Researcher, Division Photovoltaics
| since 2021 | Research Fellow at the University of Warwick (UK) |
| since 2017 | Postdoctoral Researcher at Fraunhofer ISE and the University of Freiburg |
| 2012-2017 |
PhD thesis "Lifetime-limiting defects in monocrystalline silicon" at University of Freiburg and Fraunhofer ISE |
| 2012 | Diploma in Materials Science (Engineering) from Technical University Darmstadt (with distinction) |
| 2010 | Intern at Schott Solar (Alzenau) |
| 2008-2009 |
Student research assistant at Fraunhofer LBF |
| 2006-2012 |
Student at Technical University Darmstadt (materials science) |
External publication list on Google Scholar
Publication list from the Fraunhofer-Publica database:
| Jahr Year | Titel/Autor:in Title/Author | Publikationstyp Publication Type |
|---|---|---|
| 2024 | Stability of industrial gallium-doped Czochralski silicon PERC cells and wafers Niewelt, Tim; Maischner, Felix; Kwapil, Wolfram; Khorani, Edris; Pain, Sophie L.; Jung, Yujin; Hopkins, Eduard C. B.; Frosch, Manfred; Altermatt, Pietro P.; Guo, Harry; Wang, Yuchin; Grant, Nicholas E.; Murphy, John D. |
Zeitschriftenaufsatz Journal Article |
| 2023 | LeTID Stability Tests on Gallium-Doped Industrial PERC Cells and Wafers Niewelt, Tim; Maischner, Felix; Khorani, Edris; Pain, Sophie; Grant, Nicholas E.; Kwapil, Wolfram; Altermatt, Pietro P.; Murphy, John D. |
Vortrag Presentation |
| 2023 | On the Conversion Between Recombination Rates and Electronic Defect Parameters in Semiconductors Juhl, Mattias K.; Heinz, Friedemann; Coletti, Gianluca; Rougieux, Fiacre; Sun, Chang; Vacqueiro Contreras, Michelle; Niewelt, Tim; Krich, Jacob; Schubert, Martin |
Zeitschriftenaufsatz Journal Article |
| 2023 | Mechanisms of Silicon Surface Passivation by Negatively Charged Hafnium Oxide Thin Films Wratten, Ailish; Pain, Sophie L.; Walker, David; Renz, Arne B.; Khorani, Edris; Niewelt, Tim; Grant, Nicholas E.; Murphy, John D. |
Zeitschriftenaufsatz Journal Article |
| 2023 | Electronic Band Offset Determination of Oxides Grown by Atomic Layer Deposition on Silicon Khorani, Edris; Meßmer, Christoph Alexander; Pain, Sophie L.; Niewelt, Tim; Healy, Brendan; Ailish, Wratten; Walker, Marc; Grant, Nicholas E.; Murphy, John D. |
Zeitschriftenaufsatz Journal Article |
| 2023 | Silicon-based passivating contacts: The TOPCon route Glunz, Stefan; Steinhauser, Bernd; Polzin, Jana-Isabelle; Luderer, Christoph; Grübel, Benjamin; Niewelt, Tim; Okasha, Asmaa; Bories, Mathias; Nagel, Henning; Krieg, Katrin; Feldmann, Frank; Richter, Armin; Bivour, Martin; Hermle, Martin |
Zeitschriftenaufsatz Journal Article |
| 2023 | Stable chemical enhancement of passivating nanolayer structures grown by atomic layer deposition on silicon Pain, Sophie L.; Khorani, Edris; Niewelt, Tim; Wratten, Ailish; Walker, Marc; Grant, Nicholas E.; Murphy, John D. |
Zeitschriftenaufsatz Journal Article |
| 2023 | The Impact of Different Hydrogen Configurations on Light- and Elevated-Temperature-Induced Degradation Hammann, Benjamin; Assmann, Nicole; Weiser, Philip M.; Kwapil, Wolfram; Niewelt, Tim; Schindler, Florian; Søndenå, Rune; Monakhov, Eduard V.; Schubert, Martin |
Zeitschriftenaufsatz Journal Article |
| 2023 | Exploring hafnium oxide’s potential for passivating contacts for silicon solar cells Wratten, Ailish; Pain, Sophie L.; Yadav, Anup; Khorani, Edris; Niewelt, Tim; Black, Lachlan; Bartholazzi, Gabriel; Walker, David; Grant, Nicholas E.; Murphy, John D. |
Zeitschriftenaufsatz Journal Article |
