Fraunhofer Institute for Electronic Nano Systems

Chemnitz, Germany

Fraunhofer Institute for Electronic Nano Systems

Chemnitz, Germany
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Kang H.,TU Chemnitz | Sowade E.,TU Chemnitz | Baumann R.R.,TU Chemnitz | Baumann R.R.,Fraunhofer Institute for Electronic Nano Systems
ACS Applied Materials and Interfaces | Year: 2014

We demonstrate intense pulsed light (IPL) sintering of inkjet-printed CuO layers on a primer-coated porous PET substrate to convert the electrically insulating CuO into conductive Cu. With this approach, conductive layers are obtained in less than 1 s after the printing process. The IPL sintering was performed for high productivity with minimum duration and repetition of IPL irradiation to evaluate the effect of pulse number and energy output on the conductivity and morphology of the sintered Cu layers. Depending on the energy output, sheet resistances were measured as 0.355, 0.131, and 0.121 Ω·□-1 by exposure energy of 5.48 (single pulse), 7.03 (double pulse), and 7.48 J·cm-2 (triple pulse), respectively. In contrast, an excessive energy with relatively short pulse duration causes a delamination of the Cu layer. The lowest resistivity of about 55.4 nΩ·m (corresponds to about 30% conductivity of bulk Cu) was obtained by an IPL sintering process of 0.26 s after the printing, which was composed of 2 ms triple pulses with 10 Hz frequency. © 2014 American Chemical Society.

Zichner R.,Fraunhofer Institute for Electronic Nano Systems | Baumann R.R.,Fraunhofer Institute for Electronic Nano Systems | Baumann R.R.,TU Chemnitz
Japanese Journal of Applied Physics | Year: 2013

Vehicle tracking systems based on ultra high frequency (UHF) radio frequency identification (RFID) technology are already introduced to control the access to car parks and corporate premises. For this field of application so-called Windshield RFID transponder labels are used, which are applied to the inside of the windshield. State of the art for manufacturing these transponder antennas is the traditional lithography/etching approach. Furthermore the performance of these transponders is limited to a reading distance of approximately 5m which results in car speed limit of 5 km/h for identification. However, to achieve improved performance compared to existing all-purpose transponders and a dramatic cost reduction, an optimized antenna design is needed which takes into account the special dielectric and in particular metallic car environment of the tag and an roll-to-roll (R2R) printing manufacturing process. In this paper we focus on the development of a customized UHF RFID transponder antenna design, which is adopted for vehicle geometry as well as R2R screen printing manufacturing processes. © 2013 The Japan Society of Applied Physics.

Zienert A.,TU Chemnitz | Schuster J.,Fraunhofer Institute for Electronic Nano Systems | Gessner T.,TU Chemnitz | Gessner T.,Fraunhofer Institute for Electronic Nano Systems
Nanotechnology | Year: 2014

We study quasi-ballistic electron transport in metallic (6, 0) carbon nanotubes (CNTs) of variable length in contact with Al, Cu, Pd, Pt, Ag, and Au electrodes by using the nonequilibrium Green's function formalism in combination with either density functional theory or self-consistent extended Hückel theory. We find good agreement between both. Visualizing the local device density of states of the systems gives a descriptive link between electronic structure and transport properties. In comparison with bare finite and infinite tubes, we show that the electronic structure of short metallic CNTs is strongly modified by the presence of the metallic electrodes, which leads to pronounced size effects in the conductance. The mean conductances and linear response currents allow a ranking of the metals regarding their ability to form low- Ohmic contacts with the nanotube: Ag ≲ Au < Cu 蠐 Pt ≈ Pd 蠐 Al. These findings are contrasted with similar trends in contact distance, binding energy, calculated work function of the metal surfaces, and various results from literature. © 2014 IOP Publishing Ltd.

