TY - CHAP A1 - Sievers, Jan A1 - Villringer, Claus A1 - Lebek, Werner A1 - Gilani, Taravat Saeb A1 - Laufer, Jan T1 - Photoacoustic tomography using a Fabry-Perot sensor with homogeneous optical thickness and wide-field camera-based detection T2 - Opto-Acoustic Methods and Applications in Biophotonics VI N2 - Fabry-Perot (FP) sensors are typically read out using a raster scan to acquire tomographic Photoacoustic (PA) images. To speed up the recording time, wide-field illumination of the sensor in combination with a camera as detector can be used. In this study, an sCMOS camera and wavelengths around 517 nm are used to interrogate a FP sensor with a homogeneous optical thickness over a 4 cm2 aperture. The recorded time series show PA signals are acquired over the entire area of the interrogation beam. The performance of the system, such as the noise equivalent pressure, is evaluated. KW - photoacoustic tomograph KW - Fabry-Perot sensor KW - camera-based setup KW - photopolymer KW - polyvinyl cinnamate KW - interferometer transfer function KW - acoustic sensitivity KW - detection aperture Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-17850 ER - TY - CHAP A1 - Lebek, Werner A1 - Heyroth, Frank A1 - Syrowatka, Frank A1 - Villringer, Claus A1 - Goerlitz, Sylvia A1 - Laufer, Jan T1 - Evaluation of fabrication methods for Fabry-Perot polymer film ultrasound sensors T2 - Opto-Acoustic Methods and Applications in Biophotonics VI N2 - Fabry-Pèrot (FP) interferometer sensors enable highly sensitive backward mode acoustic detection in Photoacoustic (PA) imaging. They are transparent to the excitation wavelength, can be placed directly next to the PA source, and offer a broadband frequency response and high acoustic sensitivity. PA tomography using parallelized detection requires high spatial uniformity of the optical and acoustic properties, which can be hampered by contaminations during fabrication that lead to the formation of inhomogeneities and artefacts. The quality and homogeneity of the dielectric and polymer layers have a direct effect on the maximum optical phase sensitivity, and hence acoustic sensitivity. In this study, cross-sectional images of FP sensors were obtained using focused ion beam milling and ultramicrotomy followed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) to evaluate different fabrication methods. KW - photoacoustic imaging KW - Fabry-Perot sensor KW - parylene-C KW - cocus ion beam KW - electron microscopy Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-17864 ER - TY - THES A1 - Lux, Helge T1 - Carbon-based functional Materials for Application in Photonics, Optoelectronics and Sensorics N2 - In this work, two different processes to deposit Graphene-based transparent conductive films on arbitrary insulting substrates have been developed and examined. The first process is a PE-CVD, based on a gas mixture containing hydrocarbons (e.g. methane) inside a vacuum chamber where the insulating substrates are placed on a temperature controlled heating plate. The second process uses a pulsed filtered vacuum arc system (Phi-HCA) to homogeneously deposit a small, well defined amount of carbon on heated substrates. The substrates are tilted with respect to the particle beam and placed on a heating plate. A gas atmosphere consisting of Argon or Argon/Hydrogen decreases the particle energy and influences the morphology of the growing film. For both processes, Scanning Tunneling Microscopy (STM), Transmission Electron Microscopy (TEM) and Raman spectra have been used for a thorough characterization of the samples in order to optimize the growth parameters. Subsequently, the results (sheet resistance, Hall mobility, transmittance) have been compared with respect to the state of the art, reported in literature. The best carbon layers have a surface resistance of 5E3 Ohm_sqr while the optical transparency of the coatings is 88% with an excellent homogeneity over areas of several cm^2. Both for the PE-CVD and the Phi-HCA, the area of deposition is only limited by the respective area of the heated surface. The obtained results and the fact, that the process can be compatible with most semiconductor fabrication processes, makes them promising for various industrial applications. KW - graphene KW - carbon KW - HCA KW - PECVD KW - Raman Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13916 ER - TY - CHAP A1 - Steglich, Patrick A1 - Mai, Andreas T1 - Analysis of BTO-on-Si-waveguides