| 2023 | Quantifying Surface Recombination - Improvements in Determination and Simulation of the Surface Recombination Parameter J0s Hammann, Benjamin; Steinhauser, Bernd; Fell, Andreas; Post, Regina; Niewelt, Tim; Kwapil, Wolfram; Wolf, Andreas; Richter, Armin; Höffler, Hannes; Schubert, Martin |
Zeitschriftenaufsatz Journal Article |
| 2023 | Epitaxially Grown p-type Silicon Wafers Ready for Cell Efficiencies Exceeding 25% Rittmann, Clara; Schindler, Florian; Richter, Armin; Niewelt, Tim; Stolzenburg, Hannah; Steinhauser, Bernd; Dalke, Jonas; Drießen, Marion; Weiss, Charlotte; Janz, Stefan; Schubert, Martin |
Zeitschriftenaufsatz Journal Article |
| 2022 | Establishing the True Limit of Silicon’s Performance: A Multi-Institutional Collaboration to Redefine Silicon’s Carrier Lifetime Limit Niewelt, Tim |
Vortrag Presentation |
| 2022 | Epitaxially grown p-type silicon wafers ready for cell efficiencies exceeding 25 % Rittmann, Clara; Dalke, Jonas; Richter, Armin; Steinhauser, Bernd; Drießen, Marion; Weiss, Charlotte; Schindler, Florian; Schubert, Martin; Janz, Stefan; Niewelt, Tim; Stolzenburg, Hannah |
Vortrag Presentation |
| 2022 | Carrier lifetimes in high-lifetime silicon wafers and solar cells measured by photoexcited muon spin spectroscopy Murphy, John D.; Grant, Nicholas E.; Pain, Sophie L.; Niewelt, Tim; Wratten, Ailish; Khorani, Edris; Markevich, Vladimir P.; Peaker, Anthony R.; Altermatt, Pietro P.; Lord, James S.; Yokoyama, Koji |
Zeitschriftenaufsatz Journal Article |
| 2022 | Reassessment of the intrinsic bulk recombination in crystalline silicon Niewelt, Tim; Steinhauser, Bernd; Richter, Armin; Veith-Wolf, B.; Fell, Andreas; Hammann, Benjamin; Grant, N.E.; Black, L.; Tan, J.; Youssef, A.; Murphy, J.D.; Schmidt, J.; Schubert, Martin C.; Glunz, Stefan W. |
Zeitschriftenaufsatz Journal Article |
| 2022 | Engineering the carrier lifetime and switching speed in Si-based mm-wave photomodulators Hooper, Ian R.; Khorani, Edris; Romain, Xavier; Barr, Lauren E.; Niewelt, Tim; Saxena, Sonal; Wratten, Ailish; Grant, Nicholas E.; Murphy, John D.; Hendry, Euan |
Zeitschriftenaufsatz Journal Article |
| 2022 | High Minority Charge Carrier Lifetimes in Crystalline Silicon - Auger, Radiative and Surface Recombination Niewelt, Tim |
Vortrag Presentation |
| 2022 | Electronic Characteristics of Ultra-Thin Passivation Layers for Silicon Photovoltaics Pain, Sophie L.; Khorani, Edris; Niewelt, Tim; Wratten, Ailish; Paez Fajardo, Galo J.; Winfield, Ben P.; Bonilla, Ruy S.; Walker, Marc; Piper, Louis F. J.; Grant, Nicholas E.; Murphy, John D. |
Zeitschriftenaufsatz Journal Article |
| 2022 | Carrier Lifetime Limitation of Industrial Ga-Doped Cz-Grown Silicon after Different Solar Cell Process Flows Post, Regina; Niewelt, Tim; Kwapil, Wolfram; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2021 | Mitigation of LID and LeTID in photovoltaics - facets of hydrogen introduction Niewelt, Tim; Kwapil, Wolfram; Hammann, Benjamin; Schön, Jonas; Schindler, Florian; Schubert, Martin C. |
Vortrag Presentation |
| 2021 | Radiative recombination in silicon photovoltaics: Modeling the influence of charge carrier densities and photon recycling Fell, Andreas; Niewelt, Tim; Steinhauser, Bernd; Heinz, Friedemann D.; Schubert, Martin C.; Glunz, Stefan W. |
Zeitschriftenaufsatz Journal Article |
| 2021 | Temperature Gradient Image Analysis to optimize an Ultrafast Regeneration of boron-oxygen-related defects Roder, Sebastian; Niewelt, Tim; Brand, Andreas A.; Schneider, Jale; Nekarda, Jan |
Zeitschriftenaufsatz Journal Article |
| 2021 | Thermal Activation of Hydrogen for Defect Passivation in poly-Si Based Passivating Contacts Polzin, Jana-Isabelle; Hammann, Benjamin; Niewelt, Tim; Kwapil, Wolfram; Hermle, Martin; Feldmann, Frank |
