TY - CHAP A1 - Hammerschmidt, Martin A1 - Lockau, Daniel A1 - Burger, Sven A1 - Schmidt, Frank A1 - Schwanke, Christoph A1 - Kirner, Simon A1 - Calnan, Sonya A1 - Stannowski, Bernd A1 - Rech, Bernd T1 - 3D optical modeling of thin-film a-Si/mc-Si tandem solar cells with random textured interfaces using FEM T2 - Renewable Energy and the Environment Optics and Photonics Congress Y1 - 2012 U6 - https://doi.org/10.1364/E2.2012.JM5A.15 SP - JM5A.15 PB - Optical Society of America ER - TY - JOUR A1 - Hammerschmidt, Martin A1 - Lockau, Daniel A1 - Burger, Sven A1 - Schmidt, Frank A1 - Schwanke, Christoph A1 - Kirner, Simon A1 - Calnan, Sonya A1 - Stannowski, Bernd A1 - Rech, Bernd T1 - FEM-based optical modeling of silicon thin-film tandem solar cells with randomly textured interfaces in 3D JF - Proc. SPIE Y1 - 2013 U6 - https://doi.org/10.1117/12.2001789 VL - 8620 SP - 86201H ER - TY - CHAP A1 - Zschiedrich, Lin A1 - Greiner, Horst A1 - Pomplun, Jan A1 - Hammerschmidt, Martin A1 - Burger, Sven A1 - Schmidt, Frank T1 - FEM simulations of light extraction from nanostructured organic light-emitting diodes T2 - Renewable Energy and the Environment Optics and Photonics Congress Y1 - 2012 U6 - https://doi.org/10.1364/SOLED.2012.LT2B.5 SP - LT2B.5 PB - Optical Society of America ER - TY - JOUR A1 - Becker, Christiane A1 - Wyss, Philippe A1 - Eisenhauer, David A1 - Probst, Jürgen A1 - Preidel, Veit A1 - Hammerschmidt, Martin A1 - Burger, Sven T1 - 5 x 5 cm2 silicon photonic crystal slabs on glass and plastic foil exhibiting broadband absorption and high-intensity near-fields JF - Sci. Rep. Y1 - 2014 U6 - https://doi.org/10.1038/srep05886 VL - 4 SP - 5886 ER - TY - JOUR A1 - Barth, Carlo A1 - Roder, Sebastian A1 - Brodoceanu, Daniel A1 - Kraus, Tobias A1 - Hammerschmidt, Martin A1 - Burger, Sven A1 - Becker, Christiane T1 - Increased fluorescence of PbS quantum dots in photonic crystals by excitation enhancement JF - Appl. Phys. Lett. Y1 - 2017 U6 - https://doi.org/10.1063/1.4995229 VL - 111 SP - 031111 ER - TY - JOUR A1 - Hammerschmidt, Martin A1 - Weiser, Martin A1 - Santiago, Xavier Garcia A1 - Zschiedrich, Lin A1 - Bodermann, Bernd A1 - Burger, Sven T1 - Quantifying parameter uncertainties in optical scatterometry using Bayesian inversion JF - Proc. SPIE Y1 - 2017 U6 - https://doi.org/10.1117/12.2270596 VL - 10330 SP - 1033004 ER - TY - JOUR A1 - Jäger, Klaus A1 - Köppel, Grit A1 - Eisenhauer, David A1 - Chen, Duote A1 - Hammerschmidt, Martin A1 - Burger, Sven A1 - Becker, Christiane T1 - Optical simulations of advanced light management for liquid-phase crystallized silicon thin-film solar cells JF - Proc. SPIE Y1 - 2017 U6 - https://doi.org/10.1117/12.2273994 VL - 10356 SP - 103560F ER - TY - JOUR A1 - Gutsche, Philipp A1 - Poulikakos, Lisa A1 - Hammerschmidt, Martin A1 - Burger, Sven A1 - Schmidt, Frank T1 - Time-harmonic optical chirality in inhomogeneous space JF - Proc. SPIE Y1 - 2016 U6 - https://doi.org/10.1117/12.2209551 VL - 9756 SP - 97560X ER - TY - GEN A1 - Gutsche, Philipp A1 - Poulikakos, Lisa A1 - Burger, Sven A1 - Hammerschmidt, Martin A1 - Schmidt, Frank T1 - Optical chirality: conservation law in arbitrary space T2 - 606. WE-Heraeus-Seminar on Nanophotonics and Complex Spatial Modes of Light N2 - The introduction of the near-field quantity of optical chirality has emerged in various numerical and few experimental studies of local chirality enhancement due to its relation to the excitation rate of chiral molecules. This time-even pseudoscalar has been dismissed as being a higher-order version of helicity. Nevertheless, we revisit the derivation of the underlying conservation law and define optical chirality in media similar to. We identify the mechanism of chirality conversion by either inhomogeneous or anisotropic space to complement the conservation of optical chirality. The conservation law of optical chirality in arbitrary space enables the extension of the concept of polarization to the near-field where no distiniguished propagation direction of light is present. We show that the connection of electromagnetic energy and optical chirality provide the ability to define a circular polarization basis in time-harmonic near-field analysis. In order to illustrate our theory, we present electromagnetic field simulations of simple as well as more complex nanostructures. Results using the well-known far-field polarization concept are readily reproduced and extended from the point of view of chirality conversion. Y1 - 