Conference contributions

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Jatal, Wael; Tonisch, Katja; Baumann, Uwe; Schwierz, Frank; Pezoldt, Jörg
GaN HEMTs on Si substrate with high cutoff frequency. - In: 2014 10th International Conference on Advanced Semiconductor Devices & Microsystems (ASDAM), ISBN 978-1-4799-5476-6, (2014), insges. 4 S.

We report on GaN HEMTs on Si substrates with high cutoff frequency and low contact resistance. HEMTs with two barriers designs and two source/drain metallization schemes have been fabricated and characterized. Our 100-nm gate transistors show a maximum drain current density of 1.4 A/mm and a peak transconductance of 427 mS/mm. The fastet transistors have a gate length of 80 nm and achieve a cutoff frequency fT of 180 GHz. This is the best fT performance reported for GaN HEMTs on Si reported so far and rivals the fastest GaN HEMTs on SiC with comparable gate length.



http://dx.doi.org/10.1109/ASDAM.2014.6998660
Sippel, Philipp; Schwarzburg, Klaus; Borgwardt, Mario; Elagin, Mikaela; Heitz, Simon; Semtsiv, Mykhaylo P.; Masselink, W. Ted; Hannappel, Thomas; Eichberger, Rainer
Dynamics and two photon intersubband absorption of photovoltaic quantum structures. - In: IEEE 40th Photovoltaic Specialists Conference (PVSC), 2014, (2014), S. 3254-3257

http://dx.doi.org/10.1109/PVSC.2014.6925630
Hanitsch, Stefan; Grohmann, Steffi; Berg, Albrecht; Moje, J.; Hoffmann, Martin
Method for testing of hydrogel sensor coatings. - In: Biomedical engineering, ISSN 1862-278X, Bd. 59.2014, Suppl. 1, S. S31-S33

http://dx.doi.org/10.1515/bmt-2014-5000
Stubenrauch, Mike; Hanitsch, Stefan; Fischer, Robert; Bartsch, Heike; Straube, Anja; Hoffmann, Martin; Witte, Hartmut
BioMEMS for analysis and synthesis in life sciences. - In: Biomedical engineering, ISSN 1862-278X, Bd. 59.2014, Suppl. 1, S. S127

http://dx.doi.org/10.1515/bmt-2014-5001
Hartmann, Robert; Koch, Michael
CFRP and aluminum foam hybrid composites. - In: Shaping the future by engineering, (2014), insges. 9 S.

One way to minimize the energy consumption of production processes is to reduce moving masses in machinery. This reduction of mass can be carried out through the exchange of solid material, like steel or aluminum, with hybrid materials. These hybrid materials combine application-oriented different type of materials and their properties. This paper deals with the RTM manufacturing process and FEM simulation of such a hybrid material. By using the sandwich design method two tensile-stiff carbon fiber reinforced plastic (CFRP) layers are connected to a low-density aluminum foam (AF) core in order to produce hereafter parts with high weight-specific bending stiffness. At the beginning of this paper an analytical calculation method on the basis of the beam theory is developed, which allows an estimation of the achievable mechanical properties of the composite. The bending stiffness of such a composite is mainly determined by the outer layer modulus and the gravity axis distance of the outer layers. These findings are incorporated into the development of a FEM model, which allows the simulation of various load cases with selectable composite structure. The challenge in developing this model is the implementation of the material-specific peculiarities. These include the anisotropy of the CFRP layers and the core structure of the AF. An experimental plan is developed by using the DoE method. It allows the determination of the RTM process parameters, which will lead to components with the highest weight-specific bending stiffness. On this account preliminary tests are carried out to identify the usable range of injection pressure, mold temperature and compression pressure of the press. This paper can demonstrate, that the production of CFRP/ AF hybrid material by means of the RTM process is feasible. The first manufactured specimens exhibit no displacement of the fibers and almost no air inclusions. The simulation of CFRP/ AF hybrid material could be implemented. The anisotropy of the CFRP layers can be simulated with the ANSYS fiber fracture software ACP. The structure of the AS core can be mapped with great computational effort. The next step is the execution of the developed experimental plan with an especially designed RTM mold for sandwich composites.



http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-100:6
Fiebig, Christian; Koch, Michael
The influence of fiber undulation on the mechanical properties of FRP-laminates. - In: Shaping the future by engineering, (2014), insges. 8 S.

http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-099:3
Woyan, Felix; Koch, Michael; Koch, Michael *1955-2017*; Schneidmadel, Stefan
Process parameters affecting the quality of functionalized in-mold decoration injection molded composites. - In: Shaping the future by engineering, (2014), insges. 9 S.

This report studies the fundamental parameters affecting the wash-off and the warpage of parts manufactured in in-mold decoration process (IMD). The purpose is to derive a process model for describing the wash-off and the warpage of the parts as a function of the main influencing parameters based on a dimensional analysis. In order to investigate the influence of the materials and various processing conditions, a test mold was created for experiments and simulations were carried out. First of all the main influencing factors have been identified. To quantify the influence of each factor, a full factorial design was used. A DOE of process parameters including injection speed, injection pressure, melt temperature, mold temperature, post-injection pressure and the material were designed and executed. Based on the DOE specimens with a 250 [my]m and 375 [my]m thick PC film and a part thickness of 2 mm and 3 mm made from different thermoplastics were produced. In addition, the results of the experiment were compared with the simulation.



http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-095:0
Röder, Martin; Koch, Michael
Integration of connecting elements in hybrid-composite components. - In: Shaping the future by engineering, (2014), insges. 7 S.

http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-089:1
Bruchmüller, Matthias; Koch, Michael;
Improvement of tribological properties of plastic compounds. - In: Shaping the future by engineering, (2014), insges. 7 S.

http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-084:0