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Parallel arrays of Schottky barrier nanowire field effect transistors： Nanoscopic effects for macroscopic current output

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Nano Research 2013年第6期6卷 381-388页

作者： Sebastian Pregl Walter M. Weber Daijiro Nozaki Jens Kunstmann Larysa Baraban Joerg Opitz Thomas Mikolajick Gianaurelio Cuniberti institute for Materials Science and Max Bergmann Center of Biomaterials TU Dresden Dresden 01062 Germany NaMLab GmbH Dresden 01187 Germany fraunhofer institute izfp dresden Dresden 01109 Germany institute for Semiconductors and Microsystems Technology TU Dresden Dresden 01187 Germany Division of IT Convergence Engineering POSTECH Pohang Korea

We present novel Schottky barrier field effect transistors consisting of a parallel array of bottom-up grown silicon nanowires that are able to deliver high current outputs. Axial silicidation of the nanowires is used to create defined Schottky junctions leading to on/off current ratios of up to 106. The device concept leverages the unique transport properties of nanoscale junctions to boost device performance for macroscopic applications. Using parallel arrays, on-currents of over 500 gA at a source-drain voltage of 0.5 V can be achieved. The transconductance is thus increased significantly while maintaining the transfer characteristics of single nanowire devices. By incorporating several hundred nanowires into the parallel arra36 the yield of functioning transistors is dramatically increased and device- to-device variability is reduced compared to single devices. This new nanowire- based platform provides sufficient current output to be employed as a transducer for biosensors or a driving stage for organic light-emitting diodes （LEDs）, while the bottom-up nature of the fabrication procedure means it can provide building blocks for novel printable electronic devices.

关键词： silicon nanowire effective Schottky barrier lowering parallel arra^electric field enhancement output current amplification

Pressureless sintering of ZrC with variable stoichiometry

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Journal of Advanced Ceramics 2017年第2期6卷 165-175页

作者： Katrin SCH(O)NFELD Hans-Peter MARTIN Alexander MICHAELIS fraunhofer institute for Ceramic Technologies and Systems IKTS Dresden Germany

This paper presents the experiments on the synthesis of zirconium carbide (ZrC) using carbothermal reduction of zirconia (ZrO2).The ratio of ZrO2∶C is used to adapt ZrCxOy with x＜ 1 or ZrC + *** modification of ZrCxOy and the total carbon amount allows the use of pressureless sintering method in combination with sintering temperatures ≤ 2000 ℃.Fully densified ZrC products are *** relevant details of ZrC formation are investigated by X-ray diffraction (XRD).The sintered products are characterized by XRD,field emission scanning electron microscopy (FESEM),as well as mechanical and electrical *** and FESEM investigations show that ZrCxOy is formed during the manufacturing *** grain size and additional zirconia or carbon are related to the ZrO2∶C ratio of the starting powder *** strength up to 300 MPa,Young's modulus up to 400 GPa,fracture toughness up to 4.1 MPa·m1/2,and electrical resistance at room temperature around 10-4 Ω.cm are reached by the pressureless sintered ZrC.

关键词： zirconium carbide (ZrC) carbothermal reduction sintering mechanical properties electrical properties

Data Mining and Machine Learning Methods Applied to A Numerical Clinching Model

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Computer Modeling in Engineering & Sciences 2018年第12期117卷 387-423页

作者： Marco Gotz Ferenc Leichsenring Thomas Kropp Peter Müller Tobias Falk Wolfgang Graf Michael Kaliske Welf-Guntram Drossel institute for Structural Analysis Technische UniversitatDresdenGermany fraunhofer institute for Machine Tools and Forming Technology DresdenGermany

Numerical mechanical models used for design of structures and processes are very complex and high-dimensionally *** understanding of the model characteristics is of interest for engineering tasks and subsequently for an efficient *** analysis methods are known and available to gain insight into existing *** this contribution,selected methods from various fields are applied to a real world mechanical engineering example of a currently developed clinching *** selection of introduced methods comprises techniques of machine learning and data mining,in which the utilization is aiming at a decreased numerical *** methods of choice are basically discussed and references are given as well as challenges in the context of meta-modelling and sensitivities are *** incremental knowledge gain is provided by a step-bystep application of the numerical methods,whereas resulting consequences for further applications are ***,a visualisation method aiming at an easy design guideline is *** visual decision maps incorporate the uncertainty coming from the reduction of dimensionality and can be applied in early stage of design.