2016 ER - TY - JOUR A1 - Hammerschmidt, Martin A1 - Barth, Carlo A1 - Pomplun, Jan A1 - Burger, Sven A1 - Becker, Christiane A1 - Schmidt, Frank T1 - Reconstruction of photonic crystal geometries using a reduced basis method for nonlinear outputs JF - Proc. SPIE N2 - Maxwell solvers based on the hp-adaptive finite element method allow for accurate geometrical modeling and high numerical accuracy. These features are indispensable for the optimization of optical properties or reconstruction of parameters through inverse processes. High computational complexity prohibits the evaluation of the solution for many parameters. We present a reduced basis method (RBM) for the time-harmonic electromagnetic scattering problem allowing to compute solutions for a parameter configuration orders of magnitude faster. The RBM allows to evaluate linear and nonlinear outputs of interest like Fourier transform or the enhancement of the electromagnetic field in milliseconds. We apply the RBM to compute light-scattering off two dimensional photonic crystal structures made of silicon and reconstruct geometrical parameters. Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-58187 VL - 9756 SP - 97561R ER - TY - JOUR A1 - Hammerschmidt, Martin A1 - Herrmann, Sven A1 - Pomplun, Jan A1 - Burger, Sven A1 - Schmidt, Frank T1 - Model order reduction for the time-harmonic Maxwell equation applied to complex nanostructures JF - Proc. SPIE N2 - Fields such as optical metrology and computational lithography require fast and efficient methods for solving the time-harmonic Maxwell's equation. Highly accurate geometrical modelling and numerical accuracy at low computational costs are a prerequisite for any simulation study of complex nano-structured photonic devices. We present a reduced basis method (RBM) for the time-harmonic electromagnetic scattering problem based on the hp-adaptive finite element solver JCMsuite capable of handling geometric and non-geometric parameter dependencies allowing for online evaluations in milliseconds. We apply the RBM to compute light-scattering at optical wavelengths of periodic arrays of fin field-effect transistors (FinFETs) where geometrical properties such as the width and height of the fin and gate can vary in a large range. Y1 - 2016 U6 - https://doi.org/10.1117/12.2212367 VL - 9742 SP - 97420M ER - TY - JOUR A1 - Hammerschmidt, Martin A1 - Herrmann, Sven A1 - Pomplun, Jan A1 - Burger, Sven A1 - Schmidt, Frank T1 - Reduced basis method for electromagnetic scattering problem: a case study for FinFETs JF - Optical and Quantum Electronics N2 - Optical 3D simulations in many-query and real-time contexts require new solution strategies. We study an adaptive, error controlled reduced basis method for solving parametrized time-harmonic optical scattering problems. Application fields are, among others, design and optimization problems of nano-optical devices as well as inverse problems for parameter reconstructions occurring e. g. in optical metrology. The reduced basis method pre- sented here relies on a finite element modeling of the scattering problem with parametrization of materials, geometries and sources. Y1 - 2016 U6 - https://doi.org/10.1007/s11082-016-0530-1 VL - 48 SP - 250 ER - TY - JOUR A1 - Jäger, Klaus A1 - Barth, Carlo A1 - Hammerschmidt, Martin A1 - Herrmann, Sven A1 - Burger, Sven A1 - Schmidt, Frank A1 - Becker, Christiane T1 - Simulations of sinusoidal nanotextures for coupling light into c-Si thin-film solar cells JF - Opt. Express Y1 - 2016 U6 - https://doi.org/10.1364/OE.24.00A569 VL - 24 SP - A569 ER - TY - THES A1 - Hammerschmidt, Martin T1 - Optical simulation of complex nanostructured solar cells with a reduced basis method N2 - Simulations of optical processes and complex nanostructured devices have become omnipresent in recent years in several fields of current research and industrial applications, not limited to the field of photovoltaics. Devices or processes are optimized with respect to a certain objective where the underlying physical processes are described by partial differential equations. In photovoltaics and photonics electromagnetic fields are investigated which are governed by Maxwell’s equations. In this thesis a reduced basis method for the solution of the parameter dependent electromagnetic scattering problem with arbitrary parameters is developed. The method is developed with the specific challenges arising in optical simulations of thin-film silicon solar cells in mind. These