported by a thorough theoretical modeling, allow us to unambiguously disentangle the spectral features of the quantum wells from those originating in the virtual substrate and to evaluate the impact on the optical properties of key parameters, such as quantum confinement, layer compositions, excess carrier density, and lattice strain. This detailed understanding of the radiative recombination processes is of paramount importance for the development of Ge/GeSi-based optical devices.

(40) The Role of the Bottom and Top Interfaces in the 1st Reset Operation in HfO2 based RRAM Devices
E. Perez, M.K. Mahadevaiah, C. Zambelli, P. Olivo, Ch. Wenger
Proc. Joint International EUROSOI Workshop and International Conference on Ultimate Integration on Silicon (EUROSOI-ULIS 2018), (2018)
(NeuroMem)

(41) Data Retention Investigation in HfO2-based RRAM Arrays by using Accelerated Tests
E. Perez, M.K. Mahadevaiah, C. Zambelli, P. Olivo, Ch. Wenger
Proc. 20th Workshop on Dielectrics in Microelectronics (WODIM 2018), 39 (2018)
(NeuroMem)
In this work the feasibility of accelerated tests at high temperatures to test data retention on RRAM devices was evaluated on HfO2-based 4kbit arrays. By baking the samples at three different temperatures (190, 210, and 230 oC) for 10 h, the activation energy of the degradation process was calculated (1.35 eV). In addition, the retention time was extrapolated to room temperature featuring an acceleration factor of about one billion.

(42) Temperature Impact and Programming Algorithm for RRAM Based Memories
E. Perez, A. Grossi, C. Zambelli, M.K. Mahadevaiah, P. Olivo, Ch. Wenger
Proc. IEEE MTT-S International Microwave Workshop Series on Advanced Materials Processes (IMWS-AMP 2018), (2018)
(NeuroMem)

(43) Data Retention Investigation in Al:HfO2-based RRAM Arrays by using High-Temperature Accelerated Tests
E. Perez, M.K. Mahadevaiah, C. Zambelli, P. Olivo, Ch. Wenger
Journal of Vacuum Science and Technology B 37(1), 012202 (2019)
(NeuroMem)
In this work the feasibility of using accelerated tests at high temperatures to assess the data retention on RRAM devices was evaluated on Al:HfO2-based 1T1R 4kbit arrays. By annealing the samples at three different temperatures (190, 210, and 230 oC) for 10 h, different distributions of retention failure times were obtained and modelled by using Weibull distributions. Based on the temperature dependency of these distributions, the Arrhenius activation energy of the degradation process was calculated (1.35 eV). In addition, the maximum temperature that guarantee a retention time to failure of 10 years lifetime was extrapolated (120 oC).

(44) Epitaxy and Design of GeSn/SiGeSn Heterostructure LEDs
D. Rainko, N. von den Driesch, D. Stange, G. Mussler, U. Breuer, J.M. Hartmann, P. Zaumseil, G. Capellini, Z. Ikonic, S. Mantl, D. Grützmacher, D. Buca
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 19 (2018)
(DFG GeSn Laser)

(45) Effect of C-Doping on Lattice Homogeneity in Expitaxial GaN Layers Revealed by Scanning X-Ray Nano-Diffraction
C. Richter, M.H. Zoellner, S.B. Thapa, P. Storck, T. Schroeder, T.U. Schülli
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 285 (2018)

(46) Theoretical Interpretation of Tilting-Angle Maps in Heteroepitaxial Films
F. Rovaris, M.H. Zöllner, P. Zaumseil, G. Capellini, T. Schröder, P. Storck, M. Haeberlen, G. Schwalb, A. Marzegalli, F. Montalenti
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 113 (2018)
(Siltronic Project)

(47) Misfit-Dislocation Distributions in Heteroepitaxy: From Mesoscale Measurements to Individual Defects and Back
F. Rovaris, M.H. Zoellner, P. Zaumseil, M.A. Schubert, A. Marzegalli, L. Di Gaspare, M. De Seta, T. Schroeder, P. Storck, G. Schwalb, C. Richter, T.U. Schülli, G. Capellini, F. Montalenti
Physical Review Applied 10(5), 05406 (2018)
(Siltronic Project)
We provide an in-depth characterization of the dislocation distribution in partially relaxed Si0.92Ge0.08/Si(001) films. This is achieved by an innovative and general method, combining two stateof-the-art characterization techniques through suitable modeling. After having inferred the dislocation positions from transmission-electron-microscopy images, we theoretically reproduce scanning-x-raydiffraction-microscopy tilt maps measured on the very same region of the sample. We obtain a nearly perfect match between model predictions and experimental data. As a result, we claim that it is possible to establish a local, direct correlation between the dislocatio