Krasselt C.,TU Chemnitz | Schuster J.,TU Chemnitz | Schuster J.,Fraunhofer Institute for Electronic Nano Systems | Von Borczyskowski C.,TU Chemnitz
Physical Chemistry Chemical Physics | Year: 2011

Blinking dynamics of CdSe/ZnS semiconductor quantum dots (QD) are characterized by (truncated) power law distributions exhibiting a wide dynamic range in probability densities and time scales both for off- and on-times. QDs were immobilized on silicon oxide surfaces with varying grades of hydroxylation and silanol group densities, respectively. While the off-time distributions remain unaffected by changing the surface properties of the silicon oxide, a deviation from the power law dependence is observed in the case of on-times. This deviation can be described by a superimposed single exponential function and depends critically on the local silanol group density. Furthermore, QDs in close proximity to silanol groups exhibit both high average photoluminescence intensities and large on-time fractions. The effect is attributed to an interaction between the QDs and the silanol groups which creates new or deepens already existing hole trap states within the ZnS shell. This interpretation is consistent with the trapping model introduced by Verberk et al. (R. Verberk, A. M. van Oijen and M. Orrit, Phys. Rev. B, 2002, 66, 233202). © 2011 the Owner Societies.

Hammerschmidt J.,TU Chemnitz | Wolf F.M.,TU Chemnitz | Goedel W.A.,TU Chemnitz | Baumann R.R.,TU Chemnitz | Baumann R.R.,Fraunhofer Institute for Electronic Nano Systems
Langmuir | Year: 2012

Inkjet printing is employed to apply a mechanically stable reinforcing pattern to polymeric microsieves prepared by float casting, where particles are used as molds for the pores. A mixture of silica particles and nonvolatile monomers is cast onto a water surface and subsequently photopolymerized to produce membranes consisting of a polymer film with embedded particles. These composite membranes are transferred onto an aluminum foil. Subsequently, a UV-curable ink is directly inkjet-printed onto the membranes in line patterns of grids or honeycombs and cured by UV radiation to create a mechanically reinforcing pattern. Afterwards, the particles and the aluminum foil are removed by chemical etching. The reinforcing pattern overcasts 40% of the previously manufactured membrane, is mechanically stable, and gives the microsieves such a robustness that they can be handled in further manufacturing processes. © 2012 American Chemical Society.

Braeuer J.,Fraunhofer Institute for Electronic Nano Systems | Gessner T.,Fraunhofer Institute for Electronic Nano Systems
Journal of Micromechanics and Microengineering | Year: 2014

This paper focuses on direct deposition and patterning of reactive and nano-scale multilayer films at wafer level. These multilayer structures are called integrated reactive material systems (iRMS). In contrast to the typically used nickel (Ni)/ aluminum (Al) systems, in this work we needed to have our total multilayer film thicknesses smaller than 2.5 μm to reduce stress within the multilayer as well as deposition costs. Thus, we introduced new high energetic iRMS. These films were deposited by using alternating magnetron sputtering from high purity Al- and palladium (Pd)-targets to obtain films with a defined Al:Pd atomic ratio. In this paper, we present the result for reaction characteristics and reaction velocities which were up to 72.5 m s-1 for bond frames with lateral dimensions as low as 20 μm. Furthermore, the feasibility of silicon (Si)-Si, Si-glass as well as Si-ceramic hermetic and metallic wafer bonding at room temperature is presented. We show that by using this bond technology, strong (maximum shear strengths of 235 MPa) and hermetically sealed bond interfaces can be achieved without any additional solder material. © 2014 IOP Publishing Ltd.

Zienert A.,TU Chemnitz | Schuster J.,Fraunhofer Institute for Electronic Nano Systems | Gessner T.,Fraunhofer Institute for Electronic Nano Systems
Microelectronic Engineering | Year: 2013

In the present work we study the electronic transport properties of finite length single-wall carbon nanotubes (CNTs) by comparing three different theoretical frameworks. A simple model is used to describe the electrodes and the way they are attached to both ends of the CNT. Electron transport calculations are carried out on three different levels of sophistication. That are the Landauer transport formalism in combination with single-orbital tight-binding, extended Hückel theory or density functional theory. The quantum mechanical transmission which plays a central role in Landauer theory is calculated by means of equilibrium and non-equilibrium Green's function methods. Results of the three approaches are compared and discussed. © 2013 Elsevier B.V. All rights reserved.

