Ulrike Grossner

Last Name

Grossner

First Name

Ulrike

ORCID

0000-0002-2495-8550

Organisational unit

09480 - Grossner, Ulrike / Grossner, Ulrike

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Publications 1 - 10 of 138

S-PEEC-DI: Surface Partial Element Equivalent Circuit method with decoupling integrals
De Lauretis, Maria; Haller, Elena; Romano, Daniele; et al. (2025)
Engineering Analysis with Boundary Elements
In computational electromagnetics, numerical methods are generally optimized for triangular or tetrahedral meshes. However, typical objects of general interest in electronics, such as diode packages or antennas, have a Manhattan-type geometry that can be modeled with orthogonal and rectangular meshes. The advantage of orthogonal meshes is that they allow analytic solutions of the integral equations. In this work, we optimize the decoupling of the integrals used in the Surface formulation of the Partial Element Equivalent Circuit (S-PEEC) method for rectangular meshes. We consider a previously proposed decoupling strategy, and we lighten the underlying math by generalizing it. The new method shows improved accuracy and computational time because the number of decoupling integrals is generally reduced. The new S-PEEC method with decoupling integrals is named S-PEEC-DI. The S-PEEC-DI method is tested on a realistic diode package and compared with the volumetric PEEC (V-PEEC) and two well-known commercial solvers.
Muon Interaction with Negative-U and High-Spin-State Defects: Differentiating between C and Si Vacancies in 4H-SiC
Woerle, Judith; Etzelmüller Bathen, Marianne; Prokscha, Thomas; et al. (2020)
Physical Review Applied
Low-energy muon-spin-rotation spectroscopy (LE-μ SR) is employed to study silicon and carbon vacancies in proton-irradiated 4H-Si C. We show that the implanted muon is quickly attracted to the negative Si vacancy (V Si), where it forms a paramagnetic muonium (Mu0) state, resulting in a reduction of the diamagnetic fraction. In samples with predominantly C vacancies (VC), on the other hand, the formation of Mu0 is very short lived and the muon quickly captures a second electron to form a diamagnetic Mu− state. The results are corroborated by density-functional calculations, where significant differences in the relaxation mechanism of the nearest-neighbor dangling bonds of the vacancies are discussed. We propose that the LE-μ SR technique is capable of differentiating between high-spin and negative-U behavior in semiconducting materials. Finally, our findings emphasize the large potential of LE-μ SR to probe near-surface semiconductor defects, a capability that is crucial for further development of many electronic and quantum technology applications.
Phosphorus implantation into 4H-SiC at room and elevated temperature
Müting, Johanna; Bobal, V.; Vines, Lasse; et al. (2021)
Semiconductor Science and Technology
Phosphorus implantation is essential to create localized n-type doped regions in 4H-SiC. The realized profiles may, however, deviate from the desired ones, affecting device properties. In order to characterize typical process parameters and to enable correct prediction of the desired structures, phosphorous implantation into 4H-SiC with a variety of doses and energies is performed at room and elevated temperature. Exemplary post-implantation annealing shows no significant influence on the phosphorus distribution. The as-implanted profiles, analyzed by secondary ion mass spectrometry, show a clear dependence on implantation dose and temperature. High sample temperature at implantation suppresses channeling in case of low and medium doses due to increased lattice vibrations, while crystal damage is restored in case of high doses leading to increased opportunities for channeling, pointing toward different crystal damage and energy loss mechanisms. Finally, the Monte Carlo profiles of the simulation tools stopping and range of ions in matter (SRIM) and Sentaurus Process are critically compared with the experimental profiles.
Accurate Calculation of Partial Inductances for the Orthogonal PEEC Formulation
Kovacevic-Badstuebner, Ivana; Romano, Daniele; Lombardi, Luigi; et al. (2021)
IEEE Transactions on Electromagnetic Compatibility
The Partial Element Equivalent Circuit (PEEC) method is promising numerical technique for three-dimension electromagnetic modeling across various application fields. In the framework of the PEEC method, the partial elements modeling the magnetic and electric field coupling between elementary volumes and surfaces are computed by double-folded volume and surface integrals. Assuming the quasi-static hypothesis and an orthogonal mesh, the integrals have been computed by the analytical formulas derived in literature, which significantly reduces the computational time in comparison to the numerical integration. However, the existing analytical formulas are affected by significant numerical errors for certain PEEC structural mesh necessary to model the skin and proximity effects with a higher accuracy. To utilize the full potential of the PEEC method, the calculation of partial elements has to be carefully addressed, which has not been investigated in a comprehensive way so far. Accordingly, this paper presents a systematic accuracy analysis of the existing closed-form analytical formulas and methods for calculating the self and mutual inductances between two rectangular conductors. Additionally, a new strategy to select a proper analytical formula depending on the dimensions and positions of two conductors is proposed, which allows the mutual inductance extraction with a relative error of less than 0.1 % . The new method is systematically validated on examples of 3-D dense PEEC systems using the quadruple precision arithmetic as reference.