(48) Morphological Evolution of Ge/Si Nano-Strips Driven by Rayleigh-Like Instability
M. Salvalaglio, P. Zaumseil, Y. Yamamoto, O. Skibitzki, R. Bergamaschini, T. Schroeder, A. Voigt, G. Capellini
Applied Physics Letters 112(2), 022101 (2018)
(DFG-DACh)
We present the morphological evolution obtained during the annealing of Ge strips grown on Si ridges as a prototypical process for 3D device architectures and nanophotonic applications. In particular, the morphological transition occurring from Ge/Si nanostrips to nanoislands is illustrated. The combined effect of performing annealing at different temperatures and varying the lateral size of the Si ridge underlying the Ge strips is addressed by means of a synergistic experimental and theoretical analysis. Indeed, three dimensional phase-field simulations of surface diffusion, including the contributions of both surface and elastic energy, are exploited to understand the outcomes of annealing experiments. The breakup of Ge/Si strips, due to the activation of surface diffusion at high temperature, is found to be mainly driven by surface-energy reduction, thus pointing to a Rayleigh-like instability. The residual strain is found to play a minor role, only inducing
local effects at the borders of the islands and an enhancement of the instability

(49) Undoped Ge/SiGe Heterostructures: A Platform for Planar Ge Quantum Dots
A. Sammak, D. Sabbagh, N. Hendrick, D. Franke, L.A. Yeoh, M. Virgilio, P. Zaumseil, M.A. Schubert, G. Capellini, M. Veldhorst, G. Scappucci
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 179 (2018)

(50) Suppresion of Sn Segregation During High Temperature Growth of GeSn Nanostructures by Encapsulation
V. Schlykow, G. Capellini, P. Zaumseil, M.A. Schubert, O. Skibitzki, Y. Yamamoto, M. De Seta, L. Di Gaspare, W.M. Klesse, T. Schroeder
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 121 (2018)

(51) Photoluminescence from GeSn Nano-Heterostructures
V. Schlykow, P. Zaumseil, M.A. Schubert, O. Skibitzki, Y. Yamamoto, W.M. Klesse, Y. Hou, M. Virgilio, M. De Seta, L. Di Gaspare, T. Schroeder, G. Capellini
Nanotechnology 29(41), 415702 (2018)
(DFG-DACh)
We investigate the distribution of Sn in GeSn nano-heteroepitaxial clusters deposited at temperatures well exceeding the eutectic temperature of the GeSn system. The 600 °C molecular beam epitaxy on Si-patterned substrates results in the selective growth of GeSn nano-clusters having a 1.4±0.5 at% Sn content. These nano-clusters feature Sn droplets on their faceted surfaces. The subsequent deposition of a thin Ge cap layer induced the incorporation of the Sn atoms segregated on the surface in a thin layer wetting the nano dots surface with 8±0.5 at% Sn. The presence of this wetting layer is associated with a relatively strong photoluminescence emission that we attribute to the direct recombination occurring in the GeSn nano-dots outer region.

(52) Strain Distribution Analysis of Self-Ordered SiGe Nanodot Structures by Nano Beam Diffraction
M.A. Schubert, Y. Yamamoto, Y. Itoh, P. Zaumseil, G. Capellini, K. Washio, B. Tillack
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 245 (2018)

(53) Ultra-Thin Sn-Rich GeSn Quantum Well Structures
J. Schulze, C.J. Clausen, D. Schwarz, P. Zaumseil, G. Capellini, I.A. Fischer
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 233 (2018)
(DFG GeSn Laser)

(54) Temperature Stability of MBE-Grown SixGe1-x-ySny-Structures with High Sn Content
D. Schwarz, I. Fischer, M. Oehme, P. Zaumseil, G. Capellini, J. Schulze
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 211 (2018)
(DFG GeSn Laser)