for energy-efficient electro-optical modulators T2 - Proc. SPIE 11775, Integrated Optics: Design, Devices, Systems and Applications VI N2 - In this work, we analyze a horizontal slot waveguide configuration, which evaluates the potential for an integration of barium titanate (BTO) based modulators into a photonic integrated circuit (PIC) technology based on siliconon- insulator (SOI) wafer. The waveguide configuration consists of a doped crystal silicon layer, a Ba0:7Sr0:3TiO3 (BST) template layer, a barium titanate (BTO) layer and a doped poly-silicon layer on top. In contrast to current approaches, we analyze the performance of this waveguide-structure by using a vertical electrode configuration that is formed by the doped silicon layer. In this way, the electric field strength is dramatically increased compared to current horizontal electrode configuration. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13934 ER - TY - CHAP A1 - Villringer, Claus A1 - Gilani, Taravat Saeb A1 - Zhang, Edward A1 - Pulwer, Silvio A1 - Steglich, Patrick A1 - Schrader, Sigurd A1 - Laufer, Jan T1 - Development of tuneable Fabry-Pérot sensors for parallelised photoacoustic signal acquisition T2 - Proc. SPIE 10878, Photons Plus Ultrasound: Imaging and Sensing 2019, 108780M (8 March 2019) N2 - Fabry-Pérot (FP) sensors have enabled high resolution 3D photoacoustic (PA) imaging in backward mode. However, raster-scanning of the interrogation laser beam across the sensor can result in slow 3D image acquisition. To overcome this limitation, parallelized PA signal acquisition can be used for which FP sensors with uniform optical thickness are required. In this work, the optical thickness is tuned a) irreversibly through the use of a photopolymer host matrix and b) actively using embedded electro-optic (EO) chromophores. Polymer spacers (5 μm) were deposited using spin coating and sandwiched between two dielectric mirrors and transparent ITO electrodes. The employed polymer guest-host system consists of an EO chromophore (2-methyl-4-nitroaniline) and poly(vinyl cinnamate). EO tuneability was induced using contact poling and a tuneability of 68 pm was demonstrated. The optical thickness was homogenised by raster scanning a UV beam whilst varying the exposure time across a 4 mm2 detection aperture. Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13769 SN - 1996-756X PB - Society of Photo-Optical Instrumentation Engineers (SPIE) ER - TY - GEN A1 - Richter, Asta A1 - Brzezinka, Klaus-Werner T1 - Thin Film Deposition and Modification of Fullerenes by Laser Radiation T2 - Wissenschaftliche Beiträge 1/1995 N2 - Laser ablation from solid fullerene pellet and textured graphite targets has been probed for deposition of thin fullerite and diamond-like carbon (DLC) films by means of a pulsed C02 laser. Ablation of fullerene material does not yield fullerite films, but results in amorphous pregraphitic carbon structures. At very low laser flux structural transformations are observed with increasing exposure time. These thermal effects cannot completely decompose the fullerenes without increase of the laser power density. Thermal evaporation is a suitable method to deposite fullerite fllms of high quality, thus epitaxial fullerite films are grown on mica. Sandwich C60/DLC structures are produced by laser deposition which show a sharp interface as can be deduced from the superposition of the characteristic Raman spectra of the fullerite and the DLC. N2 - Mit einem gepulsten CO2-Laser wird Laserablation von festen Fullerene-Pellets und texturierten Graphittargets zur Abscheidung von dünnen Fullerite- und diamantartigen Kohlenstoffilmen (DLC) getestet. Ablation von Fullerene-Material ist nicht zur Bildung von Fullerite-Filmen geeignet, sondern es entstehen amorphe pregraphitische Kohlenstoffstrukturen. Schäden, die durch die Einwirkung des Lasers auf Fullerene verursacht werden, wurden mittels Ramanspektroskopie untersucht. Bei geringen Laserleistungsdichten werden Strukturänderungen mit wachsender Einwirkungszeit des Lasers beobachtet. Diese thermischen Effekte können das Fullerene-Material nicht vollständig umwandeln, ohne daß die Laserleistungsdichte erhöht wird. Thermische Verdampfung ist eine geeignete Methode, um Fullerite-Schichten guter Qualität abzuscheiden: so konnten epitaktische Filme auf Glimmer aufwachsen. C60/DLC-Sandwich-Strukturen werden durch Laserabscheidung hergestellt und zeigen scharfe Grenzflächen, wie aus der definierten Überlagerung der charakteristischen Ramanspektren des Fullerite- und DLC-Films abgeleitet werden kann. Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-8118 SN - 0949-8214 VL - 1 IS - 1 SP - 100 EP - 103 ER - TY - GEN A1 - Krechlok, Kurt T1 - Struktur und Zwanglauf bei mechanischen Getrieben T2 - Wissenschaftliche Beiträge 1/1996 N2 - In vielen Maschinen und Geräten bilden komplexe Bewegungsabläufe einzelner Arbeitsorgane und deren Zusammenspiel das Kernstück für die Erfüllung der geforderten technischen Funktion. Die technisch-wirtschaftlich optimale Realisierung von Bewegungsabläufen und die Beherrschung ihrer Dynamik sind damit oft entscheidende Voraussetzungen für den Erfolg des Gesamtproduktes. Typische Beispiele dafür sind Maschinen zur Herstellung und Verarbeitung von Textilien, Druck- und Papiermaschinen, Verpackungsmaschinen aller Art sowie Handhabungseinrichtungen, Fördereinrichtungen und Industrieroboter. Zur mechanischen Lösung solcher Bewegungsaufgaben dienen die ungleichmäßig übersetzenden Kurven- und Gelenkgetriebe, die in vielfältigen Bauformen und Kombinationen mit oft geringem Aufwand sicher und zuverlässig präzise Bewegungsabläufe erzeugen, und das auch bei hohen Geschwindigkeiten und Kräften. In nachfolgenden Ausführungen sollen einige Zusammenhänge zwischen der Getriebestruktur und dem zwangsläufigen Bewegungsablauf mechanischer Getriebe beschrieben werden. Y1 - 1996 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-8213 SN - 0949-8214 VL - 2 IS - 1 SP - 54 EP - 56 ER - TY - INPR A1 - Richter, Asta A1 - Anwand, Wolfgang A1 - Chen, Chun-Liang A1 - Böttger, Roman T1 - Evaluation of defect formation in helium irradiated Y2O3 doped W-Ti alloys by positron annihilation and nanoindentation T2 - Journal of Nuclear Materials N2 - Helium implanted tungsten-titanium ODS alloys are investigated using positron annihilation spectroscopy and nanoindentation. Titanium reduces the brittleness of the tungsten alloy, which is manufactured by mechanical alloying. The addition of Y2O3 nanoparticles increases the mechanical properties at elevated temperature and enhances irradiation resistance. Helium ion implantation was applied to simulate irradiation effects on these materials. The irradiation was performed using a 500 kV He ion implanter at fluences around 5 × 1015 cm−2 for a series of samples both at room temperature and at 600 °C. The microstructure and mechanical properties of the pristine and irradiated W-Ti-ODS alloy are compared with respect to the titanium and Y2O3 content. Radiation damage is studied by positron annihilation spectroscopy analyzing the lifetime and the Doppler broadening. Three types of helium-vacancy defects were detected after helium irradiation in the W-Ti-ODS alloy: small defects with high helium-to-vacancy ratio (low S parameter) for room temperature irradiation, larger open volume defects with low helium-to-vacancy ratio (high S parameter) at the surface and He-vacancy complexes pinned at nanoparticles deeper in the material for implantation at 600 °C. Defect induced hardness was studied by nanoindentation. A drastic hardness increase is observed after He ion irradiation both for room temperature and elevated irradiation temperature of 600 °C. The Ti alloyed tungsten-ODS is more affected by the hardness increase after irradiation compared to the pure W-ODS alloy. KW - W-Ti-ODS alloy KW - He implantation KW - positron annihilation spectroscopy KW - nanoindentation KW - vacancy defect Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-10048 ER - TY - JOUR A1 - Bondarenko, Siegfried A1 - Hülsemann, Marcel A1 - Mai, Andreas A1 - Steglich, Patrick T1 - Fiber-to-chip light coupling using a graded-index lensed fiber collimator JF - Optical Engineering N2 - Fiber-to-chip light coupling using a graded-index (GRIN) fiber collimator is investigated. Our experiments with grating couplers and strip waveguides fabricated in a photonic integrated circuit technology reveal that the peak coupling efficiency of a GRIN fiber collimator is 7.8 dB lower than that of a single-mode fiber. However, the 3-dB alignment tolerance is improved by a factor of about 5.7 giving rise to pluggable sensor solutions. This work opens a path toward a cost-effective and portable sensor platform based on pluggable photonic biosensors using GRIN fiber collimators. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13749 SN - 1560-2303 VL - 60 IS - 1 PB - SPIE ER - TY - CHAP A1 - van de Sand, Ron A1 - Corasaniti, Sandra A1 - Reiff-Stephan, Jörg T1 - Review of Condition Based Maintenance approaches for vapor compression refrigeration systems T2 - Conference Proceedings : 1st German-West African Conference on Sustainable, Renewable Energy Systems SusRes : 1st July 2020 - Kara, Togo N2 - Vapor compression refrigeration systems are subject to performance degradation over time due to the presence of faults. However, latest work in the field of condition-based maintenance shows promising results in the automatic early detection of anomalous behaviour as well as in accurate machine diagnostics and can, therefore, increase the overall system reliability by simultaneously preventing machine downtimes. In this paper, the latest research works carried out within the last decade are reviewed and the approaches are classified regarding their working principles. Furthermore, the work at hand depicts the current research trend in this field and outlines current obstacles. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13369 SP - 24 EP - 33 ER - TY - CHAP A1 - Dable, Etienne T1 - Construction of PV Systems for Elementary Schools in the Savannah of Togo BT - Light for Education and Culture T2 - Conference Proceedings : 1st German-West African Conference on Sustainable, Renewable Energy Systems SusRes : 1st July 2020 - Kara, Togo N2 - The savannah region in northern Togo borders on Ghana, Burkina Faso and Benin (Figure 1). It covers 8,596 km2, which is 15% of the total area of Togo. The regional capital Dapaong has about 100,000 inhabitants. The savannah region consists of 5 prefectures, 70 cantons, 1,073 villages and 451 hamlets. The number of inhabitants is growing rapidly. The population figures were 828,224 in 2010 and 890,403 in 2013, a growth rate of 8.2% in only 3 years. With 105 inhabitants per km2 the savannah region is more densely populated than German Mecklenburg-Vorpommern (69 inhabitants per km2). The savannah region is the poorest region in the country. In the villages, subsistence farming prevails. Surpluses are sold at village markets or nearby city markets with little profit, since raw products are rarely processed and certainly not processed and the purchasing power in the region is low. The sensitive savannah floors are overused. During the long dry season (October to May) there is a lack of artificial irrigation. The climate change affects the savannah region through shorter and irregular rainy seasons. Deforestation leads to further drying out of the soil. The population is increasing, becoming poorer and poorer and uses almost exclusively wood for cooking in the villages. This leads to further deterioration of the arable land. Harvest yields are falling because improved seeds and fertilisers are also lacking. The infrastructure in the region is at an extremely low level. There are no industrial enterprises in the savannah region. There is an almost complete lack of companies that process and refine agricultural products. There is a lack of storage facilities and cold chains for agricultural products. Only for wood and charcoal there are transport routes from the international highway to regions with better purchasing power. A major obstacle to the establishment of small businesses is the lack of electricity. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13415 SP - 111 EP - 115 ER - TY - CHAP A1 - Lisker, Roberto A1 - Nowitzki, Mario A1 - Hellwig, Udo A1 - Wildenauer, Franz-Xaver T1 - Comparable numerical study on different working fluids for micro scale power cycle integrated into a pellet fired boiler BT - Numerical Simulation of the Tesla Turbine Efficiency T2 - Conference Proceedings : 1st German-West African Conference on Sustainable, Renewable Energy Systems SusRes : 1st July 2020 - Kara, Togo N2 - A cost-effective power cycle shall be developed to supply heat and electricity (co-generation). The aim of this study is to find an appropriate power cycle and working fluid for a friction turbine application. Due to its low production costs, better scalability and low-maintenance requirements, a friction turbine, also known as Tesla turbine, shall be used. In order to find a proper working fluid and estimate the efficiency and power output,a numerical study was performed on five promising working fluids namely Xenon, Argon, Helium, Air and superheated Steam. The simulation model consists of three disks with a diameter of 0,25 m and an