Zichner R.,Fraunhofer Institute for Electronic Nano Systems | Baumann R.R.,Fraunhofer Institute for Electronic Nano Systems | Baumann R.R.,TU Chemnitz
Advances in Radio Science | Year: 2013

Miniaturized, highly integrated wireless communication systems are used in many fields like logistics and mobile communications. Often multiple antenna structures are integrated in a single product. To achieve such a high level of integration the antenna structures are manufactured e.g. from flexible boards or via LDS (laser direct structuring) which allows the production of complex monopole or dipole antennas with three-dimensionally curved shapes. Main drawbacks are the sophisticated production process steps and their costs. The additive deposition of metallic inks or pastes by a printing process is an alternative manufacturing method with reduced cost. To implement such printed antennas we investigated in the fields of antenna design, simulation, printing technology and characterization. The chosen example of use was a customized dipole antenna for a Radio Frequency Identification application. The results prove the intended functionality of the printed dipole in regard to a highly cost efficient printing manufacturing. © 2011 Author(s).

Georgi C.,TU Chemnitz | Hildebrandt A.,TU Chemnitz | Waechtler T.,Fraunhofer Institute for Electronic Nano Systems | Schulz S.E.,Fraunhofer Institute for Electronic Nano Systems | And 2 more authors.
Journal of Materials Chemistry C | Year: 2014

Low melting or liquid cobalt(0) MOCVD precursors of type [Co 2(CO)6(η2-RCCR')] (R = H, R' = (CH 3)3Si, nC4H9, nC5H11, nC6H 13, nC7H15; R = nC 3H7, R' = (CH3)3Si, CH3; R = R' = C2H5, (CH3)3Si) have been prepared by the reaction of the appropriate alkynes with Co2(CO) 8. Variation of the substituents at the C,C triple bond allowed the study of their influence on the thermal behaviour and vapour pressure. These measurements showed that the cobalt(0) precursors are suitable for application within the MOCVD (Metal-Organic Chemical Vapour Deposition) process. Decomposing deposition of the cobalt precursors was realized in a home-built vertical cold-wall CVD reactor under mild conditions without any addition of co-reactants. The obtained dense and conformal cobalt layers have been characterized by SEM, EDX and XPS measurements. Depending on the precursor applied, pure cobalt films (96.7% Co) or mixtures of cobalt, carbon and cobalt oxide with varying composition with layer thicknesses of 35-90 nm were formed. © 2014 the Partner Organisations.

Braeuer J.,Fraunhofer Institute for Electronic Nano Systems | Besser J.,Fraunhofer Institute for Electronic Nano Systems | Wiemer M.,Fraunhofer Institute for Electronic Nano Systems | Gessner T.,Fraunhofer Institute for Electronic Nano Systems | Gessner T.,TU Chemnitz
Sensors and Actuators, A: Physical | Year: 2012

Considering the demand for low temperature bonding processes in 3D integration and packaging of microelectronic or micromechanical components, this paper introduces a method that uses a specific form of local heat generation, which is based on nano scale reactive material systems. Such systems consist of several layers of minimum two different materials with nano scale thicknesses. These layers generate a self-propagating and exothermic reaction during their intermixing. The resulting heat can be used as the heat source for bonding processes such as solder bonding of micro components. In contrast to other researchers, who focus on relatively thick Ni/Al foils for joining macroscopic parts, we focus on the direct deposition of reactive multilayer systems. The principle of this method is demonstrated by reactive bonding, for which we use different energetic systems. The main part of this paper deals with the preparation and investigation of integrated reactive material systems. © 2012 Elsevier B.V. All rights reserved.

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