Zeitschriftenaufsatz Journal Article |
| 2021 | The radiative recombination coefficient of silicon: Reassesment of its charge carrier density dependence Fell, Andreas; Niewelt, Tim; Steinhauser, Bernd; Heinz, Friedemann D.; Schubert, Martin C.; Glunz, Stefan W. |
Konferenzbeitrag Conference Paper |
| 2021 | Extraordinarily High Minority Charge Carrier Lifetime Observed in Crystalline Silicon Steinhauser, Bernd; Niewelt, Tim; Richter, Armin; Eberle, Rebekka; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2021 | Gallium-Doped Silicon for High-Efficiency Commercial Passivated Emitter and Rear Solar Cells Grant, N.E.; Altermatt, Pietro P.; Niewelt, Tim; Post, Regina; Kwapil, Wolfram; Schubert, Martin C.; Murphy, J.D. |
Zeitschriftenaufsatz Journal Article |
| 2021 | Experimental and Theoretical Study of Oxygen Precipitation and the Resulting Limitation of Silicon Solar Cell Wafers Schön, Jonas; Niewelt, Tim; Mu, D.; Maus, Stephan; Wolf, Andreas; Murphy, J.D.; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2021 | Influence of Dopant Elements on Degradation Phenomena in B- and Ga-Doped Czochralski-grown Silicon Kwapil, Wolfram; Dalke, Jonas; Post, Regina; Niewelt, Tim |
Zeitschriftenaufsatz Journal Article |
| 2020 | Assessment of Influencing Factors on Lifetime-Based Defect Analysis Post, Regina; Niewelt, Tim; Kwapil, Wolfram; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2020 | Temporary Recovery of the Defect Responsible for Light- and Elevated Temperature-Induced Degradation: Insights into the Physical Mechanisms behind LeTID Kwapil, Wolfram; Schön, Jonas; Niewelt, Tim; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2020 | LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals Kwapil, Wolfram; Dalke, Jonas; Niewelt, Tim; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2020 | Impact of Postplating Annealing on Defect Activation in Boron-Doped PERC Solar Cells Grübel, Benjamin; Theil, G.C.; Roder, Sebastian; Niewelt, Tim; Kluska, Sven |
Zeitschriftenaufsatz Journal Article |
| 2020 | Electron and proton irradiation effect on the minority carrier lifetime in SiC passivated p-doped Ge wafers for space photovoltaics Weiss, Charlotte; Park, Seonyong; Lefèvre, Jérémie; Boizot, Bruno; Mohr, Christian; Cavani, Olivier; Picard, Sandrine; Kurstjens, Rufi; Niewelt, Tim; Janz, Stefan |
Zeitschriftenaufsatz Journal Article |
| 2020 | Investigation of Two-level Defects in Injection Dependent Lifetime Spectroscopy Zhu, Y.; Sun, C.; Niewelt, Tim; Coletti, Gianluca; Hameiri, Z. |
Zeitschriftenaufsatz Journal Article |
| 2019 | Imaging Interstitial Iron Concentrations in Gallium-Doped Silicon Wafers Post, Regina; Niewelt, Tim; Schön, Jonas; Schindler, Florian; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2019 | Impact of POCl3 Diffusion Process Parameters on Oxygen Precipitation in Czochralski-Grown Silicon Maus, Stephan; Lohmüller, Sabrina; Mu, D.; Schön, Jonas; Niewelt, Tim; Wolf, Andreas; Preu, Ralf |
Konferenzbeitrag Conference Paper |
| 2019 | Re-evaluation of the SRH-Parameters for the FeGa Defect Post, Regina; Niewelt, Tim; Yang, W.; MacDonald, Daniel; Kwapil, Wolfram; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2019 | Analysis of Temperature Dependent Characteristics of Diffused Regions in Silicon Solar Cells Eberle, Rebekka; Fell, Andreas; Richter, Armin; Niewelt, Tim; Schindler, Florian; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2019 | Analysis of Temperature Dependent Surface Recombination Properties Eberle, Rebekka; Fell, Andreas; Niewelt, Tim; Schindler, Florian; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2019 | Lifetime-limiting defects in monocrystalline Silicon Niewelt, Tim |