are large in domain size and have a complex three-dimensional structure, making optimization tasks infeasible if high-accuracy of the electromagnetic field solution is required. The application of the empirical interpolation methods allows to expand an arbitrary parameter dependence affinely. Thus not only geometries, but also material tensors and source fields can be parameterized. Additionally, the required non-linear post-processing steps of the electromagnetic field to derive energy fluxes or volume absorption are addressed. The reduced basis method allows to reduce the computational costs by orders of magnitude compared to efficient finite element solvers. In addition, an efficient tailored domain decomposition algorithm is presented to model incoherent layers or illuminations in optical systems efficiently. This is of particular interest for solar cells in superstrate configuration where the absorber is illuminated through a glass substrate. The developed methods are employed in application examples taken from collaborations with experimentalists active in the joint lab “BerOSE” (Berlin Joint Lab for Optical Simulations for Energy Research). The optical model of a thin-film silicon multi-junction with incoherent light-trapping is characterized in great detail. The computational gains through hybrid, hp adaptive finite elements are studied and the incoherent domain decomposition algorithm is applied to model a more realistic light-trapping by the glass substrate. The numerical examples of a hexagonal nano-hole array and multi-junction silicon solar cell with a tunable intermediate reflector layer show that the reduced basis method is well suited as a forward solver for modeling and optimization tasks arising in photovoltaics and photonics. Reduced models for illumination and geometric parameters are built providing up to five orders of magnitude savings in computational costs. Resonance phenomena present in the nano-hole array example are detected and the model adapts itself automatically. KW - reduced basis method; model reduction; electromagnetics; photonics; solar cells; nanooptics; Maxwells equations; incoherence Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:188-fudissthesis000000102429-1 UR - http://www.diss.fu-berlin.de/diss/receive/FUDISS_thesis_000000102429 ER - TY - CHAP A1 - Jäger, Klaus A1 - Hammerschmidt, Martin A1 - Köppel, Grit A1 - Burger, Sven A1 - Becker, Christiane T1 - On Accurate Simulations of Thin-Film Solar Cells With a Thick Glass Superstrate T2 - Light, Energy and the Environment 2016 Y1 - 2016 U6 - https://doi.org/10.1364/PV.2016.PM3B.5 SP - PM3B.5 ER - TY - CHAP A1 - Mangalgiri, Gauri A1 - Šiškins, Makars A1 - Arslanova, Alina A1 - Hammerschmidt, Martin A1 - Manley, Phillip A1 - Riedel, Wiebke A1 - Schmid, Martina T1 - Highly Transmittive Broadband Dielectric Nanoholes T2 - CLEO Y1 - 2017 U6 - https://doi.org/10.1364/CLEO_AT.2017.JTu5A.117 SP - JTu5A.117 ER - TY - CHAP A1 - Jäger, Klaus A1 - Köppel, Grit A1 - Hammerschmidt, Martin A1 - Burger, Sven A1 - Becker, Christiane T1 - Accurate optical simulations of periodic nanostructures on a thick glass substrate T2 - 29th Workshop on Quantum Solar Energy Conversion - (QUANTSOL) Y1 - 2017 ER - TY - GEN A1 - Hammerschmidt, Martin A1 - Döpking, Sandra A1 - Burger, Sven A1 - Matera, Sebastian T1 - Field Heterogeneities and their Impact on Photocatalysis: Combining optical and kinetic Monte Carlo Simulations on the Nanoscale N2 - Gaining insights into the working principles of photocatalysts on an atomic scale is a challenging task. The obviously high complexity of the reaction mechanism involving photo-excited electrons and holes is one reason. Another complicating aspect is that the electromagnetic field, driving photocatalysis, is not homogeneous on a nanoscale level for particle based catalysts as it is influenced by the particle’s shape and size. We present a simple model, inspired by the CO2 reduction on titania anatase, which addresses the impact of these heterogeneities on the photocatalytic kinetics by combining kinetic Monte Carlo with electromagnetic wave simulations. We find that average activity and especially efficiency might differ significantly between different particles. Moreover, we find sizable variation of the catalytic activity on a single facet of a nanocrystal. Besides this quantitative heterogeneity, the coverage situation in general changes laterally on this facet and we observe a concomitant change of the rate-determining