Kischkat J.,Humboldt University of Berlin |
Peters S.,Sentech Instruments GmbH |
Gruska B.,Sentech Instruments GmbH |
Semtsiv M.,Humboldt University of Berlin |
And 8 more authors.
Applied Optics | Year: 2012
The complex refractive index components, n and k, have been studied for thin films of several common dielectric materials with a low to medium refractive index as functions of wavelength and stoichiometry for mid-infrared (MIR) wavelengths within the range 1.54-14.29 μm (700-6500 cm-1). The materials silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, and titanium oxide are prepared using room temperature reactive sputter deposition and are characterized using MIR variable angle spectroscopic ellipsometry. The investigation shows how sensitive the refractive index functions are to the O2 and N2 flow rates, and for which growth conditions the materials deposit homogeneously. It also allows conclusions to be drawn on the degree of amorphousness and roughness. To facilitate comparison of the materials deposited in this work with others, the index of refraction was also determined and provided for the near-IR and visible ranges of the spectrum. The results presented here should serve as a useful information base for designing optical coatings for the MIR part of the electromagnetic spectrum. The results are parameterized to allow them to be easily used for coating design. © 2012 Optical Society of America.
Greiner F.,University of Kiel |
Carstensen J.,University of Kiel |
Kohler N.,University of Kiel |
Pilch I.,Linköping University |
And 3 more authors.
Plasma Sources Science and Technology | Year: 2012
For the in situ analysis of nano-sized particles in a laboratory plasma, Mie ellipsometry is a well established technique. We present a simple setup with two CCD cameras to gain online spatiotemporal resolved information of the growth dynamics of particles which are produced by plasma chemical processes in an argon-acetylene plasma. Imaging Mie ellipsometry proves to be a powerful technique to study the growth processes of nanodust in all its details. © 2012 IOP Publishing Ltd.
Rademacher D.,Fraunhofer Institute for Surface Engineering and Thin Films |
Vergohl M.,Fraunhofer Institute for Surface Engineering and Thin Films |
Richter U.,Sentech Instruments GmbH
Applied Optics | Year: 2011
An in situ monitoring setup and process control loop were developed and integrated into a magnetron sputtering coater equipped with a Sentech SE 401 single wavelength ellipsometer, including the engineering of software for in situ process control to enhance production accuracy. By using that software, the system allows direct monitoring of the layer thickness on a moving substrate. It is shown that it is possible to determine the complex index of refraction from the distribution of measurements depending on the layer thickness. A strategy has been developed for in situ reverse thickness engineering of the top layers to compensate measurement errors. © 2011 Optical Society of America.
Haeberle J.,TU Brandenburg |
Henkel K.,TU Brandenburg |
Gargouri H.,Sentech Instruments GmbH |
Naumann F.,Sentech Instruments GmbH |
And 4 more authors.
Beilstein Journal of Nanotechnology | Year: 2013
We report on results on the preparation of thin (<100 nm) aluminum oxide (Al2O3) films on silicon substrates using thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) in the SENTECH SI ALD LL system. The T-ALD Al2O3 layers were deposited at 200 °C, for the PE-ALD films we varied the substrate temperature range between room temperature (rt) and 200 °C. We show data from spectroscopic ellipsometry (thickness, refractive index, growth rate) over 4" wafers and correlate them to X-ray photoelectron spectroscopy (XPS) results. The 200 °C T-ALD and PE-ALD processes yield films with similar refractive indices and with oxygen to aluminum elemental ratios very close to the stoichiometric value of 1.5. However, in both also fragments of the precursor are integrated into the film. The PE-ALD films show an increased growth rate and lower carbon contaminations. Reducing the deposition temperature down to rt leads to a higher content of carbon and CH-species. We also find a decrease of the refractive index and of the oxygen to aluminum elemental ratio as well as an increase of the growth rate whereas the homogeneity of the film growth is not influenced significantly. Initial state energy shifts in all PE-ALD samples are observed which we attribute to a net negative charge within the films. © 2013 Haeberle et al; licensee Beilstein-Institut.