Dissertation Doctoral Thesis |
| 2019 | Investigation of LeTID where we can Control it - Application of FZ Silicon for Defect Studies Niewelt, Tim; Post, Regina; Schindler, Florian; Kwapil, Wolfram; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2018 | Analysis of Defect Recombination Based on Shockley-Read-Hall Statistics - Where we com from: The DPSS Approach Niewelt, Tim |
Vortrag Presentation |
| 2018 | Taking Monocrystalline Silicon to the Ultimate Lifetime Limit Niewelt, Tim; Richter, Armin; Kho, T.; Grant, N.; Bonilla, Ruy S.; Steinhauser, Bernd; Polzin, Jana-Isabelle; Feldmann, Frank; Hermle, Martin; Murphy, J.; Phang, S.; Kwapil, Wolfram; Schubert, Martin C. |
Vortrag Presentation |
| 2018 | Carrier-Selective Contacts for High-Efficiency Silicon Solar Cells Glunz, Stefan W.; Feldmann, Frank; Polzin, Jana-Isabelle; Steinhauser, Bernd; Müller, Ralph; Fell, Andreas; Richter, Armin; Niewelt, Tim; Schindler, Florian; Kökbudak, G.; Turan, R.; Nogay, G.; Löper, Philipp; Young, D.L.; Lee, Benjamin G.; Stradins, P.; Bivour, Martin; Cariou, Romain; Benick, Jan; Dimroth, Frank; Hermle, Martin |
Vortrag Presentation |
| 2018 | Iron Imaging on Ga Doped Wafers Post, Regina; Niewelt, Tim; Schön, Jonas; Schindler, Florian; Schubert, Martin C. |
Vortrag Presentation |
| 2018 | An open source based repository for defects in silicon Juhl, Mattias K.; Heinz, Friedemann D.; Coletti, Gianluca; MacDonald, Daniel; Rougieux, Fiacre E.; Schindler, Florian; Niewelt, Tim; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2018 | Taking monocrystalline silicon to the ultimate lifetime limit Niewelt, Tim; Richter, Armin; Kho, T.C.; Grant, N.E.; Bonilla, Ruy S.; Steinhauser, Bernd; Polzin, Jana-Isabelle; Feldmann, Frank; Hermle, Martin; Murphy, J.D.; Phang, S.P.; Kwapil, Wolfram; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2018 | Limiting Effects in Crystalline Silicon for High-Efficiency Solar Cells Niewelt, Tim; Richter, Armin; Eberle, Rebekka; Post, Regina; Schön, Jonas; Schindler, Florian; Hermle, Martin; Kwapil, Wolfram; Schubert, Martin C. |
Vortrag Presentation |
| 2017 | Long-term stability of aluminum oxide based surface passivation schemes under illumination at elevated temperatures Niewelt, Tim; Kwapil, Wolfram; Selinger, M.; Richter, Armin; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2017 | Understanding the light-induced degradation at elevated temperatures: Similarities between multicrystalline and floatzone p-type silicon Niewelt, Tim; Schindler, Florian; Kwapil, Wolfram; Eberle, Rebekka; Schön, Jonas; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2017 | Kinetics of carrier-induced degradation at elevated temperature in multicrystalline silicon solar cells Kwapil, Wolfram; Niewelt, Tim; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2017 | Experimental evidence of electron capture and emission from trap levels in Cz silicon Heinz, Friedemann D.; Niewelt, Tim; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2017 | Superacid-treated silicon surfaces: Extending the limit of carrier lifetime for photovoltaic applications Grant, N.E.; Niewelt, Tim; Wilson, N.R.; Wheeler-Jones, E.C.; Bullock, J.; Al-Amin, M.; Schubert, Martin C.; Veen, A.C. van; Javey, A.; Murphy, J.D. |
Zeitschriftenaufsatz Journal Article |