outlet diameter of 0,12 mm rotating at constant 10.000 rpm.It is tried to keep the Gap Reynolds number at a constant 73, to ensure a laminar flow regime between the disks. The outcome of the numerical study showed that all working fluids are suitable. The highest efficiency (shaft power / technical power) has been achieved with steam (96%) and a power output of 126 W/gap. The least efficiency with 89% has been realized with air and a Power output of 118 W/gap. The noble gases are in between these fluids. By comparing the simulation data and taken into account numerical and estimation errors,all five working fluids are at par. Thus, the choice of the working fluid and the power cycle is an economical. While a hot gas air turbine is not as efficient as the steam turbine, the invest and maintenance costs are lower due to less heat exchangers and necessaries like water reconditioningand a phase separator. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13383 SP - 73 EP - 80 ER - TY - JOUR A1 - Ksianzou, Viachaslau A1 - Velagapudi, R. K. A1 - Grimm, Bernd A1 - Schrader, Sigurd T1 - Polarization-dependent optical characterization of poly(phenylquinoxaline) thin films JF - Journal of Applied Physics N2 - Linear optical properties of two types of poly(phenylquinoxaline) (PPQ) are studied by multiwavelength prism coupling technique and optical absorption spectroscopy. Surface roughness measurements are done using atomic force microscopy. PPQs form smooth films of high optical quality having refractive indices above 1.7 in the visible and near infrared spectral ranges. Enhanced birefringence of Δn∼0.04Δn∼0.04 has been observed in both PPQ films prepared by spin coating. Sellmeier coefficients are derived for the wavelength range starting from 0.532to1.064μm0.532to1.064μm for both TE and TM polarizations. Quantum chemical calculations both on the semiempirical and on the ab initio level are carried out in order to calculate the first-order molecular polarizability tensors of the polymer repeat units. From the obtained tensor elements, theoretical values for both the average refractive indices and the maximum expectable birefringence are calculated. Based on these values a more detailed interpretation of the experimental findings is carried out. The dispersion of refractive index is quantified by the value of Abbe’s constant (νd)(νd). In our case the value νd≈11νd≈11 indicates high dispersion in the visible spectral range. The imaginary part kk of the complex refractive index n∗=n−ikn*=n−ik reaches values of k⩽10−3k⩽10−3 in the wavelength range from 0.5to1μm0.5to1μm. Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-9761 SN - 1089-7550 VL - 100 IS - 6 ER - TY - JOUR A1 - Yeshchenko, Oleg A. A1 - Dmitruk, Igor M. A1 - Grytsenko, Kostyantyn A1 - Prokopets, Vadym M. A1 - Kotko, Andriy V. A1 - Schrader, Sigurd T1 - Influence of interparticle interaction on melting of gold nanoparticles in Au/polytetrafluoroethylene nanocomposites JF - Journal of Applied Physics N2 - The temperature dependence of the surface plasmon resonance energy and width in 5 nm spherical gold nanoparticles embedded in a polymer polytetrafluoroethylene matrix has been studied using absorption spectroscopy. The jumplike features have been observed in these dependences indicating the melting of gold nanoparticles at temperatures considerably lower than the bulk melting point. The interaction between gold nanoparticles sufficiently affects the melting of nanoparticles. The increase in the filling factor of the particles leads to a decrease in the melting temperature of gold nanoparticles. Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-9759 SN - 1089-7550 VL - 105 IS - 9 ER - TY - CHAP A1 - Richter, Asta A1 - Ries, Ronald T1 - Mechanical properties of fullerite and diamondlike carbon films using surface acoustic waves and nanoindentation T2 - Proc. SPIE 3725, International Conference on Solid State Crystals '98: Epilayers and Heterostructures in Optoelectronics and Semiconductor Technology, (8 April 1999) N2 - C60 and amorphous diamond-like carbon (DLC) films have been grown by thermal evaporation and laser ablation techniques at different substrate temperatures and on various substrates. The elastic modulus and the hardness of the films have been investigated by surface acoustic waves and nanoindentation. Both methods are completely new and designed for investigations of very thin films. For homogeneous C60 films the Young's modulus