Porteanu H.E.,Ferdinand - Braun - Institute |
Gesche R.,Ferdinand - Braun - Institute |
Wandel K.,Sentech Instruments GmbH
Plasma Sources Science and Technology | Year: 2013
A miniature double plasma jet source driven at microwave frequencies (∼2.45 GHz) was developed and analyzed. The source consists of a copper resonator (screened within an aluminum housing) that excites plasma simultaneously in two alumina tubes of 5 mm internal diameter. Field and plasma simulations were performed using the software Comsol. Assuming a homogeneous electron distribution we calculate the plasma impedance as a function of its conductivity. The electron density and the plasma conductivity are estimated as a function of the absorbed power in plasma for argon and oxygen. Experimentally it was shown that the microwave energy is coupled into oxygen plasma with an efficiency of >85% and into argon plasma with ∼30%. The source efficiently produces atomic oxygen and nitrogen as is demonstrated by plasma-enhanced atomic layer deposition. Finally, the time evolution during ignition, the transition from low efficient capacitive to highly efficient inductive coupling, the free electron distribution as a function of time and other parameters are analyzed. © 2013 IOP Publishing Ltd.
Foest R.,Leibniz Institute for Plasma Science and Technology |
Schmidt M.,Leibniz Institute for Plasma Science and Technology |
Gargouri H.,Sentech Instruments GmbH
European Physical Journal D | Year: 2014
Effects of spatial ordering of molecules on surfaces are commonly utilized to deposit ultra-thin films with a thickness of a few nm. In this review paper, several methods are discussed, that are distinguished from other thin film deposition processes by exactly these effects that lead to self-assembling and self-limiting layer growth and eventually to coatings with unique and fascinating properties and applications in micro-electronics, optics, chemistry, or biology. Traditional methods for the formation of self-assembled films of ordered organic molecules, such as the Langmuir-Blodgett technique along with thermal atomic layer deposition (ALD) of inorganic molecules are evaluated. The overview is complemented by more recent developments for the deposition of organic or hybrid films by molecular layer deposition. Particular attention is given to plasma assisted techniques, either as a preparative, supplementary step or as inherent part of the deposition as in plasma enhanced ALD or plasma assisted, repeated grafting deposition. The different methods are compared and their film formation mechanisms along with their advantages are presented from the perspective of a plasma scientist. The paper contains lists of established film compounds and a collection of the relevant literature is provided for further reading. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
Auinger M.,Max Planck Institute Für Eisenforschung |
Ebbinghaus P.,Max Planck Institute Für Eisenforschung |
Blumich A.,SENTECH Instruments GmbH |
Erbe A.,Max Planck Institute Für Eisenforschung
Journal of the European Optical Society | Year: 2014
Heating by absorption of light is a commonly used technique to ensure a fast temperature increase of metallic samples. The rate of heating when using optical heating depends critically on the absorption of light by a sample. Here, the reflection and scattering of light from UV to IR by surfaces with different roughness of iron-based alloy samples (Fe, 1 wt-% Cr) is investigated. A combination of ellipsometric and optical scattering measurements is used to derive a simplified parametrisation which can be used to obtain the absorption of light from random rough metal surfaces, as prepared through conventional grinding and polishing techniques. By modelling the ellipsometric data of the flattest sample, the pseudodielectric function of the base material is derived. Describing an increased roughness by a Maxwell-Garnett model does not yield a reflectivity which follows the experimentally observed sum of scattered and reflected intensities. Therefore, a simple approach is introduced, based on multiple reflections, where the number of reflections depends on the surface roughness. This approach describes the data well, and is subsequently used to estimate the fraction of absorbed energy. Using numerical modelling, the effect on the heating rate is investigated. A numerical example is analysed, which shows that slight changes in roughness may result in big differences of the energy input into a metallic sample, with consequences on the achieved temperatures. Though the model oversimplifies reality, it provides a physically intuitive approach to estimate trends. © The Authors. All rights reserved.