(55) GeSn/SiGeSn Heterostructure and Multi Quantum Well Lasers
D. Stange, N. von den Driesch, T. Zabel, F. Armand-Pilon, D. Rainko, B. Marzban, P. Zaumseil, J.-M. Hartmann, Z. Ikonic, G. Capellini, S. Mantl, H. Sigg, J. Witzens, D. Grützmacher, D. Buca
ACS Photonics 5(11), 4628 (2018)
(DFG GeSn Laser)
GeSn and SiGeSn are promising materials for the fabrication of a group IV laser source offering a number of design options from bulk to heterostructures and quantum wells. Here, we investigate GeSn/SiGeSn multi quantum wells using the optically pumped laser effect. Three complex heterostructures were grown on top of 200 nm thick strainrelaxed
Ge0.9Sn0.1 buffers. The lasing is investigated in terms of threshold and maximal lasing operation temperature by comparing multiple quantum well to double heterostructure
samples. Pumping under two different wavelengths of 1064 and 1550 nm yields comparable lasing thresholds. The design with multi quantum wells reduces the lasing threshold to 40 ± 5 kW/cm2 at 20 K, almost 10 times lower than for bulk structures. Moreover, 20 K higher maximal lasing temperatures were found for lower energy pumping of 1550 nm.

(56) Advanced GeSn/SiGeSn Group IV Heterostructure Lasers
N. von den Driesch, D. Stange, D. Rainko, I. Povstugar, P. Zaumseil, G. Capellini, T. Schroeder, T. Denneulin, Z. Ikonic, J.-M. Hartmann, H. Sigg, S. Mantl, D. Grützmacher, D. Buca
Advanced Science 5(6), 1700955 (2018)
(DFG GeSn Laser)
Growth and characterization of advanced group IV semiconductor materials with CMOS-compatible applications are demonstrated, both in photonics. The investigated GeSn/SiGeSn heterostructures combine direct bandgap GeSn active layers with indirect gap ternary SiGeSn claddings, a design proven its worth already decades ago in the III–V material system. Different types of double heterostructures and multi-quantum wells (MQWs) are epitaxially grown with varying well thicknesses and barriers. The retaining high material quality of those complex structures is probed by advanced characterization methods, such as atom probe tomography and dark-field electron holography to extract composition parameters and strain, used further for band structure calculations. Special emphasis is put on the impact of carrier confinement and quantization effects, evaluated by photoluminescence and validated by theoretical calculations.As shown, particularly MQW heterostructures promise the highest potential for efficient next generation complementary metal-oxide-semiconductor (CMOS)-compatible group IV lasers.

(57) Technologies for Rad-Hard Resistive Memories
Ch. Wenger
Rad-Hard Semiconductor Memories, 1st Edition, Editors: C. Calligaro, U. Gatti, Chapter 8. Technologies for Rad-Hard Resistive Memories, Rivers Publ., 309 (2018)

(58) Impact of Nickel Silicide on SiGe BiCMOS Devices
D. Wolansky, T. Grabolla, T. Lenke, S. Schulze, P. Zaumseil
Semiconductor Science and Technology 33(12), 124003 (2018)
(Taranto)
Nickel silicide (NiSi) can improve the RF performance of SiGe hetero bipolar transistors (HBT) compared to cobalt silicide (Heinemann et al 2016 IEDM Tech. Dig. 51–4). In this paper, the impact of different procedures to form NiSi on HBT and MOS devices of a 0.13 μm BiCMOS cobalt silicide technology is studied. The different NiSi formations are carried out by partly or fully Ni consumption (PC, FC) for low temperature furnace and low pressure anneals. Our investigations indicate, PC results in rough silicide surfaces and substrate interfaces, whereas FC leads to smooth surfaces and interfaces associated with lower resistivities. FC nickel silicidation at 300 °C and 450 °C exhibits an excessive NiSi growth on the STI edges of n doped source drain (N+SD) regions, reducing the breakdown voltage to substrate or p well. An enhanced NiSi growth is found for all investigated silicide schemes on narrow P+SD regions along polysilicon gates. The leakage current of these structures is caused by enlarged lateral silicidation towards the gates. The enhanced lateral NiSi growth could be suppressed by partly Ni silicidation with furnace anneals at 200 °C or 230 °C.