关键词： Design data mining computational intelligence meta-modelling permissible design space sensitivity analysis self-organizing maps inverse problem early stage of design clinching

Ultrasound enhanced friction stir welding of aluminum and steel： Process and properties of EN AW 6061/DC04-Joints

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Journal of Materials Science & Technology 2018年第1期34卷 163-172页

作者： Marco Thoma Guntram Wagner Benjamin Straβ Bernd Wolter Sigrid Benferc Wolfram Furbeth Chair of Composites and Material Compounds Chemnitz University of Technology Chemnitz 09125 Germany fraunhofer institute for Nondestructive Testing izfp Saarbrucken 66123 Germany DECHEMA-Forschungsinstitut Frankfurt am Main 60486 Germany

In this work, the joining of aluminum to steel was conducted by ultrasound enhanced friction stir weld- ing （USE-FSW）. The power ultrasound was introduced into one of the metal sheets by an ultrasonic roll seam module synchronously to the FSW-process. The effect of the ultrasound on the resulting welds, their microstructure and their corrosion properties was investigated by light and scanning electron microscopy and corrosion investigations. The USE-FSW-joints showed less and smaller steel particles in the nugget zone as well as a thinner continuous intermetallic phase of FeAl3 at the interface. The nondestructive testing method of computed laminography proved the observations made by optic microscopy due to non-porous joints for both techniques. Corrosion investigations showed only low corrosion current densities and no enhanced galvanic corrosion for the EN AW-6061/DC04-hybrid joints in sodium chloride solution.

关键词： Friction stir welding Ultrasound enhancement Dissimilar joints Corrosion

Coulomb-actuated microbeams revisited: experimental and numerical modal decomposition of the saddle-node bifurcation

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Microsystems & Nanoengineering 2021年第3期7卷 111-123页

作者： Anton Melnikov Hermann A.G.Schenk Jorge M.Monsalve Franziska Wall Michael Stolz Andreas Mrosk Sergiu Langa Bert Kaiser fraunhofer institute for Photonic Microsystems IPMS Dresden 01109Germany Arioso Systems GmbH Dresden 01109Germany Brandenburg University of Technology Cottbus-Senftenberg Cottbus 03046Germany

Electrostatic micromechanical actuators have numerous applicati ons in scie nee and *** many applications,they are operated in a narrow frequency range close to resonanee and at a drive voltage of low ***,new applications,such as microelectromechanical systems(MEMS)microspeakers(μSpeakers),have emerged that require operation over a wide frequency and dynamic *** the dynamic performance under such circumstances is still highly ***-of-the-art finite element analysis struggles with pull-in instability and does not deliver the necessary in formation about un stable equilibrium states *** lumped-parameter models amenable to direct physical interpretation are *** inhibits the in dispensable in-depth analysis of the dynamic stability of such *** this paper,we take a major step towards mending the *** combining the finite element method(FEM)with an arc-length solver,we obtain the full bifurcation diagram for electrostatic actuators based on prismatic Euler-Bernoulli beams.A subsequent modal analysis then shows that within very narrow error margins,it is exclusively the lowest Euler-Bernoulli eigenmode that dominates the beam physics over the entire relevant drive voltage *** experiment directly recording the deflection profile of a MEMS microbeam is performed and confirms the numerical findings with astonishing *** enables modeling the system using a single spatial degree of freedom.

