Veröffentlichungen
2020 |
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M. Winter, S. Bordihn, R. Peibst, R. Brendel, and J. Schmidt IEEE Journal of Photovoltaics 10 (2), 423-430, (2020), ISSN: 2156-3403. Abstract | Links | BibTeX | Schlagwörter: Carrier lifetime, Degradation, Poly-Si, Poly-Si on oxide (POLO), silicon, surface passivation @article{Winter2020,
title = {Degradation and Regeneration of n+-Doped Poly-Si Surface Passivation on p-Type and n-Type Cz-Si Under Illumination and Dark Annealing}, author = {M Winter and S Bordihn and R Peibst and R Brendel and J Schmidt}, doi = {10.1109/JPHOTOV.2020.2964987}, issn = {2156-3403}, year = {2020}, date = {2020-03-01}, journal = {IEEE Journal of Photovoltaics}, volume = {10}, number = {2}, pages = {423-430}, abstract = {Degradation and regeneration of recombination parameters can occur in the bulk and at the surfaces of silicon solar cells. This article focuses on the time-resolved analysis of the recombination properties of textured 1.7 Ω cm boron-doped p-type Cz-Si and 5 Ω cm phosphorus-doped n-type Cz-Si wafers, where the surfaces are passivated by n+ poly-Si on interfacial oxide layers exposed to a rapid thermal annealing (RTA) step in a conventional firing furnace. We observe a thermally activated instability in the lifetime over the entire examined injection range. Our experiments show that minority carrier injection (e.g., by illumination) is not required. Degradation in the surface passivation quality of the poly-Si on oxide layer—corresponding to an increase of the saturation current density J0 by up to a factor of five—causes the degradation of the effective lifetime. Interestingly, the surface passivation fully regenerates under prolonged annealing and finally improves even beyond the initial state. Both the extent of the lifetime degradation and the change in J0 depend on the postprocessing treatment temperature which we varied between 80 and 400 °C. Our results indicate that two different processes are responsible for the degradation and the regeneration. Reference samples which did not receive an RTA treatment show no degradation of the surface passivation quality. The RTA treatment applied therefore triggers the degradation effect. A large improvement of the surface passivation quality under prolonged annealing (e.g., at 400 °C) is observed for all samples examined in this study.}, keywords = {Carrier lifetime, Degradation, Poly-Si, Poly-Si on oxide (POLO), silicon, surface passivation}, pubstate = {published}, tppubtype = {article} } Degradation and regeneration of recombination parameters can occur in the bulk and at the surfaces of silicon solar cells. This article focuses on the time-resolved analysis of the recombination properties of textured 1.7 Ω cm boron-doped p-type Cz-Si and 5 Ω cm phosphorus-doped n-type Cz-Si wafers, where the surfaces are passivated by n+ poly-Si on interfacial oxide layers exposed to a rapid thermal annealing (RTA) step in a conventional firing furnace. We observe a thermally activated instability in the lifetime over the entire examined injection range. Our experiments show that minority carrier injection (e.g., by illumination) is not required. Degradation in the surface passivation quality of the poly-Si on oxide layer—corresponding to an increase of the saturation current density J0 by up to a factor of five—causes the degradation of the effective lifetime. Interestingly, the surface passivation fully regenerates under prolonged annealing and finally improves even beyond the initial state. Both the extent of the lifetime degradation and the change in J0 depend on the postprocessing treatment temperature which we varied between 80 and 400 °C. Our results indicate that two different processes are responsible for the degradation and the regeneration. Reference samples which did not receive an RTA treatment show no degradation of the surface passivation quality. The RTA treatment applied therefore triggers the degradation effect. A large improvement of the surface passivation quality under prolonged annealing (e.g., at 400 °C) is observed for all samples examined in this study.
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2019 |
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S. Bordihn, B. Min, R. Peibst, and R. Brendel Modelling of Passivation and Resistance of n-Type poly-Si Layers by Trained Artificial Neural Networks Inproceedings WIP (Hrsg.): Proceedings of the 36th European Photovoltaic Solar Energy Conference and Exhibition, 176-179, Marseille, France, (2019), ISBN: 3-936338-60-4. Abstract | Links | BibTeX | Schlagwörter: Artificial Neural Network, Modelling / Modeling, Polycrystalline Silicon (Si), surface passivation @inproceedings{Bordihn2019b,
title = {Modelling of Passivation and Resistance of n-Type poly-Si Layers by Trained Artificial Neural Networks}, author = {S Bordihn and B Min and R Peibst and R Brendel}, editor = {WIP}, doi = {10.4229/EUPVSEC20192019-2BO.3.1}, isbn = {3-936338-60-4}, year = {2019}, date = {2019-10-23}, booktitle = {Proceedings of the 36th European Photovoltaic Solar Energy Conference and Exhibition}, pages = {176-179}, address = {Marseille, France}, abstract = {This paper studies the passivation quality and sheet resistance of n-type poly-Si on oxide (POLO) layers that we prepare at various post-deposition annealing temperatures. The n-type poly-Si layers are 50 nm-thin and grown on textured and planar Cz Si substrates. The samples are annealed from 880 °C to 1000 °C to transform the amorphous Si to poly-crystalline Si. The surface passivation quality is evaluated after the aforementioned anneal step, after an additional hydrogenation step (induced by Al2O3 capping layers and subsequent low temperature anneal), and after firing at 840 °C peak temperature. The optimal surface passivation quality is found for annealing at 960 °C and hydrogenation, resulting