(59) Self-Ordered Ge Nanodot Fabrication by Reduced Pressure Chemical Vapor Deposition
Y. Yamamoto, Y. Itoh, P. Zaumseil, M.A. Schubert, G. Capellini, K. Washio, B.Tillack
Proc. Americas International Meeting on Electrochemistry and Solid State Science (AiMES 2018), (2018)

(60) Alignment Control of Self-Ordered Three Dimensional SiGe Nanodots
Y. Yamamoto, Y. Itoh, P. Zaumseil, M.A. Schubert, G. Capellini, F. Montalenti, K. Washio, B. Tillack
Semiconductor Science and Technology 33(11), 114014 (2018)
Alignment control of three dimensional (3D) SiGe nanodot arrangements is investigated using a reduced pressure chemical vapor deposition system. Several cycles of SiGe layers with 30% Ge content and Si spacers are deposited by SiH4-GeH4 at 550 °C and SiH4 or SiH2Cl2 at 700 °C, respectively, to form a 3D SiGe nanodot structure. By using SiH4 as a precursor for the Si spacer deposition, SiGe nanodots are aligned at staggered positions resulting in a body-centered tetragonal (BCT) structure, because a checkerboard mesa structured Si surface is formed and the next SiGe nanodot formation occurs at the concave region to reduce surface energy. On the other hand, after planarizing the Si surface with checkerboard structure by chemical mechanical polishing (CMP), the new SiGe nanodot formation occurs directly above the embedded SiGe nanodot located nearest to the Si surface (dot-on-dot). The driving force seems to be local tensile strain formed at the Si surface above the embedded SiGe nanodot. By using SiH2Cl2 as precursor for the Si spacer deposition, a smooth Si surface can be realized on BCT SiGe nanodot structures without CMP process resulting in a vertically aligned SiGe nanodot formation. The local tensile strain formation in Si above SiGe nanodots is confirmed by nano beam diffraction analysis.

(61) Alignment Control of Vertical / Body-Centered-Tetragonal SiGe Nanodot
Y. Yamamoto, Y. Itoh, P. Zaumseil, M.A. Schubert, G. Capellini, K. Washio, B. Tillack
Proc. 12th International WorkShop on New Group IV Semiconductor Nanoelectronics (2018), abstr. (2018)

(62) Influence of Annealing Conditions on Threading Dislocation Density in Ge Deposited on Si by Reduced Pressure Chemical Vapor Deposition
Y. Yamamoto, P. Zaumseil, M.A. Schubert, B. Tillack
Semiconductor Science and Technology 33(12), 124007 (2018)
The influence of annealing conditions on the crystallinity of Ge deposited on Si(001) is
investigated. Ge deposited with postannealing at 800 °C and 850 °C, five cycles of postannealing at 750 °C and 850 °C (temperature-swing postannealing) and several cycles of annealing at 800 °C or 850 °C during the Ge growth by interrupting the deposition step (cyclic annealing) are compared. To check the threading dislocation density (TDD) of the deeper part of the Ge, thinning by HCl vapor phase etching (VPE) followed by Secco defect etching is performed for 5 μm thick Ge of all three annealing variants. By comparing the TDD of the same Ge thickness with and without HCl VPE, TDD reduction by VPE is observed for the sample using the cyclic annealing process only. Lower TDD is observed at higher postannealing temperature. By the five cycles of temperature swinging, TDD becomes around a half compared to conventional postannealing at 850 °C. In the case of the cyclic annealing process significant improvement of TDD is observed with increasing Ge thickness. Even at a maximum temperature of 800 °C, the same or lower TDD levels were observed for higher than 2 μm thick Ge compared to that with five cycles of temperature-swing postannealing. For the sample with cyclic annealing at 800 °C, a lower Si diffusion length into Ge is also observed for the cyclic annealing process indicating a lower thermal budget. A lower amount of tilted Ge planes at the interface is confirmed showing higher crystal quality also in the deeper part of the Ge layer.

(63) Alignment Control of Self-Ordered Three Dimensional SiGe Nanodots
Y. Yamamoto, Y. Itoh, P. Zaumseil, M.A. Schubert, G. Capellini, K. Washio, B. Tillack
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 25 (2018)