关键词： bifurcation modal narrow

Targeting new ways for large-scale,high-speed surface functionalization using direct laser interference patterning in a roll-to-roll process

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International Journal of Extreme Manufacturing 2023年第3期5卷 569-583页

作者： Christoph Zwahr Nicolas Serey Lukas Nitschke Christian Bischoff Ulrich Radel Alexandra Meyer Penghui Zhu Wilhelm Pfleging Laser Precision Manufacturing Fraunhofer Institute for Material and Beam Technology(IWS)DresdenGermany Topag Lasertechnik GmbH DarmstadtGermany institute of Manufacturing Science and Engineering Technical University DresdenDresdenGermany institute for Applied Materials—Applied Materials Physics(IAM-AWP) Karlsruhe Institute of Technology(KIT)Eggenstein-LeopoldshafenGermany

Direct Laser Interference Patterning(DLIP)is used to texture current collector foils in a roll-to-roll process using a high-power picosecond pulsed laser system operating at either fundamental wavelength of 1064 nm or 2nd harmonic of 532 *** raw beam having a diameter of 3 mm@1/e^(2) is shaped into an elongated top-hat intensity profile using a diffractive so-called FBS■-L element and cylindrical *** shaped beam is split into its diffraction orders,where the two first orders are parallelized and guided into a galvanometer *** deflected beams inside the scan head are recombined with an F-theta objective on the working position generating the interference *** DLIP spot has a line-like interference pattern with about 15μm spatial *** fluences of up to 8 J cm^(-2) were achieved using a maximum pulse energy of 0.6 ***,an in-house built roll-to-roll machine was *** this setup,aluminum and copper foil of 20μm and 9μm thickness,respectively,could be *** to current collector structuring coating of composite electrode material took *** case of lithium nickel manganese cobalt oxide(NMC 622)cathode deposited onto textured aluminum current collector,an increased specific discharge capacity could be achieved at a C-rate of 1℃.For the silicon/graphite anode material deposited onto textured copper current collector,an improved rate capability at all C-rates between C/10 and 5℃ was *** rate capability was increased up to 100%compared to reference *** C-rates between C/2 and 2℃,the specific discharge capacity was increased to 200 mAh g^(-1),while the reference electrodes with untextured current collector foils provided a specific discharge capacity of 100 m Ah g^(-1),showing the potential of the DLIP technology for cost-effective production of battery cells with increased cycle lifetime.

关键词： DLIP lithium-ion battery surface texturing copper aluminum

The role of polysulfide-saturation in electrolytes for high power applications of real world Li-S pouch cells

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Nano Research 2023年第6期16卷 8313-8320页

作者： Tom Boenke Sebastian Kirchhoff Florian SReuter Florian Schmidt Christine Weller Susanne Dörfler Kai Schwedtmann Paul Härtel Thomas Abendroth Holger Althues Jan J.Weig Stefan Kaskel Technische Universität dresden Chair of Inorganic Chemistry IBergstr.6601069 DresdenGermany fraunhofer institute for Material and Beam Technology(IWS) Winterbergstr.2801277 DresdenGermany Technische Universität dresden Chair of Inorganic Molecular ChemistryMommsenstraße 401069 DresdenGermany

The lithium-sulfur(Li-S)technology is the most promising candidate for next-generation batteries due to its high theoretical specific energy and steady progress for applications requiring lightweight batteries such as aviation or heavy electric *** these applications,however,the rate capability of Li-S cells requires significant *** electrolyte formulations in Li-S batteries enable new pathways for cell development and adjustment of all ***,their rate capability at pouch cell level is often neither evaluated nor compared to state of the art(SOTA)LiTFSI/dimethoxyethane/dioxolane(LITFSI:lithium-bis(trifluoromethylsulfonyl)imide)***,the combination of the sparingly polysulfide(PS)solvating hexylmethylether/1,2-dimethoxyethane(HME/DME)electrolyte and highly conductive carbon nanotube Buckypaper(CNT-BP)with low porosity was evaluated in both coin and pouch cells and compared to dimethoxyethane/dioxolane reference *** advanced sulfur transfer melt infiltration was employed for cathode production with *** Li+ion coordination in the HME/DME electrolyte was investigated by nuclear magnetic resonance(NMR)and Raman ***,ionic conductivity and viscosity was investigated for the pristine electrolyte and a polysulfide-statured *** electrolytes,DME/DOL-1/1(DOL:1,3-dioxolane)and HME/DME-8/2,are then combined with CNT-BP and transferred to multi-layered pouch *** study reveals that the ionic conductivity of the electrolyte increases drastically over state of(dis)charge especially for DME/DOL electrolyte and lean electrolyte regime leading to a better rate capability for the sparingly polysulfide solvating *** evaluation in prototype cells is an important step towards bespoke adaption of Li-S batteries for practical applications.