in iVoc-values of 710 mV. The hydrogenation step improves the iVoc by ~20 mV depending on the post-deposition annealing temperature. We find that surface passivation and sheet resistance of the poly-Si layers increased with increasing anneal temperature up to 960 °C and starts to decline above 980 °C. This trend is found to correlate with the amount of in-diffused dopants that depends also on the annealing temperature. We show that artificial neural network based model can serve as a fast tool for predicting layer properties that depend on multiple process parameters. The quality of the modelling is the same as that using the Design of Experiment method. }, keywords = {Artificial Neural Network, Modelling / Modeling, Polycrystalline Silicon (Si), surface passivation}, pubstate = {published}, tppubtype = {inproceedings} } This paper studies the passivation quality and sheet resistance of n-type poly-Si on oxide (POLO) layers that we prepare at various post-deposition annealing temperatures. The n-type poly-Si layers are 50 nm-thin and grown on textured and planar Cz Si substrates. The samples are annealed from 880 °C to 1000 °C to transform the amorphous Si to poly-crystalline Si. The surface passivation quality is evaluated after the aforementioned anneal step, after an additional hydrogenation step (induced by Al2O3 capping layers and subsequent low temperature anneal), and after firing at 840 °C peak temperature. The optimal surface passivation quality is found for annealing at 960 °C and hydrogenation, resulting in iVoc-values of 710 mV. The hydrogenation step improves the iVoc by ~20 mV depending on the post-deposition annealing temperature. We find that surface passivation and sheet resistance of the poly-Si layers increased with increasing anneal temperature up to 960 °C and starts to decline above 980 °C. This trend is found to correlate with the amount of in-diffused dopants that depends also on the annealing temperature. We show that artificial neural network based model can serve as a fast tool for predicting layer properties that depend on multiple process parameters. The quality of the modelling is the same as that using the Design of Experiment method.
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S. Bordihn, B. Min, R. Peibst, and R. Brendel Modelling of Passivation and Resistance of n-Type poly-Si Layers by Trained Artificial Neural Networks Presentation/Poster Marseille, France, 10.09.2019, (36th European Photovoltaic Solar Energy Conference and Exhibition). Abstract | BibTeX | Schlagwörter: Artificial Neural Network, Modelling / Modeling, Polycrystalline Silicon (Si), surface passivation @misc{Bordihn2019,
title = {Modelling of Passivation and Resistance of n-Type poly-Si Layers by Trained Artificial Neural Networks}, author = {S Bordihn and B Min and R Peibst and R Brendel}, year = {2019}, date = {2019-09-10}, address = {Marseille, France}, abstract = {This paper studies the passivation quality and sheet resistance of n-type poly-Si on oxide (POLO) layers that we prepare at various post-deposition annealing temperatures. The n-type poly-Si layers are 50 nm-thin and grown on textured and planar Cz Si substrates. The samples are annealed from 880 °C to 1000 °C to transform the amorphous Si to poly-crystalline Si. The surface passivation quality is evaluated after the aforementioned anneal step, after an additional hydrogenation step (induced by Al2O3 capping layers and subsequent low temperature anneal), and after firing at 840 °C peak temperature. The optimal surface passivation quality is found for annealing at 960 °C and hydrogenation, resulting in iVoc-values of 710 mV. The hydrogenation step improves the iVoc by ~20 mV depending on the post-deposition annealing temperature. We find that surface passivation and sheet resistance of the poly-Si layers increased with increasing anneal temperature up to 960 °C and starts to decline above 980 °C. This trend is found to correlate with the amount of in-diffused dopants that depends also on the annealing temperature. We show that artificial neural network based model can serve as a fast tool for predicting layer properties that depend on multiple process parameters. The quality of the modelling is the same as that using the Design of Experiment method.}, note = {36th European Photovoltaic Solar Energy Conference and Exhibition}, keywords = {Artificial Neural Network, Modelling / Modeling, Polycrystalline Silicon (Si), surface passivation}, pubstate = {published}, tppubtype = {presentation} } This paper studies the passivation quality and sheet resistance of n-type poly-Si on oxide (POLO) layers that we prepare at various post-deposition annealing temperatures. The n-type poly-Si layers are 50 nm-thin and grown on textured and planar Cz Si substrates. The samples are annealed from 880 °C to 1000 °C to transform the amorphous Si to poly-crystalline Si. The surface passivation quality is evaluated after the aforementioned anneal step, after an additional hydrogenation step (induced by Al2O3 capping layers and subsequent low temperature anneal), and after firing at 840 °C peak temperature. The optimal surface passivation quality is found for annealing at 960 °C and hydrogenation, resulting in iVoc-values of 710 mV. The hydrogenation step improves the iVoc by ~20 mV depending on the post-deposition annealing temperature. We find that surface passivation and sheet resistance of the poly-Si layers increased with increasing anneal temperature up to 960 °C and starts to decline above 980 °C. This trend is found to correlate with the amount of in-diffused dopants that depends also on the annealing temperature. We show that artificial neural network based model can serve as a fast tool for predicting layer properties that depend on multiple process parameters. The quality of the modelling is the same as that using the Design of Experiment method.
