Passivation

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Wilhelmus M. M. Kessels - One of the best experts on this subject based on the ideXlab platform.

  • Effective Passivation of silicon surfaces by ultrathin atomic-layer deposited niobium oxide
    Applied Physics Letters, 2018
    Co-Authors: B. Macco, J. H. Deijkers, S. B. Basuvalingam, L. E. Black, W. J.h. Berghuis, Jimmy Melskens, Bas W. H. Van De Loo, Martin Bivour, Martin Hermle, Wilhelmus M. M. Kessels
    Abstract:

    © 2018 Author(s). This letter reports on effective surface Passivation of n-type crystalline silicon by ultrathin niobium oxide (Nb2O5) films prepared by atomic layer deposition (ALD) and subjected to a forming gas anneal at 300 °C. A champion recombination parameter J0 of 20 fA/cm2 and a surface recombination velocity Seff of 4.8 cm/s have been achieved for ultrathin films of 1 nm. The surface pretreatment was found to have a strong impact on the Passivation. Good Passivation can be achieved on both HF-treated c-Si surfaces and c-Si surfaces with a wet-chemically grown interfacial silicon oxide layer. On HF-treated surfaces, a minimum film thickness of 3 nm is required to achieve a high level of surface Passivation, whereas the use of a wet chemically-grown interfacial oxide enables excellent Passivation even for Nb2O5 films of only 1 nm. This discrepancy in Passivation between both surface types is attributed to differences in the formation and stoichiometry of interfacial silicon oxide, resulting in different levels of chemical Passivation. On both surface types, the high level of Passivation of ALD Nb2O5 is aided by field-effect Passivation originating from a high fixed negative charge density of 1-2 × 1012 cm-3. Furthermore, it is demonstrated that the Passivation level provided by 1 nm of Nb2O5 can be further enhanced through light-soaking. Finally, initial explorations show that a low contact resistivity can be obtained using Nb2O5-based contacts. Together, these properties make ALD Nb2O5 a highly interesting building block for high-efficiency c-Si solar cells.

  • role of field effect on c si surface Passivation by ultrathin 2 20 nm atomic layer deposited al2o3
    Applied Physics Letters, 2010
    Co-Authors: N Nick M Terlinden, Van De Mcm Richard Sanden, Gijs G Dingemans, Wilhelmus M. M. Kessels
    Abstract:

    Al2O3 synthesized by plasma-assisted atomic layer deposition yields excellent surface Passivation of crystalline silicon (c-Si) for films down to ∼5 nm in thickness. Optical second-harmonic generation was employed to distinguish between the influence of field-effect Passivation and chemical Passivation through the measurement of the electric field in the c-Si space-charge region. It is demonstrated that this electric field—and hence the negative fixed charge density—is virtually unaffected by the Al2O3 thickness between 2 and 20 nm indicating that a decrease in chemical Passivation causes the reduced Passivation performance for <5 nm thick Al2O3 films.

  • on the c si surface Passivation mechanism by the negative charge dielectric al2o3
    Journal of Applied Physics, 2008
    Co-Authors: Bram Hoex, J. J.h. Gielis, Van De Mcm Richard Sanden, Wilhelmus M. M. Kessels
    Abstract:

    Al2O3 is a versatile high-κ dielectric that has excellent surface Passivation properties on crystalline Si (c-Si), which are of vital importance for devices such as light emitting diodes and high-efficiency solar cells. We demonstrate both experimentally and by simulations that the surface Passivation can be related to a satisfactory low interface defect density in combination with a strong field-effect Passivation induced by a negative fixed charge density Qf of up to 1013 cm−2 present in the Al2O3 film at the interface with the underlying Si substrate. The negative polarity of Qf in Al2O3 is especially beneficial for the Passivation of p-type c-Si as the bulk minority carriers are shielded from the c-Si surface. As the level of field-effect Passivation is shown to scale with Qf2, the high Qf in Al2O3 tolerates a higher interface defect density on c-Si compared to alternative surface Passivation schemes.

  • On the c-Si surface Passivation mechanism by the negative-charge-dielectric Al2 O3
    Journal of Applied Physics, 2008
    Co-Authors: Bram Hoex, J. J.h. Gielis, Mauritius C. M. Van De Sanden, Wilhelmus M. M. Kessels
    Abstract:

    Al2O3 is a versatile high-kappa dielectric that has excellent surface Passivation properties on crystalline Si (c-Si), which are of vital importance for devices such as light emitting diodes and high-efficiency solar cells.We demonstrate both experimentally and by simulations that the surface Passivation can be related to a satisfactory low interface defect density in combination with a strong field-effect Passivation induced by a negative fixed charge density Qf of up to 1013 cm−2 present in the Al2O3 film at the interface with the underlying Si substrate. The negative polarity of Qf in Al2O3 is especially beneficial for the Passivation of p-type c-Si as the bulk minority carriers are shielded from the c-Si surface. As the level of field-effext Passivation is shown to scale with Qf², the high Qf in Al2O3 tolerates a higher interface defect density on c-Si compared to alternative surface Passivation schemes.