steps. This heterogeneity on all levels of photocatalytic activity is masked in experimental studies, where only the spatially averaged activity can be addressed. Microkinetic models based on experimental findings might therefore not represent the true micro- scopic behavior, and mechanistic conclusion drawn from these need to be handled with care. T3 - ZIB-Report - 17-20 Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-63690 SN - 1438-0064 ER - TY - GEN A1 - Hammerschmidt, Martin A1 - Pomplun, Jan A1 - Burger, Sven A1 - Schmidt, Frank T1 - Adaptive sampling strategies for efficient parameter scans in nano-photonic device simulations N2 - Rigorous optical simulations are an important tool in optimizing scattering properties of nano-photonic devices and are used, for example, in solar cell optimization. The finite element method (FEM) yields rigorous, time-harmonic, high accuracy solutions of the full 3D vectorial Maxwell's equations [1] and furthermore allows for great flexibility and accuracy in the geometrical modeling of these often complex shaped 3D nano-structures. A major drawback of frequency domain methods is the limitation of single frequency evaluations. For example the accurate computation of the short circuit current density of an amorphous silicon / micro-crystalline multi-junction thin film solar cell may require the solution of Maxwell's equations for over a hundred different wavelengths if an equidistant sampling strategy is employed. Also in optical metrology, wavelength scans are frequently used to reconstruct unknown geometrical and material properties of optical systems numerically from measured scatterometric data. In our contribution we present several adaptive numerical integration and sampling routines and study their efficiency in the context of the determination of generation rate profiles of solar cells. We show that these strategies lead to a reduction in the computational effort without loss of accuracy. We discuss the employment of tangential information in a Hermite interpolation scheme to achieve similar accuracy on coarser grids. We explore the usability of these strategies for scatterometry and solar cell simulations. T3 - ZIB-Report - 14-20 KW - finite element method KW - optical simulations KW - adaptive sampling KW - optical metrology KW - parameter scans KW - solar cells Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-50395 SN - 1438-0064 ER - TY - GEN A1 - Hammerschmidt, Martin A1 - Lockau, Daniel A1 - Zschiedrich, Lin A1 - Schmidt, Frank T1 - Optical modelling of incoherent substrate light-trapping in silicon thin film multi-junction solar cells with finite elements and domain decomposition N2 - In many experimentally realized applications, e.g. photonic crystals, solar cells and light-emitting diodes, nano-photonic systems are coupled to a thick substrate layer, which in certain cases has to be included as a part of the optical system. The finite element method (FEM) yields rigorous, high accuracy solutions of full 3D vectorial Maxwell's equations [1] and allows for great flexibility and accuracy in the geometrical modelling. Time-harmonic FEM solvers have been combined with Fourier methods in domain decomposition algorithms to compute coherent solutions of these coupled system. [2,3] The basic idea of a domain decomposition approach lies in a decomposition of the domain into smaller subdomains, separate calculations of the solutions and coupling of these solutions on adjacent subdomains. In experiments light sources are often not perfectly monochromatic and hence a comparision to simulation results might only be justified if the simulation results, which include interference patterns in the substrate, are spectrally averaged. In this contribution we present a scattering matrix domain decomposition algorithm for Maxwell's equations based on FEM. We study its convergence and advantages in the context of optical simulations of silicon thin film multi-junction solar cells. This allows for substrate light-trapping to be included in optical simulations and leads to a more realistic estimation of light path enhancement factors in thin-film devices near the band edge. T3 - ZIB-Report - 14-21 KW - finite element method KW - rigorous optical modeling KW - domain decomposition KW - multi-junction solar cells KW - thin-film silicon solar cells KW - incoherent layers KW - incoherent light-trapping Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-50410 SN - 1438-0064 ER -