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J. Schmidt Surface Passivation of Crystalline Silicon Solar Cells: Past, Present and Future Presentation/Poster Leuven, Belgium, 10.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Schlagwörter: surface passivation @misc{Schmidt2019,
title = {Surface Passivation of Crystalline Silicon Solar Cells: Past, Present and Future}, author = {J Schmidt}, year = {2019}, date = {2019-04-10}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {surface passivation}, pubstate = {published}, tppubtype = {presentation} } |
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B. Veith-Wolf, and J. Schmidt Low-Temperature Silicon Surface Passivation for Bulk Lifetime Studies Based on Corona-Charged Al2O3 Presentation/Poster Leuven, Belgium, 08.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Schlagwörter: silicon, surface passivation @misc{Veith-Wolf2019,
title = {Low-Temperature Silicon Surface Passivation for Bulk Lifetime Studies Based on Corona-Charged Al2O3}, author = {B Veith-Wolf and J Schmidt}, year = {2019}, date = {2019-04-08}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {silicon, surface passivation}, pubstate = {published}, tppubtype = {presentation} } |
2018 |
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J. Schmidt, R. Peibst, and R. Brendel Surface passivation of crystalline silicon solar cells: Present and future Artikel Solar Energy Materials and Solar Cells 187 , 39-54, (2018), ISSN: 0927-0248. Abstract | Links | BibTeX | Schlagwörter: Carrier-selective contacts, silicon solar cells, surface passivation @article{Schmidt2018b,
title = {Surface passivation of crystalline silicon solar cells: Present and future}, author = {J Schmidt and R Peibst and R Brendel}, doi = {10.1016/j.solmat.2018.06.047}, issn = {0927-0248}, year = {2018}, date = {2018-12-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {187}, pages = {39-54}, abstract = {In the first part of this paper, we review the developments which led to the present state-of-the-art in the surface passivation of today's industrially predominant dopant-diffused crystalline silicon (c-Si) solar cells, based on dielectric layers such as silicon oxide, silicon nitride, aluminum oxide and stacks thereof. In the second part of this review, we focus on the future developments in the field of c-Si solar cells based on carrier-selective passivation layers. Whereas the dielectric layers are insulating and are hence applied only for passivating the non-contacted areas of the silicon surface, the carrier-selective passivation layers are intended to provide an effective passivation of non-contacted as well as contacted areas of a c-Si solar cell, thereby increasing the efficiency potential of c-Si solar cells significantly. Due to the fact that the carrier-selective layers are implemented in a contact, besides the good passivation properties for minorities, these layers must also provide a good majority carrier transport, i.e. they have to provide a low contact resistance. Both properties, i.e. suppression of minority-carrier recombination as well as good majority-carrier transport, define the selectivity of the carrier-selective contact, which is an important figure of merit for the assessment and comparison of different types of carrier-selective contacts. One very promising type of carrier-selective passivation layer is based on heavily doped polycrystalline silicon layers deposited on a thin silicon oxide layer, the latter providing the excellent passivation while enabling efficient majority-carrier transport via pin-holes and/or tunneling. Moreover, we discuss metal oxides and conductive polymers, which have only recently been applied to c-Si photovoltaics, but seem to have a promising potential as low-cost selective contact materials. We finally compare combinations of the various options of carrier-selective layers concerning their combined selectivities and efficiency potentials.}, keywords = {Carrier-selective contacts, silicon solar cells, surface passivation}, pubstate = {published}, tppubtype = {article} } In the first part of this paper, we review the developments which led to the present state-of-the-art in the surface passivation of today's industrially predominant dopant-diffused crystalline silicon (c-Si) solar cells, based on dielectric layers such as silicon oxide, silicon nitride, aluminum oxide and stacks thereof. In the second part of this review, we focus on the future developments in the field of c-Si solar cells based on carrier-selective passivation layers. Whereas the dielectric layers are insulating and are hence applied only for passivating the non-contacted areas of the silicon surface, the carrier-selective passivation layers are intended to provide an effective passivation of non-contacted as well as contacted areas of a c-Si solar cell, thereby increasing the efficiency potential of c-Si solar cells significantly. Due to the fact that the carrier-selective layers are implemented in a contact, besides the good passivation properties for minorities, these layers must also provide a good majority carrier transport, i.e. they have to provide a low contact resistance. Both properties, i.e. suppression of minority-carrier recombination as well as good majority-carrier transport, define the selectivity of the carrier-selective contact, which is an important figure of merit for the assessment and comparison of different types of carrier-selective contacts. One very promising type of carrier-selective passivation layer is based on heavily doped polycrystalline silicon layers deposited on a thin silicon oxide layer, the latter providing the excellent passivation while enabling efficient majority-carrier transport via pin-holes and/or tunneling. Moreover, we discuss metal oxides and conductive polymers, which have only recently been applied to c-Si photovoltaics, but seem to have a promising potential as low-cost selective contact materials. We finally compare combinations of the various options of carrier-selective layers concerning their combined selectivities and efficiency potentials.