Sung-hwan Choi - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Deposition Temperature of SiOx Passivation Layer on the Electrical Performance of a-IGZO TFTs
    IEEE Electron Device Letters, 2012
    Co-Authors: Sung-hwan Choi
    Abstract:

    We investigated the effect of the deposition temperature on the electrical performance of SiOx Passivation layers for amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs). Compared to the time-of-flight secondary ion mass spectroscopy depth profile of the IGZO film with a SiOx Passivation layer deposited at low temperature (150oC ), that with the SiOx film formed at 300oC exhibited the significant migration of metal ions from the IGZO film into the SiOx Passivation layer. These results were attributed to the high-energy ion bombardment on the IGZO channel layer. In order to suppress the interdiffusion of In, Ga, and Zn atoms between the IGZO and Passivation layers, we proposed double SiOx Passivation using different substrate temperatures. It combines the merits of low-temperature (150oC) and high-temperature (300oC) Passivations and compensates for their individual weaknesses. We confirmed the enhanced electrical characteristics and improved reliability of the IGZO TFTs compared to those of the conventional device.

  • Low-Temperature Organic (CYTOP) Passivation for Improvement of Electric Characteristics and Reliability in IGZO TFTs
    IEEE Electron Device Letters, 2012
    Co-Authors: Sung-hwan Choi, Jun-hyuk Jang
    Abstract:

    We proposed and fabricated amorphous indium- gallium-zinc-oxide thin-film transistors (TFTs) employing a novel organic-Passivation layer (CYTOP) that results in low damage and good dielectric quality. The TFT with the CYTOP- Passivation layer successfully exhibited a relatively good electrical characteristic (μsat = 12.3 cm2/V · s) compared with that (μsat = 5.8 cm2/V · s) of the TFT with a SiOx-Passivation layer. The CYTOP-passivated device exhibited relatively good stability (ΔVTH : 2.8 V) under positive bias-temperature stress while the TFTs with the SiOx-Passivation layer showed a 3.3-V ΔVTH shift, respectively. The CYTOP Passivation was performed at low annealing temperature (180οC), and therefore, it is a good candidate for advanced flexible displays.

Armin G. Aberle - One of the best experts on this subject based on the ideXlab platform.

  • Surface Passivation of crystalline silicon solar cells: a review
    Progress in Photovoltaics: Research and Applications, 2000
    Co-Authors: Armin G. Aberle
    Abstract:

    In the 1980s, advances in the Passivation of both cell surfaces led\nto the first crystalline silicon solar cells with conversion efficiencies\nabove 20%. With today's industry trend towards thinner wafers and\nhigher cell efficiency, the Passivation of the front and rear surfaces\nis now also becoming vitally important for commercial silicon cells.\nThis paper presents a review of the surface Passivation methods used\nsince the 1970s, both on laboratory-type as well as industrial cells.\nGiven the trend towards lower-cost (but also lower-quality) Si materials\nsuch as block-cast multicrystalline Si, ribbon Si or thin-film polycrystalline\nSi, the most promising surface Passivation methods identified to\ndate are the fabrication of a p-n junction and the subsequent Passivation\nof the resulting silicon surface with plasma silicon nitride as this\nmaterial, besides reducing surface recombination and reflection losses,\nadditionally provides a very efficient Passivation of bulk defects.\nCopyright � 2000 John Wiley & Sons, Ltd.

Rolf Brendel - One of the best experts on this subject based on the ideXlab platform.

  • High-Efficiency RISE-IBC Solar Cells: Influence of Rear Side-Passivation on pn-Junction Meander Recombination
    28th European Photovoltaic Solar Energy Conference and Exhibition, 2013
    Co-Authors: Robby Peibst, Stephan Kirstein, Nils Peter Harder, Agnes Merkle, TIMOTHY NEUBERT, Frederic Dross, Jochen Schmidt, Paul A. Basore, Rolf Brendel
    Abstract:

    We investigate the influence of the rear side Passivation scheme in our n-type RISE-IBC (Rear Interdigitated Single Evaporation - Interdigitated Backjunction Cell) solar cells. We compare selective rear-side Passivation, i.e. the Passivation of the n+ doped back surface field with thermally grown SiO2 and the Passivation of the p+ doped emitter with PA-ALD (plasma-assisted atomic layer deposition) Al2O3, with full-area Al2O3 rear-side Passivation of both polarities. We show evidence that the choice of rear-side Passivation strongly influences the strength of the recombination where the pn-junction meander surfaces at the rear of the solar cell. While selective rear-side Passivation yields on average 7 mV higher open circuit voltages, the surface recombination at the pnjunction is significant for this Passivation scheme, implying lower pseudo fill factors. The highest energy conversion efficiency of 23.1% is achieved with selective rear-side Passivation. The RISE-IBC solar cells of this study do not have a diffused front-surface field (FSF), but instead rely solely on SiNx Passivation of the textured front side. Nevertheless, very high fill factor values > 82% are obtained. Lateral conductivity of the FSF is obviously not necessarily needed for achieving high fill factors, particularly not for the low-resistivity (< 2 Ω.cm) n-type Cz Si wafers used in this study.