Exploring the Relation Between SEEs Caused by Heavy-Ion Irradiation and Defects in SiC Devices
Goncalves de Medeiros, Helton; Martinella, Corinna; Belanche Guadas, Manuel; et al. (2025)
IEEE Transactions on Nuclear Science
Heavy-ion irradiation with different linear energy transfers (LETs) and ion penetration ranges were used to investigate the radiation tolerance of SiC power diodes. Single event leakage current (SELC) degradation was observed for ion ranges shorter than the epitaxial layer thickness. To elucidate the root cause of the observed radiation effects, deep-level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS) were performed. Both, the ratio between the boron peak contributions and their capture cross-section as measured directly, exhibit a change in value after heavy-ion irradiation.
Highly Accurate Virtual Dynamic Characterization of Discrete SiC Power Devices
Kovacevic-Badstuebner, Ivana; Ziemann, Thomas; Kakarla, Bhagyalakshmi; et al. (2017)
Proceedings of the 29th International Symposium on Power Semiconductor Devices and ICs, ISPSD 2017
SiC Device Manufacturing: How Processing Impacts the Material and Device Properties
Grossner, Ulrike; Alfieri, Giovanni; Nipoti, Roberta (2015)
Materials Science Forum
Extended Analysis of Power Cycling Behavior of TOPackaged SiC Power MOSFETs
Kovacevic-Badstuebner, Ivana; Race, Salvatore; Grossner, Ulrike; et al. (2023)
2023 IEEE International Reliability Physics Symposium (IRPS)
This paper presents an extended analysis of TOpackaged SiC power MOSFETs after power cycling (PC) tests. Namely, it is shown that initially present voids in soft lead-based solder die attach disappear not only after certain number of active PC tests, but also after thermal shock tests. Hereby, the conclusion that solder die attach is not the weak spot of SiC power MOSFET packages with an epoxy mold compound (EMC) encapsulation is further supported. Furthermore, an electro-thermo-mechanical (ETM) model developed in-house is used to correlate the dominant wear-out failure of bond wires to the PC test parameters such as heating current, temperature amplitude, and heating on-time, as well as to the thickness of top source die metallization.
Full-Wave Computation of the Electric Field in the Partial Element Equivalent Circuit Method Using Taylor Series Expansion of the Retarded Green's Function
Kovacevic-Badstuebner, Ivana; Romano, Daniele; Antonini, Giulio; et al. (2020)
IEEE Transactions on Microwave Theory and Techniques
This article presents new analytical formulas for the efficient computation of the full-wave electric field generated by conductive, dielectric, and magnetic media in the framework of the partial element equivalent circuit (PEEC) method. To this aim, the full-wave Green's function is handled by the Taylor series expansion leading to three types of integrals for which new analytical formulas are provided in order to avoid slower numerical integration. An orthogonal (Manhattan type) tessellation of the geometries is assumed, and the electrical quantities, i.e., currents, charges, and magnetization, are expanded in space through rectangular basis functions. The full-wave electric field radiated by charges, currents, and magnetization is computed analytically in the postprocessing step. The proposed closed-form computation of the electric field is tested using two examples, comparing the results obtained by the derived analytical formulas with the results from a finite element method solver. © 1963-2012 IEEE
Towards Digital Twins for the Optimization of Power Electronic Switching Cells with Discrete SiC Power MOSFETs
Race, Salvatore; Nagel, Michel; Kovacevic-Badstuebner, Ivana; et al. (2022)
PCIM Europe 2022: International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management Proceedings
Layout optimization of power electronic switching cells is highly important for the design of high-efficiency fast-switching power converters. The aim of this paper is to identify PCB layout design parameters leading to an improved layout design with respect to low switching losses and low electromagnetic interference. A digital twin of the switching cells containing discrete silicon carbide power devices was developed and verified by double-pulse measurements. The results identify and quantify the non-negligible influence of the layout parasitic capacitances on the optimization of switching losses. The observed modeling challenges point towards the need for more accurate EM modeling techniques for power electronics applications and for standardization of SiC power MOSFET Spice models.

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Ulrike Grossner

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