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B. A. Veith-Wolf, S. Schäfer, R. Brendel, and J. Schmidt Solar Energy Materials and Solar Cells 186 , 194-199, (2018), ISSN: 0927-0248. Abstract | Links | BibTeX | Schlagwörter: Aluminum oxide, Auger recombination, charge carrier lifetime, Intrinsic lifetime, silicon, surface passivation @article{Veith-Wolf2018b,
title = {Reassessment of intrinsic lifetime limit in n-type crystalline silicon and implication on maximum solar cell efficiency}, author = {B A Veith-Wolf and S Schäfer and R Brendel and J Schmidt}, doi = {10.1016/j.solmat.2018.06.029}, issn = {0927-0248}, year = {2018}, date = {2018-11-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {186}, pages = {194-199}, abstract = {Unusually high carrier lifetimes are measured by photoconductance decay on n-type Czochralski-grown silicon wafers of different doping concentrations, passivated using plasma-assisted atomic-layer-deposited aluminum oxide (Al2O3) on both wafer surfaces. The measured effective lifetimes significantly exceed the intrinsic lifetime limit previously reported in the literature. Several prerequisites have to be fulfilled to allow the measurement of such high lifetimes on Al2O3-passivated n-type silicon wafers: (i) large-area wafers are required to minimize the impact of edge recombination via the Al2O3-charge-induced inversion layer, (ii) an exceptionally homogeneous Al2O3 surface passivation is required, and (iii) very thick silicon wafers are needed. Based on our lifetime measurements on n-type silicon wafers of different doping concentrations, we introduce a new parameterization of the intrinsic lifetime for n-type crystalline silicon. This new parameterization has implications concerning the maximum reachable efficiency of n-type silicon solar cells, which is larger than assumed before.}, keywords = {Aluminum oxide, Auger recombination, charge carrier lifetime, Intrinsic lifetime, silicon, surface passivation}, pubstate = {published}, tppubtype = {article} } Unusually high carrier lifetimes are measured by photoconductance decay on n-type Czochralski-grown silicon wafers of different doping concentrations, passivated using plasma-assisted atomic-layer-deposited aluminum oxide (Al2O3) on both wafer surfaces. The measured effective lifetimes significantly exceed the intrinsic lifetime limit previously reported in the literature. Several prerequisites have to be fulfilled to allow the measurement of such high lifetimes on Al2O3-passivated n-type silicon wafers: (i) large-area wafers are required to minimize the impact of edge recombination via the Al2O3-charge-induced inversion layer, (ii) an exceptionally homogeneous Al2O3 surface passivation is required, and (iii) very thick silicon wafers are needed. Based on our lifetime measurements on n-type silicon wafers of different doping concentrations, we introduce a new parameterization of the intrinsic lifetime for n-type crystalline silicon. This new parameterization has implications concerning the maximum reachable efficiency of n-type silicon solar cells, which is larger than assumed before.
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B. Veith-Wolf, R. Witteck, A. Morlier, H. Schulte-Huxel, M. R. Vogt, and J. Schmidt Spectra-Dependent Stability of the Passivation Quality of Al2O3/c-Si Interfaces Artikel IEEE Journal of Photovoltaics 8 (1), 96-102, (2018), ISSN: 2156-3381. Abstract | Links | BibTeX | Schlagwörter: Accelerated testing, Al2O3, Aluminum oxide, Carrier lifetime, crystalline silicon, Degradation, Long-term stability, silicon nitride (SiNx), surface passivation, ultraviolet (UV) stability @article{Veith-Wolf2018,
title = {Spectra-Dependent Stability of the Passivation Quality of Al2O3/c-Si Interfaces}, author = {B Veith-Wolf and R Witteck and A Morlier and H Schulte-Huxel and M R Vogt and J Schmidt}, doi = {10.1109/JPHOTOV.2017.2775147}, issn = {2156-3381}, year = {2018}, date = {2018-01-01}, journal = {IEEE Journal of Photovoltaics}, volume = {8}, number = {1}, pages = {96-102}, abstract = {We examine the stability of the c-Si surface passivation quality by spatial atomic-layer-deposited aluminum oxide (Al2O3), plasma-enhanced chemical vapor deposited silicon nitride (SiNx), and Al2O3/SiNx stacks under illumination with two different spectra. The Al2O3-passivated c-Si surfaces annealed at 350 °C show a weak degradation due to UV illumination, with surface recombination velocities (SRVs) of 122 cm/s after receiving a ultraviolet (UV) dose of 275 kWh/m2. Silicon samples passivated with Al2O3 layers that received a fast-firing step show an improvement due to UV illumination with a reduction of the SRVs initially from 14 to 5 cm/s for single Al2O3 layers. For the fired Al2O3 layers the negative fixed charge density increases from -6×1012 cm-2 up to -1.2×1013 cm-2 during UV illumination. We demonstrate that for the SiNx and the fired Al2O3 single layers, photons with energy greater than 3.4 eV are necessary to reduce the passivation quality. In contrast, low-temperature-annealed Al2O3 single layers and nonfired Al2O3/SiNx stacks showed a degradation already under illumination with a halogen lamp. Importantly, we observe a perfectly stable passivation on boron-diffused p+ emitter for fired Al2O3/SiNx stacks featuring a stable saturation current density of 18 fA/cm2 for a p+ sheet resistance of 90 Ω/sq.}, keywords = {Accelerated testing, Al2O3, Aluminum oxide, Carrier lifetime, crystalline silicon, Degradation, Long-term stability, silicon nitride (SiNx), surface passivation, ultraviolet (UV) stability}, pubstate = {published}, tppubtype = {article} } We examine the stability of the c-Si surface passivation quality by spatial atomic-layer-deposited aluminum oxide (Al2O3), plasma-enhanced chemical vapor deposited silicon nitride (SiNx), and Al2O3/SiNx stacks under illumination with two different spectra. The Al2O3-passivated c-Si surfaces annealed at 350 °C show a weak degradation due to UV illumination, with surface recombination velocities (SRVs) of 122 cm/s after receiving a ultraviolet (UV) dose of 275 kWh/m2. Silicon samples passivated with Al2O3 layers that received a fast-firing step show an improvement due to UV illumination with a reduction of the SRVs initially from 14 to 5 cm/s for single Al2O3 layers. For the fired Al2O3 layers the negative fixed charge density increases from -6×1012 cm-2 up to -1.2×1013 cm-2 during UV illumination. We demonstrate that for the SiNx and the fired Al2O3 single layers, photons with energy greater than 3.4 eV are necessary to reduce the passivation quality. In contrast, low-temperature-annealed Al2O3 single layers and nonfired Al2O3/SiNx stacks showed a degradation already under illumination with a halogen lamp. Importantly, we observe a perfectly stable passivation on boron-diffused p+ emitter for fired Al2O3/SiNx stacks featuring a stable saturation current density of 18 fA/cm2 for a p+ sheet resistance of 90 Ω/sq.