  • Advances in the surface Passivation of silicon solar cells
    Energy Procedia, 2012
    Co-Authors: J. Schmidt, Florian Werner, S. Steingrube, Dimitri Zielke, Birgit Veith, S. Gatz, Thorsten Dullweber, Pietro P. Altermatt, Rolf Brendel
    Abstract:

    The surface Passivation properties of aluminium oxide (Al 2O 3) on crystalline Si are compared with the traditional Passivation system of silicon nitride (SiN x). It is shown that Al 2O 3 has fundamental advantages over SiN x when applied to the rear of p-type silicon solar cells as well as to the p + emitter of n-type silicon solar cells. Special emphasis is paid to the transfer of Al 2O 3 into industrial solar cell production. We compare different Al 2O 3 deposition techniques suitable for mass production such as ultrafast spatial atomic layer deposition, inline plasma-enhanced chemical vapour deposition and reactive sputtering. Finally, we review the most recent cell results with Al 2O 3Passivation and give a brief outlook on the future prospects of Al 2O 3 in silicon solar cell production. © 2011 Published by Elsevier Ltd.

Bram Hoex - One of the best experts on this subject based on the ideXlab platform.

  • Excellent surface Passivation of silicon at low cost: Atomic layer deposited aluminium oxide from solar grade TMA
    2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), 2013
    Co-Authors: Fen Lin, Naomi Nandakumar, Bas Dielissen, Roger Görtzen, Bram Hoex
    Abstract:

    In this work, we investigated the surface Passivation performance of thermal atomic layer deposited Al2O3 films using two different grades of trimethylaluminum (TMA). All films were grown on the InPassion Lab tool from SoLayTec. We demonstrate that the surface Passivation quality is not compromised by the higher impurity concentration in the cheaper solar grade TMA. Excellent Passivation on both p- and n-type silicon surfaces was obtained in a wide process window for samples deposited using both grades of TMA. Remarkably, even a better Passivation quality was obtained by the solar grade TMA, especially on n-type samples. It is therefore demonstrated that excellent surface Passivation by ALD Al2O3 films can be realized using a lower cost precursor.

  • on the c si surface Passivation mechanism by the negative charge dielectric al2o3
    Journal of Applied Physics, 2008
    Co-Authors: Bram Hoex, J. J.h. Gielis, Van De Mcm Richard Sanden, Wilhelmus M. M. Kessels
    Abstract:

    Al2O3 is a versatile high-κ dielectric that has excellent surface Passivation properties on crystalline Si (c-Si), which are of vital importance for devices such as light emitting diodes and high-efficiency solar cells. We demonstrate both experimentally and by simulations that the surface Passivation can be related to a satisfactory low interface defect density in combination with a strong field-effect Passivation induced by a negative fixed charge density Qf of up to 1013 cm−2 present in the Al2O3 film at the interface with the underlying Si substrate. The negative polarity of Qf in Al2O3 is especially beneficial for the Passivation of p-type c-Si as the bulk minority carriers are shielded from the c-Si surface. As the level of field-effect Passivation is shown to scale with Qf2, the high Qf in Al2O3 tolerates a higher interface defect density on c-Si compared to alternative surface Passivation schemes.

  • On the c-Si surface Passivation mechanism by the negative-charge-dielectric Al2 O3
    Journal of Applied Physics, 2008
    Co-Authors: Bram Hoex, J. J.h. Gielis, Mauritius C. M. Van De Sanden, Wilhelmus M. M. Kessels
    Abstract:

    Al2O3 is a versatile high-kappa dielectric that has excellent surface Passivation properties on crystalline Si (c-Si), which are of vital importance for devices such as light emitting diodes and high-efficiency solar cells.We demonstrate both experimentally and by simulations that the surface Passivation can be related to a satisfactory low interface defect density in combination with a strong field-effect Passivation induced by a negative fixed charge density Qf of up to 1013 cm−2 present in the Al2O3 film at the interface with the underlying Si substrate. The negative polarity of Qf in Al2O3 is especially beneficial for the Passivation of p-type c-Si as the bulk minority carriers are shielded from the c-Si surface. As the level of field-effext Passivation is shown to scale with Qf², the high Qf in Al2O3 tolerates a higher interface defect density on c-Si compared to alternative surface Passivation schemes.