was found to be 14 GPa and the Poisson's ratio of 0.2. The measured nanohardness of 167 MPa corresponds with the microhardness value of 130 MPa. There is a correlation between deposition techniques and hardness as well as Young's modulus for DLC films. KW - morphous carbon film KW - C film KW - deposition technique KW - scanning force microscopy KW - nanoindentation KW - surface acoustic wave KW - Young's modulus Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-14840 SP - 94 EP - 101 ER - TY - JOUR A1 - Fünning, Tabea A1 - Paul, Martin A1 - Manganelli, Costanza Lucia A1 - Wenger, Christian A1 - Mai, Andreas A1 - Steglich, Patrick T1 - Comparative simulation analysis of photonic ultrasound sensors based on silicon waveguides JF - Scientific Reports N2 - Pressure sensors based on photonic integrated circuits (PIC) offer the prospect of outstanding sensitivities, extreme miniaturization and have the potential for highly scalable production using CMOS compatible processing. PIC-based pressure sensors detect the change in optical properties, i.e. the intensity or phase of the optical carrier wave inside miniaturized waveguide structures. The detection of ultrasound is achieved by engineering the waveguide architecture such that a pressure causes a high change in the effective refractive index of the waveguide. A range of PIC-based pressure sensors have been reported, but a comparison of the sensitivity of the different approaches is not straightforward, since different pressure sensitive waveguide architectures as well as photonic layouts and measurement setups impact the performance. Additionally, the used sensitivity unit is not uniform throughout the different studies, further complicating a comparison. In this work, a detailed simulation study is carried out by finite element modeling of different pressure sensitive waveguide architectures for a consistent comparison. We analyze three different sensor architectures: (A) a free standing membrane located within a tiny air gap above the waveguide, (B) a waveguide located on top of a deflectable membrane as well as (C) a waveguide embedded inside a pressure-sensitive polymer cladding. The mechanical response of the structures and the resulting changes in mode propagation, i.e. the change of the effective refractive index, are analyzed. The waveguide sensitivities in RIU/MPa for different waveguide types (strip, slot) and polarization states (TE, TM) are compared. The results reveal inherent limitations of the different waveguide designs and create a basis for the selection of suitable designs for further ultrasound sensor development. Possibilities for enhancing waveguide sensitivity are identified and discussed. Additionally, we have shown that the studied approaches are extensible to SiN waveguides. Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-20560 VL - 15 PB - Springer Nature ER - TY - CHAP A1 - Bauer, Joachim A1 - Heinrich, Friedhelm A1 - Fursenko, Oksana A1 - Marschmeyer, Steffen A1 - Bluemich, Adrian A1 - Pulwer, Silvio A1 - Steglich, Patrick A1 - Villringer, Claus A1 - Mai, Andreas A1 - Schrader, Sigurd T1 - Very high aspect ratio through silicon via reflectometry T2 - Proceedings of SPIE N2 - Through Silicon Via (TSV) technology is a key feature of new 3D integration of circuits by creation of interconnections using vias, which go through the silicon wafer. Typically, the highly-selective Bosch Si etch process, characterized by a high etch rate and high aspect ratio and forming of scallops on the sidewalls is used. As presented in this paper, we have developed an experimental setup and a respective evaluation algorithm for the control and monitoring of very high aspect ratio TSV profiles by spectroscopic reflectometry. For this purpose square via arrays with lateral dimension from 3 to 10 μm were fabricated by a Bosch etch process and analyzed by our setup. By exploiting interference and diffraction effects of waves reflected from the top and bottom surfaces as well as from the side walls of the TSV patterns, the measurements provided etch depths, CD values and scallop periods. The results were compared with data obtained by a commercial wafer metrology tool. Aspect ratios of up to 35:1 were safely evaluable by our setup. Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13758 SN - 1996-756X ER - TY - GEN A1 - Gündel, Harald A1 - Volkmann, Hans T1 - Eximerlaser mit gauß-förmigem Strahlprofil T2 - Wissenschaftliche Beiträge 1/1996 N2 - Wegen ihrer Wellenlänge im ultravioletten Spektralgebiet gehören Eximerlaser (z. B. KrF, ArF, XeCI) zu den am vielseitigsten eingesetzten Lasern in der Forschung und zunehmend auch in der industriellen Anwendung. Alle am Markt erhältlichen Excimer-Laser weisen jedoch einen wesentlichen Nachteil auf, der ihre Einsatzmöglichkeiten begrenzt. Bedingt durch konstruktive Besonderheiten ist ihre Strahlqualität unbefriedigend. Sie weisen einen rechteckförmigen Strahlquerschnitt auf mit einem komplizierten Gemisch verschiedener transversaler Moden (Multimodenstruktur). Diese Eigenschaft wirkt sich negativ auf die Fokussierbarkeit der Strahlung aus, wodurch der positive Einfluß der kurzen Wellenlängen z.T. wieder zunichte gemacht wird. Besonders störend ist dieser Effekt z. B. beim Bohren feinster Löcher oder beim Einkoppeln der Strahlung in Lichtleiter. Das Ziel der Arbeiten besteht daher darin, einen Eximerlaser zu entwickeln, der die Vorteile der kurzen Wellenlänge mit einer guten Strahlqualität verbindet. Anzustreben ist ein kreisrunder Strahlquerschnitt mit nur einer Strahlungsmode und Gauß-Profil. Dabei sollen die Erfahrungen genutzt werden, die im Institut für Plasma- und Lasertechnik der TFH Wildau bei der Entwicklung von Stickstofflasern mit gauß-ähnlichem Strahlprofil gewonnen wurden. Ein solches Gerät würde die Einsatzgebiete von Eximer-Lasern erweitern und hätte voraussichtlich gute Marktchancen. Y1 - 1996 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-8245 SN - 0949-8214 VL - 2 IS - 1 SP - 68 EP - 71 ER - TY - CHAP A1 - Reiff-Stephan, Jörg T1 - Solar power in product development T2 - Conference Proceedings : 1st German-West African Conference on Sustainable, Renewable Energy Systems SusRes : 1st July 2020 - Kara, Togo N2 - The availability of electrical energy is one of the essential basic elements for economic growth and humanitarian living conditions. In one of the poorest regions of Western Africa - in the savannah region of northern Togo - the central expansion of electricity grids has not taken place. Decentralized solutions based on renewable energy systems can help here and promote the region's development. In the presented paper, the various renewable energy carrier systems were examined with regard to their use in the savannah region of Western Africa. The solar energy carrier system could be used as a power supplier in the secondary conversion process to mechanical power. Subsequently, a prototype for a clay brick production machine was designed and a digital mock-up was developed. Together with the partners in Togo, the prototype is built and tested in the field. Experiences are being gathered in cooperation with Bonita-Haus and will be incorporated into the educational content in Togo as well as at the Technical University of Wildau. This will make a significant contribution to the utilization of the technology at the site and to improving the living conditions in Western Africa. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13206 SP - 55 EP - 65 ER - TY - GEN A1 - Beyer, Harald A1 - Harendt, Andreas A1 - Huget, Karin A1 - Koschlig, Tobias A1 - Rolle, Siegfried A1 - Ross, Werner A1 - Volkmann, Hans T1 - Das Institut für Plasma- und Lasertechnik an der TFH Wildau - Entwicklung und Kooperation mit anderen Einrichtungen T2 - Wissenschaftliche Beiträge 2001 N2 - Die Plasmatechnik gehört mittlerweile zu den Schlüsseltechnologien des nachhaltigen Wachstums und der Bewältigung des Strukturwandels der deutschen Wirtschaft. Plasmaverfahren sind zur Voraussetzung für die Herstellung von Chips für Hochleistungscomputer geworden. Mit Plasmatechnologien werden Werkstoffoberflächen veredelt und Materialien mit neuen Eigenschaften erzeugt. Es gibt Plasmalampen, die ohne Verwendung von Quecksilber hohe Lichtausbeuten und gute Farbwiedergabe erreichen. Auch bei der Entsorgung toxischer Stoffe und von Abfällen kommen Plasmatechnologien zum Einsatz. Das Bundesministerium für Bildung und Forschung (BMBF) hat in einer Broschüre die Anwendung und Forschung auf dem Gebiet der Plasmatechnik in Deutschland zusammengestellt. In Deutschland wird jährlich eine Industrieproduktion von 45 Mio. € durch die Plasmatechnologie erst ermöglicht. Vor diesem Hintergrund soll die Entwicklung der Forschung und Ausbildung auf dem Gebiet der Plasmatechnik an der TFH Wildau beschrieben werden. Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-8518 SN - 0949-8214 VL - 6 SP - 38 EP - 41 ER -