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2017 |
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B. A. Veith-Wolf, and J. Schmidt physica status solidi (RRL) – Rapid Research Letters 11 (11), 1700235, (2017), ISSN: 1862-6270, (1700235). Abstract | Links | BibTeX | Schlagwörter: Al2O3, Auger recombination, intrinsic recombination, minority carrier lifetime, silicon, surface passivation @article{Veith-Wolf2017,
title = {Unexpectedly High Minority-Carrier Lifetimes Exceeding 20 ms Measured on 1.4-Ω cm n-Type Silicon Wafers}, author = {B A Veith-Wolf and J Schmidt}, doi = {10.1002/pssr.201700235}, issn = {1862-6270}, year = {2017}, date = {2017-11-01}, journal = {physica status solidi (RRL) – Rapid Research Letters}, volume = {11}, number = {11}, pages = {1700235}, publisher = {WILEY?VCH Verlag Berlin GmbH}, abstract = {We measure very high minority‐carrier lifetimes exceeding 20 ms on 1.4‐Ω cm n‐type Czochralski silicon wafers passivated using plasma‐assisted atomic‐layer‐deposited Al2O3 on both wafer surfaces. The measured maximum effective lifetimes are surprisingly high as they significantly exceed the intrinsic lifetime limit previously reported in the literature. We are able to measure such high lifetimes by realizing an exceptionally homogeneous Al2O3 surface passivation on large‐area samples (12.5 × 12.5 cm2). The importance of the homogeneous passivation is demonstrated by comparison with samples of locally reduced passivation quality.}, note = {1700235}, keywords = {Al2O3, Auger recombination, intrinsic recombination, minority carrier lifetime, silicon, surface passivation}, pubstate = {published}, tppubtype = {article} } We measure very high minority‐carrier lifetimes exceeding 20 ms on 1.4‐Ω cm n‐type Czochralski silicon wafers passivated using plasma‐assisted atomic‐layer‐deposited Al2O3 on both wafer surfaces. The measured maximum effective lifetimes are surprisingly high as they significantly exceed the intrinsic lifetime limit previously reported in the literature. We are able to measure such high lifetimes by realizing an exceptionally homogeneous Al2O3 surface passivation on large‐area samples (12.5 × 12.5 cm2). The importance of the homogeneous passivation is demonstrated by comparison with samples of locally reduced passivation quality.
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V. Titova, B. Veith-Wolf, D. Startsev, and J. Schmidt Energy Procedia 124 (Supplement C), 441 - 447, (2017), ISSN: 1876-6102, (7th International Conference on Silicon Photovoltaics, SiliconPV 2017, 3-5 April 2017, Freiburg, Germany). Abstract | Links | BibTeX | Schlagwörter: atomic layer deposition, electron-selective contact, Silicon solar cell, surface passivation, Titanium oxide @article{Titova2017b,
title = {Effective passivation of crystalline silicon surfaces by ultrathin atomic-layer-deposited TiOx layers}, author = {V Titova and B Veith-Wolf and D Startsev and J Schmidt}, doi = {10.1016/j.egypro.2017.09.272}, issn = {1876-6102}, year = {2017}, date = {2017-09-21}, journal = {Energy Procedia}, volume = {124}, number = {Supplement C}, pages = {441 - 447}, abstract = {We characterize the surface passivation properties of ultrathin titanium oxide (TiOx) films deposited by atomic layer deposition (ALD) on crystalline silicon by means of carrier lifetime measurements. We compare different silicon surface treatments prior to TiOx deposition, such as native silicon oxide (SiOy), chemically grown SiOy and thermally grown SiOy. The best passivation quality is achieved with a native SiOy grown over 4 months and a TiOx layer thickness of 5 nm, resulting in an effective lifetime of 1.2 ms on 1.3 Ωcm p-type float-zone silicon. The measured maximum lifetime corresponds to an implied open-circuit voltage (iVoc) of 710 mV. For thinner TiOx layers the passivation quality is reduced, however, samples passivated with only 2 nm of TiOx still show a lifetime of 612 μs and an iVoc of 694 mV. The contact resistivity of the TiOx including the SiOy interlayer between the silicon wafer and the TiOx is below 0.8 Ωcm2. The combination of excellent surface passivation and low contact resistivity has the potential for silicon solar cells with efficiencies exceeding 26%.}, note = {7th International Conference on Silicon Photovoltaics, SiliconPV 2017, 3-5 April 2017, Freiburg, Germany}, keywords = {atomic layer deposition, electron-selective contact, Silicon solar cell, surface passivation, Titanium oxide}, pubstate = {published}, tppubtype = {article} } We characterize the surface passivation properties of ultrathin titanium oxide (TiOx) films deposited by atomic layer deposition (ALD) on crystalline silicon by means of carrier lifetime measurements. We compare different silicon surface treatments prior to TiOx deposition, such as native silicon oxide (SiOy), chemically grown SiOy and thermally grown SiOy. The best passivation quality is achieved with a native SiOy grown over 4 months and a TiOx layer thickness of 5 nm, resulting in an effective lifetime of 1.2 ms on 1.3 Ωcm p-type float-zone silicon. The measured maximum lifetime corresponds to an implied open-circuit voltage (iVoc) of 710 mV. For thinner TiOx layers the passivation quality is reduced, however, samples passivated with only 2 nm of TiOx still show a lifetime of 612 μs and an iVoc of 694 mV. The contact resistivity of the TiOx including the SiOy interlayer between the silicon wafer and the TiOx is below 0.8 Ωcm2. The combination of excellent surface passivation and low contact resistivity has the potential for silicon solar cells with efficiencies exceeding 26%.