| 2017 | Degradation of Crystalline Silicon Due to Boron Oxygen Defects Niewelt, Tim; Schön, Jonas; Warta, Wilhelm; Glunz, Stefan W.; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2017 | Stability of effective lifetime of float-zone silicon wafers with AlOx surface passivation schemes under illumination at elevated temperature Niewelt, Tim; Kwapil, Wolfram; Selinger, M.; Richter, Armin; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2017 | Light-induced activation and deactivation of bulk defects in boron-doped float-zone silicon Niewelt, Tim; Selinger, M.; Grant, N.; Kwapil, Wolfram; Murphy, J.D.; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2016 | Experimental proof of the slow light-induced degradation component in compensated n-type silicon Niewelt, Tim; Schön, Jonas; Broisch, Juliane; Rein, Stefan; Haunschild, Jonas; Warta, Wilhelm; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2016 | Identification of lifetime limiting defects by temperature- and injection-dependent photoluminescence imaging Schön, Jonas; Youssef, A.; Park, S.; Mundt, Laura E.; Niewelt, Tim; Mack, Sebastian; Nakajima, K.; Morishita, K.; Murai, R.; Jensen, M.A.; Buonassisi, Toni; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2016 | Fast in-situ photoluminescence analysis for a recombination parameterization of the fast BO defect component in silicon Niewelt, Tim; Mägdefessel, Sven; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2016 | A unified parameterization of the formation of boron oxygen defects and their electrical activity Niewelt, Tim; Schön, Jonas; Broisch, Juliane; Mägdefessel, Sven; Warta, Wilhelm; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2016 | Swirl Defect Investigation Using Temperature- and Injection-Dependent Photoluminescence Imaging Youssef, A.; Schön, Jonas; Niewelt, Tim; Mack, Sebastian; Park, Seonyong; Nakajima, K.; Morishita, K.; Murai, R.; Jensen, M.A.; Buonassisi, Toni; Schubert, Martin C. |
Konferenzbeitrag Conference Paper |
| 2015 | Spatially resolved impurity identification via temperature- and injection-dependent photoluminescence imaging Mundt, Laura E.; Schubert, Martin C.; Schön, Jonas; Michl, Bernhard; Niewelt, Tim; Schindler, Florian; Warta, Wilhelm |
Zeitschriftenaufsatz Journal Article |
| 2015 | Electrical characterization of the slow boron oxygen defect component in Czochralski silicon Niewelt, Tim; Schön, Jonas; Broisch, Juliane; Warta, Wilhelm; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2015 | Characterization and modelling of the boron-oxygen defect activation in compensated n-type silicon Schön, Jonas; Niewelt, Tim; Broisch, Juliane; Warta, Wilhelm; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2015 | Light-Induced Degradation and Regeneration in n-Type Silicon Niewelt, Tim; Broisch, Juliane; Schön, Jonas; Haunschild, Jonas; Rein, Stefan; Warta, Wilhelm; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2014 | Interstitial oxygen imaging from thermal donor growth - a fast photoluminescence based method Niewelt, Tim; Lim, S.; Holtkamp, J.; Schön, Jonas; Warta, Wilhelm; MacDonald, Daniel; Schubert, Martin C. |
Zeitschriftenaufsatz Journal Article |
| 2012 | Passivation layers for indoor solar cells at low irradiation intensities Rühle, Karola; Rauer, Michael; Rüdiger, Marc; Giesecke, Johannes A; Niewelt, Tim; Schmiga, Christian; Glunz, Stefan W.; Kasemann, Martin |
Zeitschriftenaufsatz Journal Article |
| 2012 | Broad Range Injection-Dependent Minority Carrier Lifetime from Photoluminescence Giesecke, Johannes A; Niewelt, Tim; Rüdiger, Marc; Rauer, Michael; Schubert, Martin C.; Warta, Wilhelm |
Zeitschriftenaufsatz Journal Article |
Fraunhofer Institute for Solar Energy Systems ISE