Influence of Copper Diffusion on Lifetime Degradation in n-type Czochralski Silicon for Solar Cells

Gaspar, Guilherme; Modanese, Chiara; Schøn, Hendrik; Sabatino, Marisa Di; Arnberg, L.; Øvrelid, Eivind

doi:10.1016/j.egypro.2015.07.084

Cited by 10 publications

(2 citation statements)

References 14 publications

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“…As the plating time of Cu is exceeding the Ni plating time, the wetted area is greater during Cu plating. Therefore, there is a risk of Cu deposition directly within the LCO, which should be avoided due to strong Cu diffusion into silicon [24] so that the n-type doped side should be plated at first. As long as the wrap around is not avoided, plating of the n-doped side first followed by the p-doped side is suggested, as displayed in Fig.…”

Section: Contact Modifications Due To Electrolyte Wrap-aroundmentioning

confidence: 99%

Direct Contact Electroplating Sequence Without Initial Seed Layer for Bifacial TOPCon Solar Cell Metallization

Grübel

Cimiotti

Schmiga

et al. 2021

IEEE J. Photovoltaics

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The metallization of bifacial tunneling oxide and passivating contacts (TOPCon) solar cells without initial metal seed layer by electroplating of Ni/Cu/Ag is demonstrated. The presented approach allows a lead-free metallization with narrow contact geometries and low contact resistivity. A metal plate provides electrical contact to the silicon via micrometer size laser contact openings and allows electroplating of bifacial TOPCon solar cells using industrial type inline plating tools without the need of a previously applied seed layer. Challenges such as direct contacting of silicon and dissolution of contacts are identified, and potential solutions are discussed. An optimized process sequence is developed and with this approach a solar cell efficiency of 22.5% is demonstrated on industrial bifacial TOPCon solar cells reaching the same level as the screen-printed reference solar cells. Index Terms-Forward bias plating (FBP), light induced plating (LIP), passivating contacts, silicon solar cells, tunneling oxide and passivating contacts (TOPCon). I. INTRODUCTION S OLAR cells featuring carrier selective contacts such as tunneling oxide and passivating contacts (TOPCon) consisting of a thin oxide layer and a highly doped poly-Si, which significantly reduces contact recombination have attracted an increased interest lately. Their potential was already shown on an n-type both sided contacts lab cell by Richter et al. [1] with 25.8% efficiency [2] and single-sided contacted IBC lab cell by Haase et al. [3] with 26.1% both on 4 cm² sample size. The industrial implementation referred as i-TOPCon featuring a boron emitter passivated by AlO x/ SiN x on the front side and Manuscript

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Section: Contact Modifications Due To Electrolyte Wrap-aroundmentioning

confidence: 99%

Direct Contact Electroplating Sequence Without Initial Seed Layer for Bifacial TOPCon Solar Cell Metallization

Grübel

Cimiotti

Schmiga

et al. 2021

IEEE J. Photovoltaics

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show abstract

“…However, because of the presence of grown-in structural defects, the properties of mc-Si solar cells are not as good as those of Czochralski silicon (CZ-Si) cells. Metal impurities, especially Fe-related impurities are also key factors to solar cell performance [5][6][7][8][9] . For instance, mc-Si contains high concentrations of iron, typically in the range of 10 14 to 10 16 cm −3 .…”

Section: Introductionmentioning

confidence: 99%

Collaborative R&D between multicrystalline silicon ingots and battery efficiency improvement—effect of shadow area in multicrystalline silicon ingots on cell efficiency

et al. 2018

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We characterized strip-like shadows in cast multicrystalline silicon (mc-Si) ingots. Blocks and wafers were analyzed using scanning infrared microscopy, photoluminescence spectroscopy, laser scanning confocal microscopy, field-emission scanning electron microscopy, X-ray energy-dispersive spectrometry, and microwave photoconductivity decay technique. The effect on solar cell performance is discussed. The results show that the non-microcrystalline shadow region in Si ingots consists of precipitates of Fe, O, and C. The size of these Fe–O–C precipitates found at the shadow region is ~25 μm. Fe–O–C impurities can slightly reduce the minority carrier lifetime of the wafers while severely decrease in shunt resistance, leading to the increase in reverse current of the solar cells and degradation in cell efficiency.

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On copper diffusion in silicon measured by glow discharge mass spectrometry

et al. 2014

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Copper contamination occurs frequently in silicon for photovoltaic applications due to its very fast diffusion coupled with a low solid solubility, especially at room temperature. The combination of these properties exerts a challenge on the direct analysis of Cu bulk concentration in Si by sputtering techniques like glow discharge mass spectrometry (GDMS). This work aims at addressing the challenges in quantitative analysis of fast diffusing elements in Si matrix by GDMS. N-type, monocrystalline (Czochralski) silicon samples were intentionally contaminated with Cu after solidification and consequently annealed at 900 °C to ensure a homogeneous distribution of Cu in the bulk. The samples were quenched after annealing to control the extent of the diffusion to the surface prior to the GDMS analyses, which were carried out at different time intervals from within few minutes after cooling onward. The Cu profiles were measured by high-resolution GDMS operating in a continuous direct current mode, where the integration step length was set to ∼0.5 μm over a total sputtered depth of 8-30 μm. The temperature of the samples during the GDMS analyses was also measured in order to evaluate the diffusion. The Cu contamination of n-type Si samples was observed to be highly material dependent. The practical impact of Cu out-diffusion on the calculation of the relative sensitivity factor (RSF) of Cu in Si is discussed.

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Influence of Copper Diffusion on Lifetime Degradation in n-type Czochralski Silicon for Solar Cells

Cited by 10 publications

References 14 publications

Direct Contact Electroplating Sequence Without Initial Seed Layer for Bifacial TOPCon Solar Cell Metallization

Direct Contact Electroplating Sequence Without Initial Seed Layer for Bifacial TOPCon Solar Cell Metallization

Collaborative R&D between multicrystalline silicon ingots and battery efficiency improvement—effect of shadow area in multicrystalline silicon ingots on cell efficiency

On copper diffusion in silicon measured by glow discharge mass spectrometry

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