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R. Witteck, H. Schulte-Huxel, B. Veith-Wolf, M. R. Vogt, F. Kiefer, M. Köntges, R. Peibst, and R. Brendel Reducing UV induced degradation losses of solar modules with c-Si solar cells featuring dielectric passivation layers Inproceedings IEEE (Hrsg.): Proceedings of the 44th IEEE Photovoltaic Specialists Conference, Washington, DC, USA, (2017). BibTeX | Schlagwörter: PERC, PV module reliability, solar modules, surface passivation, UV degradation @inproceedings{Witteck2017b,
title = {Reducing UV induced degradation losses of solar modules with c-Si solar cells featuring dielectric passivation layers}, author = {R Witteck and H Schulte-Huxel and B Veith-Wolf and M R Vogt and F Kiefer and M Köntges and R Peibst and R Brendel}, editor = {IEEE}, year = {2017}, date = {2017-07-01}, booktitle = {Proceedings of the 44th IEEE Photovoltaic Specialists Conference}, address = {Washington, DC, USA}, keywords = {PERC, PV module reliability, solar modules, surface passivation, UV degradation}, pubstate = {published}, tppubtype = {inproceedings} } |
2016 |
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B. Veith-Wolf, R. Witteck, A. Morlier, H. Schulte-Huxel, and J. Schmidt Effect of UV illumination on the passivation quality of AlOx/c-Si interfaces Inproceedings IEEE (Hrsg.): 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 1173-1178, Portland, OR, USA, (2016), ISBN: 978-1-5090-2725-5. Abstract | Links | BibTeX | Schlagwörter: Aluminum oxide, Annealing, Carrier lifetime, crystalline silicon, Degradation, Firing, Glass, Lifetime estimation, Lighting, passivation, silicon nitride, surface passivation, UV stability @inproceedings{Veith-Wolf2016,
title = {Effect of UV illumination on the passivation quality of AlOx/c-Si interfaces}, author = {B Veith-Wolf and R Witteck and A Morlier and H Schulte-Huxel and J Schmidt}, editor = {IEEE}, doi = {10.1109/PVSC.2016.7749799}, isbn = {978-1-5090-2725-5}, year = {2016}, date = {2016-06-01}, booktitle = {2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)}, journal = {Proceedings of the 43rd IEEE Photovoltaic Specialists Conference}, pages = {1173-1178}, address = {Portland, OR, USA}, abstract = {We report on the stability of the c-Si surface passivation quality by aluminum oxide (AlOx), silicon nitride (SiNp), and AlOx/SiNy stacks under UV illumination. Low-temperature annealed AlOx shows a weak degradation during UV illumination, with surface recombination velocities (SRVs) of 25 cm/s after a UV dose of 275 kWh/m2. This degradation is less pronounced compared to that of fired SiNy layers with an SRV of 117 cm/s. After a firing step, the AlOx layer show even an improvement during UV illumination, resulting in stabilized SRVs of down to 1 cm/s. The improvement is mainly due to an increase of the negative fixed charge density in the AlOx layer up to a large value of -1.2×10^13 cm-2.}, keywords = {Aluminum oxide, Annealing, Carrier lifetime, crystalline silicon, Degradation, Firing, Glass, Lifetime estimation, Lighting, passivation, silicon nitride, surface passivation, UV stability}, pubstate = {published}, tppubtype = {inproceedings} } We report on the stability of the c-Si surface passivation quality by aluminum oxide (AlOx), silicon nitride (SiNp), and AlOx/SiNy stacks under UV illumination. Low-temperature annealed AlOx shows a weak degradation during UV illumination, with surface recombination velocities (SRVs) of 25 cm/s after a UV dose of 275 kWh/m2. This degradation is less pronounced compared to that of fired SiNy layers with an SRV of 117 cm/s. After a firing step, the AlOx layer show even an improvement during UV illumination, resulting in stabilized SRVs of down to 1 cm/s. The improvement is mainly due to an increase of the negative fixed charge density in the AlOx layer up to a large value of -1.2×10^13 cm-2.