关键词： lithium-sulfur pouch cell polysulfide solubility electrolyte characterization high power

Compliant Mechanism Synthesis by Using Elastic Similitude

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Chinese Journal of Mechanical Engineering 2015年第4期28卷 769-775页

作者： HANKE Uwe HAMPEL Peter COMSA Andrei MODLER Niels MODLER Karl-Heinz institute of Solid Mechanics TU Dresden 01069 Dresden Germany institute of Lightweight Engineering and Polymer Technology TU Dresden 01307 Dresden Germany

Compliant mechanisms have several advantages, especially smaller number of elements and therefore less movable joints. The flexural members furthermore allow an integration of special functions like balancing or locking. Especially fiber reinforced materials exhibit a wide range of function integration considering their compliance in passive as well active applications. To take advantage of compliant elements in applications a robust synthesis tool is needed. The synthesis based on topology optimization method or the pseudo rigid body approach leads to complex structures. Considering the use of fiber reinforced material a synthesis approach which leads to less complex structures is more suitable. For building up simple structures, with only one cantilever beam as compliant element（B） a graphical approach using the elastic similitude is the most efficient method. A step-by-step synthesis procedure is presented to synthesize compliant mechanisms with rotatory joints（R） and prismatic joints（P） to develop RRB/PRB- and RPB-linkages. Using the elastic similitude to implement these results into a graphical synthesis algorithm is the innovation part of this paper. It can be shown that this approach leads to a comfortable handling of beam elements during the synthesis, where the two free parameters can be directly coupled to scale and fix the orientation of the beam element. This advantage inherently shortens the development process. In giving an example the focus lies of the experimental approach, which also shows that the simple BERNOULLI beam model is valid and so the synthesis by using the elastic similitude. The method is presented and discussed by using an application for a cup holder mechanism made of fiber reinforced material.

关键词： Compliant mechanism synthesis elastic similitude

Bottom-up synthesis of ultrathin straight platinum nanowires： Electric field impact

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Nano Research 2013年第5期6卷 303-311页

作者： Alexander Nerowski Joerg Opitz Larysa Baraban Gianaurelio Cuniberti institute far Materials Science and Max Bergmann Center of Biomaterials Dresden University of Technology Dresden 01062 Germany fraunhofer institute for Non-Destructive Testing Dresden 01109 Germany Division o fiT Convergence Engineering POSTECH Pohang 790-784 Republic of Korea

We present a study of the electric field effect on electrochemically grown ultrathin, straight platinum nanowires with minimum diameter of 15 nm and length in the micrometer range, synthesized on a silicon oxide substrate between metal electrodes in H2PtC16 solution. The influence of the concentration of the platinum- containing acid and the frequency of the applied voltage on the diameter of the nanowires is discussed with a corresponding theoretical analysis. We demonstrate for the first time that the electric field profile, provided by the specific geometry of the metal electrodes, dramatically influences the growth and morphology of the nanowires. Finally, we provide guidelines for the controlled fabrication and contacting of straight, ultrathin metal wires, eliminating branching and dendritic growth, which is one of the main shortcomings of the current bottom-up nanotechnology. The proposed concept of self-assembly of thin nanowires, influenced by the electric field, potentially represents a new route for guided nanocontacting via smart design of the electrode geometry. The possible applications reach from nanoelectronics to gas sensors and biosensors.

关键词： bottom-up growth directed electrochemicalnanowire assembly(DENA) metal nanowires nanostructuring nanoelectronics local electric field