Lieten R.R.,Catholic University of Leuven |
Lieten R.R.,IMEC |
Seo J.W.,Catholic University of Leuven |
Decoster S.,Catholic University of Leuven |
And 6 more authors.
Applied Physics Letters | Year: 2013
We demonstrate single crystalline GeSn with tensile strain on silicon substrates. Amorphous GeSn layers are obtained by limiting the adatom surface mobility during deposition. Subsequent annealing transforms the amorphous layer into single crystalline GeSn by solid phase epitaxy. Excellent structural quality is demonstrated for layers with up to 6.1% of Sn. The GeSn layers show tensile strain (up to +0.34%), which lowers the difference between direct and indirect band transition and makes this method promising for obtaining direct band gap group IV layers. GeSn with 4.5% Sn shows increased optical absorption compared to Ge and an optical band gap of 0.52 eV. © 2013 American Institute of Physics.
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: NMP-2008-2.2-2 | Award Amount: 4.52M | Year: 2009
Three-dimensional large area metamaterials, especially Negative Index Materials (NIMs) promise to enable numerous novel and breakthrough applications like perfect lenses and cloaking devices, not only but especially if they exhibit the desired properties in the visible frequency range. For the European Photonics industry it is of paramount importance enabling fabricating such materials as soon as possible, to maintain its important position in the areas of optical components and systems as well as production technologies. Till now such materials have not been produced, yet - neither in 3D nor on large areas, let alone both combined. The aim of NIM_NIL is the development of a production process for 3D NIMs in the visible regime combining UV-based Nanoimprint Lithography (UV-NIL) on wafer scale using the new material graphene and innovative geometrical designs. This project will go beyond state-of-the-art in three important topics regarding NIMs: the design, the fabrication using Nanoimprintlithography (NIL) and the optical characterization by ellipsometry. New designs and the new material Graphene will be investigated to extend the existing frequency limit of 900 nm into the visible regime. The fabrication method of choice is UV-NIL since it allows cost efficient large area nanostructuring, which is indispensible if materials like NIMs should be produced on large scale. The negative refraction will be measured using ellipsometry which is a fast and non-destructive method to control the fabrication process. At the end of the project a micro-optical prism made from NIM will be fabricated to directly verify and demonstrate the negative refractive index. Each aspect of innovation within NIM_NIL design, fabrication and characterisation of NIMs is represented by experts in this field resulting in a multidisciplinary highly motivated consortium containing participants from basic research as well as industrial endusers from whole Europe.
Agency: European Commission | Branch: FP7 | Program: BSG-SME | Phase: SME-2013-1 | Award Amount: 1.42M | Year: 2013
With the fast development of applications based on smart and miniaturized sensors in aerospace, medical or automotive domains, requirements on electronic modules are more and more linked to size, stability, reliability and performances. Capacitors are key components of electronic modules to deliver power with the right voltages to different functions from a single power source (such as a battery) or to protect them against voltage jumps. IPDiA has developed for many years a technology of integrated capacitors (called PICS) which overcomes current technologies (e.g. tantalum capacities) and which can be a solution to build highly integrated and high performances electronic modules. The goal of the PICS project is to go further and to bring a technological gap to get higher densities of capacitors and higher breakdown voltage. It will open the way to new markets by offering even more integration level and miniaturization (in order to increase the functionality combination and the complexity within a single package) and higher performances (in order to ensure long life operations and be able to place the sensors as close as possible to the hottest areas for efficient monitoring). The innovation will be based on the use of a specific technology called atomic layer deposition, or ALD, that will enable to obtain an impressive quality of dielectric. Besides technical goals, the PICS project aims also to set-up a cost effective industrial solution. Three SMEs, IPDiA, Sentech and Picosun, join forces with two research institutes, Fraunhofer and CEA, to response to these challenges. The first targeted markets are the high-end integrated capacitors for medical applications and the future DRAM market.