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2015 |
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D. Amkreutz, W. D. Barker, S. Kühnapfel, P. Sonntag, O. Gabriel, S. Gall, U. Bloeck, J. Schmidt, J. Haschke, and B. Rech IEEE Journal of Photovoltaics 5 (6), 1757-1761, (2015). Links | BibTeX | Schlagwörter: Crystallization, Glass, Liquid-phase crystallization (LPC), passivation, Photovoltaic cells, Photovoltaic systems, Polycrystalline silicon, silicon, surface passivation @article{bb,
title = {Liquid-phase crystallized silicon solar cells on glass: increasing the open-circuit voltage by optimized interlayers for n- and p-type absorbers}, author = {D Amkreutz and W D Barker and S Kühnapfel and P Sonntag and O Gabriel and S Gall and U Bloeck and J Schmidt and J Haschke and B Rech}, doi = {10.1109/JPHOTOV.2015.2466434}, year = {2015}, date = {2015-11-01}, journal = {IEEE Journal of Photovoltaics}, volume = {5}, number = {6}, pages = {1757-1761}, keywords = {Crystallization, Glass, Liquid-phase crystallization (LPC), passivation, Photovoltaic cells, Photovoltaic systems, Polycrystalline silicon, silicon, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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D. Zielke, C. Niehaves, W. Lövenich, A. Elschner, M. Hörteis, and J. Schmidt Organic-silicon solar cells exceeding 20% efficiency Artikel Energy Procedia 77 , 331-339, (2015), ISSN: 1876-6102, (5th International Conference on Silicon Photovoltaics, SiliconPV 2015). Links | BibTeX | Schlagwörter: Organic-silicon, PEDOT:PSS, solar cell, surface passivation @article{ZIELKE2015331,
title = {Organic-silicon solar cells exceeding 20% efficiency}, author = {D Zielke and C Niehaves and W Lövenich and A Elschner and M Hörteis and J Schmidt}, doi = {10.1016/j.egypro.2015.07.047}, issn = {1876-6102}, year = {2015}, date = {2015-08-28}, journal = {Energy Procedia}, volume = {77}, pages = {331-339}, note = {5th International Conference on Silicon Photovoltaics, SiliconPV 2015}, keywords = {Organic-silicon, PEDOT:PSS, solar cell, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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B. Veith-Wolf, J. Wang, M. Hannu-Kuure, N. Chen, A. Hadzic, P. Williams, J. Leivo, A. Karkkainen, and J. Schmidt Liquid-phase-deposited siloxane-based capping layers for silicon solar cells Artikel Applied Physics Letters 106 (5), 052104, (2015). Links | BibTeX | Schlagwörter: aluminium, passivation, silicon, Solar Cells, surface passivation @article{Veith-Wolf2015,
title = {Liquid-phase-deposited siloxane-based capping layers for silicon solar cells}, author = {B Veith-Wolf and J Wang and M Hannu-Kuure and N Chen and A Hadzic and P Williams and J Leivo and A Karkkainen and J Schmidt}, doi = {10.1063/1.4907533}, year = {2015}, date = {2015-02-01}, journal = {Applied Physics Letters}, volume = {106}, number = {5}, pages = {052104}, keywords = {aluminium, passivation, silicon, Solar Cells, surface passivation}, pubstate = {published}, tppubtype = {article} } |
2014 |
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D. C. Walter, B. Lim, K. Bothe, V. V. Voronkov, R. Falster, and J. Schmidt Effect of rapid thermal annealing on recombination centres in boron-doped Czochralski-grown silicon Artikel Applied Physics Letters 104 (4), 042111, (2014). Links | BibTeX | Schlagwörter: boron, illumination, nucleation, semiconductor device fabrication, surface passivation @article{Walter2014b,
title = {Effect of rapid thermal annealing on recombination centres in boron-doped Czochralski-grown silicon}, author = {D C Walter and B Lim and K Bothe and V V Voronkov and R Falster and J Schmidt}, doi = {10.1063/1.4863674}, year = {2014}, date = {2014-01-01}, journal = {Applied Physics Letters}, volume = {104}, number = {4}, pages = {042111}, keywords = {boron, illumination, nucleation, semiconductor device fabrication, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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B. Veith, T. Ohrdes, F. Werner, R. Brendel, P. P. Altermatt, N. -P. Harder, and J. Schmidt Injection dependence of the effective lifetime of n-type Si passivated by Al2O3: an edge effect? Artikel Solar Energy Materials and Solar Cells 120 (Part A), 436-440, (2014). Links | BibTeX | Schlagwörter: Aluminum oxide, charge carrier lifetime, modeling, silicon, surface passivation @article{Veith2014,
title = {Injection dependence of the effective lifetime of n-type Si passivated by Al2O3: an edge effect?}, author = {B Veith and T Ohrdes and F Werner and R Brendel and P P Altermatt and N -P Harder and J Schmidt}, doi = {10.1016/j.solmat.2013.06.049}, year = {2014}, date = {2014-01-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {120}, number = {Part A}, pages = {436-440}, keywords = {Aluminum oxide, charge carrier lifetime, modeling, silicon, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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L. E. Black, T. Allen, A. Cuevas, K. R. McIntosh, B. Veith, and J. Schmidt Thermal stability of surface passivation by APCVD Al2O3 Artikel Solar Energy Materials and Solar Cells 120 (Part A), 339-345, (2014). Links | BibTeX | Schlagwörter: Al2O3, silicon, Solar Cells, surface passivation @article{Black2014,
title = {Thermal stability of surface passivation by APCVD Al2O3}, author = {L E Black and T Allen and A Cuevas and K R McIntosh and B Veith and J Schmidt}, doi = {10.1016/j.solmat.2013.05.048}, year = {2014}, date = {2014-01-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {120}, number = {Part A}, pages = {339-345}, keywords = {Al2O3, silicon, Solar Cells, surface passivation}, pubstate = {published}, tppubtype = {article} } |
2013 |
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J. Schmidt, V. Titova, and D. Zielke Organic-silicon heterojunction solar cells: open-circuit voltage potential and stability Artikel Applied Physics Letters 103 (18), 183901, (2013). Links | BibTeX | Schlagwörter: Current density, electric measurements, silicon, Solar Cells, surface passivation @article{Schmidt2013b,