(64) Self-Ordered Ge Nanodot Fabrication by Reduced Pressure Chemical Vapor Deposition
Y. Yamamoto, Y. Itoh, P. Zaumseil, M.A. Schubert, G. Capellini, K. Washio, B. Tillack
ECS Transactions 86(7), 259 (2018)
Ge nanodot formation on Si surface and its three dimensional alignment is investigated using a reduced pressure chemical vapor deposition (RPCVD) system. By exposing GeH4 on Si (001) surface at 550oC, a smooth wetting Ge layer is deposited for the first ~0.9 nm, and then Ge nanodot formation occurs as Stranski-Krastanov growth mechanism. The Ge nanodots are randomly distributed with density of ~6×1010 cm-2. By postannealing at
600oC, the Ge nanodots are coalesced. The size and density become ~60 nm diameter 5 nm height and ~1.5×1010 cm-2, respectively. By exposing GeH4 followed by postannealing at 600oC on checkerboard mesa structured Si surface which is fabricated by embedded body-centered tetragonal (BCT) Si0.6Ge0.4 nanodot, the Ge nanodot formation occurs at concave regions of the checkerboard mesa. By repeating Ge nanodot deposition and Si
spacer deposition by two step epitaxy using SiH4 at 600oC and using SiH2Cl2 at 700oC, vertical alignment of the Ge nanodots is observed. The lateral periodicity of the Ge nanodots is the same as that of the BCT Si0.6Ge0.4 nanodot template. The driving force of
the self-ordered alignment is tensile strain of Si spacer surface above the Ge nanodots.

(65) Design and Fabrication of a BiCMOS Dielectric Sensor for Viscosity Measurements: A Possible Solution for Early Detection of COPD
P.S. Zarrin, F.I. Jamal, S. Guha, J. Wessel, D. Kissinger, Ch. Wenger
Biosensors (MDPI) 8(3), 78 (2018)
(EXASENS)
The viscosity variation of sputum is a common symptom of the progression of Chronic Obstructive Pulmonary Disease (COPD). Since the hydration of the sputum defines its viscosity level, dielectric sensors could be used for the characterization of sputum samples collected from patients for early diagnosis of COPD. In this work, a CMOS-based dielectric sensor for the real-time monitoring of sputum viscosity was designed and fabricated. A proper packaging for the ESD-protection and short-circuit prevention of the sensor was developed. The performance evaluation results show that the radio frequency sensor is capable of measuring dielectric constant of biofluids with an accuracy of 4.17%. Integration of this sensor into a portable system will result in a hand-held device capable of measuring viscosity of sputum samples of COPD-patients for diagnostic purposes.

(66) The Thermal Stability of Epitaxial GeSn Layers
P. Zaumseil, Y. Hou, M.A. Schubert, N. von den Driesch, D. Stange, D. Rainko, M. Virgilio, D. Buca, G. Capellini
APL Materials 6(7), 076108 (2018)
(DFG GeSn Laser)

(67) High-Temperature High-Resolution XRD to Analyze the Modification of Heteroepitaxial GeSn/Ge/Si(001) Structures
P. Zaumseil, Y. Hou, N. von den Driesch, D. Stange, D. Rainko, D. Buca, G. Capellini
Proc. 14th Biennial Conference on High-Resolution X-Ray Diffraction and Imaging (XTOP 2018), abstr. (2018)
(Ge Laser)

(68) In-Situ X-Ray Characterization of the Thermal Stability of Epitaxial GeSn/Ge/Si Heterostructures
P. Zaumseil, N. von den Driesch, D. Stange, D. Rainko, D. Buca, G. Capellini
Proc. 1st Joint Conference International SiGe Technology and Device Meeting and International Conference on Silicon Epitaxy and Heterostructures (ISTDM/ICSI 2018), 15 (2018)
(Ge Laser)

(69) Concepts for Closely Mimicking Biological Learning with Memristive Devices: Principles to Emulate Cellular Forms of Learning
M. Ziegler, Ch. Wenger, E. Chicca, H. Kohlstedt
Journal of Applied Physics 124(15), 152003 (2018)
(NeuroMem)
The basic building blocks of every neural network are neurons and their inter-cellular connections, called synapses. In nature, synapses play a crucial role in learning and memory, since they are plastic, which means that they change their state depending on the neural activity of the respectively coupled neurons. In neuromorphic systems, the functionality of neurons and synapses is emulated in hardware systems by employing very large-scale integration technology. In this context, it seems rather natural to use non-volatile memory technology to mimic synaptic functionality. In particular, memristive devices are promising candidates for neuromorphic computing, since they allow one to emulate synaptic functionalities in a detailed way with a significantly reduced power usage and a high packing density. This tutorial aims to provide insight on current investigations in the field to address the following fundamental questions: How can functionalities of synapses be emulated with memristive devices? What are the basic requirements to realize artificial inorganic neurons and synapses? Which material systems and device structures can be used for this purpose? And how can cellular synaptic functionality be used in networks for neuromorphic computing? Even if those questions are part of current research and not yet answered in detail, our aim is to present concepts that address those questions. Furthermore, this tutorial focuses on spiking neural models, which enables mimicking biological computing as realistically as possible.

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