title = {Organic-silicon heterojunction solar cells: open-circuit voltage potential and stability}, author = {J Schmidt and V Titova and D Zielke}, doi = {10.1063/1.4827303}, year = {2013}, date = {2013-10-01}, journal = {Applied Physics Letters}, volume = {103}, number = {18}, pages = {183901}, keywords = {Current density, electric measurements, silicon, Solar Cells, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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J. Bullock, A. Thomson, A. Cuevas, B. Veith, J. Schmidt, and A. Karkkainen physica status solidi (RRL) – Rapid Research Letters 7 (8), 530-533, (2013). Links | BibTeX | Schlagwörter: aluminium oxide, capping films, firing stability, silicon solar cells, surface passivation @article{Bullock2013,
title = {Enhanced rear-side reflection and firing-stable surface passivation of silicon solar cells with capping polymer films}, author = {J Bullock and A Thomson and A Cuevas and B Veith and J Schmidt and A Karkkainen}, doi = {10.1002/pssr.201307200}, year = {2013}, date = {2013-08-01}, journal = {physica status solidi (RRL) – Rapid Research Letters}, volume = {7}, number = {8}, pages = {530-533}, keywords = {aluminium oxide, capping films, firing stability, silicon solar cells, surface passivation}, pubstate = {published}, tppubtype = {article} } |
2012 |
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R. Gogolin, R. Ferre, M. Turcu, and N. P. Harder Silicon heterojunction solar cells: Influence of H2-dilution on cell performance Artikel Solar Energy Materials and Solar Cells 106 , 47-50, (2012), (SiliconPV). Links | BibTeX | Schlagwörter: Amorphous silicon, Hydrogen dilution, Silicon heterojunction solar cells, surface passivation @article{Gogolin2012,
title = {Silicon heterojunction solar cells: Influence of H2-dilution on cell performance}, author = {R Gogolin and R Ferre and M Turcu and N P Harder}, doi = {10.1016/j.solmat.2012.06.001}, year = {2012}, date = {2012-11-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {106}, pages = {47-50}, note = {SiliconPV}, keywords = {Amorphous silicon, Hydrogen dilution, Silicon heterojunction solar cells, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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F. J. Ma, G. G. Samudra, M. Peters, A. G. Aberle, F. Werner, J. Schmidt, and B. Hoex Journal of Applied Physics 112 (5), 054508, (2012). Links | BibTeX | Schlagwörter: carrier lifetimes, double layers, ozone, surface charge, surface passivation @article{Ma2012,
title = {Advanced modeling of the effective minority carrier lifetime of passivated crystalline silicon wafers}, author = {F J Ma and G G Samudra and M Peters and A G Aberle and F Werner and J Schmidt and B Hoex}, doi = {10.1063/1.4749572}, year = {2012}, date = {2012-09-01}, journal = {Journal of Applied Physics}, volume = {112}, number = {5}, pages = {054508}, keywords = {carrier lifetimes, double layers, ozone, surface charge, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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T. Dullweber, S. Gatz, H. Hannebauer, T. Falcon, R. Hesse, J. Schmidt, and R. Brendel Towards 20% efficient large-area screen-printed rear-passivated silicon solar cells* Artikel Progress in Photovoltaics: Research and Applications 20 (6), 630-638, (2012). Links | BibTeX | Schlagwörter: aluminium oxide, local Al contacts, PERC, print on print, Screen printing, silicon dioxide, silicon solar cells, surface passivation @article{Dullweber2012b,
title = {Towards 20% efficient large-area screen-printed rear-passivated silicon solar cells*}, author = {T Dullweber and S Gatz and H Hannebauer and T Falcon and R Hesse and J Schmidt and R Brendel}, doi = {10.1002/pip.1198}, year = {2012}, date = {2012-09-01}, journal = {Progress in Photovoltaics: Research and Applications}, volume = {20}, number = {6}, pages = {630-638}, keywords = {aluminium oxide, local Al contacts, PERC, print on print, Screen printing, silicon dioxide, silicon solar cells, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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B. Veith, T. Dullweber, M. Siebert, C. Kranz, F. Werner, N. -P. Harder, J. Schmidt, B. F. P. Roos, T. Dippell, and R. Brendel Comparison of ICP-AlOx and ALD-Al2O3 Layers for the Rear Surface Passivation of C-Si Solar Cells Artikel Energy Procedia 27 , 379-384, (2012), ISSN: 1876-6102, (Proceedings of the 2nd International Conference on Crystalline Silicon Photovoltaics SiliconPV 2012). Links | BibTeX | Schlagwörter: Aluminum oxide, silicon, Solar Cells, surface passivation @article{VEITH2012379,
title = {Comparison of ICP-AlOx and ALD-Al2O3 Layers for the Rear Surface Passivation of C-Si Solar Cells}, author = {B Veith and T Dullweber and M Siebert and C Kranz and F Werner and N -P Harder and J Schmidt and B F P Roos and T Dippell and R Brendel}, doi = {10.1016/j.egypro.2012.07.080}, issn = {1876-6102}, year = {2012}, date = {2012-08-25}, journal = {Energy Procedia}, volume = {27}, pages = {379-384}, note = {Proceedings of the 2nd International Conference on Crystalline Silicon Photovoltaics SiliconPV 2012}, keywords = {Aluminum oxide, silicon, Solar Cells, surface passivation}, pubstate = {published}, tppubtype = {article} } |
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S. Gatz, J. Müller, T. Dullweber, and R. Brendel Analysis and optimization of the bulk and rear recombination of screen-printed PERC solar cells Artikel Energy Procedia 27 , 95-102, (2012), ISSN: 1876-6102, (Proceedings of the 2nd International Conference on Crystalline Silicon Photovoltaics SiliconPV 2012). Links | BibTeX | Schlagwörter: photovoltaics, silicon, Solar Cells, surface passivation @article{GATZ201295,
title = {Analysis and optimization of the bulk and rear recombination of screen-printed PERC solar cells}, author = {S Gatz and J Müller and T Dullweber and R Brendel}, doi = {10.1016/j.egypro.2012.07.035}, issn = {1876-6102}, year = {2012}, date = {2012-08-25}, journal = {Energy Procedia}, volume = {27}, pages = {95-102}, note = {Proceedings of the 2nd International Conference on Crystalline Silicon Photovoltaics SiliconPV 2012}, keywords = {photovoltaics, silicon, Solar Cells, surface passivation}, pubstate = {published}, tppubtype = {article} } |