Influence of copper contamination on the illuminated forward and dark reverse current‐voltage characteristics of multicrystalline p‐type silicon solar cells

Turmagambetov, Tleuzhan; Dubois, Sébastien; Garandet, J.P.; Martel, Benoît; Enjalbert, N.; Veirman, Jordi; Pihan, É.

doi:10.1002/pssc.201400036

Cited by 15 publications

(7 citation statements)

References 12 publications

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“…In addition, so‐called Sponge‐LID was recently reported . Furthermore, Cu impurity has been found to cause LID (Cu‐LID) in p‐type Si wafers and solar cells . Recently, Cu precipitates were observed in mc‐Si PERCs with strong LID of 15% rel .…”

Section: Introductionmentioning

confidence: 98%

Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

Vahlman¹,

Wagner²,

Wolny³

et al. 2017

Physica Status Solidi (a)

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High-efficiency solar cell designs such as the passivated emitter and rear cell (PERC) raise the quality requirements for silicon substrates, favoring monocrystalline materials. Seedcast quasi-monocrystalline silicon (qm-Si) is a promising alternative for Czochralski (Cz) Si with potential benefits of lower cost and reduced energy footprint. However, the purity and crystalline quality of qm-Si is not on par with Cz-Si, which can cause efficiency losses for example in the form of light-induced degradation (LID). In this contribution, we study the LID phenomena that can be present in qm-Si PERC solar cells, and compare them to the Cz-Si PERC. Degradation and regeneration are analyzed especially from the viewpoint of Cu impurity, which has until very recently been omitted as a source of LID for this device type. Subsequently, differences in LID behavior between qm-Si and Cz-Si are investigated considering the density of dislocations in the bulk. The results imply that slurry-based wafer slicing may introduce contamination that is capable of causing considerable LID in PERC devices fabricated of Si with inherently high defect density.

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Section: Introductionmentioning

confidence: 98%

Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

Vahlman¹,

Wagner²,

Wolny³

et al. 2017

Physica Status Solidi (a)

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“…On the other hand, the choice of light emitter doping also weakens the driving force for the segregation of metallic impurities to the phosphorus-doped region, such that the benefits arising from light doping may be counterbalanced by the incomplete gettering of several metallic impurities, including Cu, as indicated by recent observations of Cu-related LID in industrial silicon solar cells. 18,19 It is therefore crucial to investigate the impact of gettering by lightly doped emitters on the strength of Cu-LID effects.…”

Section: Introductionmentioning

confidence: 99%

Cu gettering by phosphorus-doped emitters in p-type silicon: Effect on light-induced degradation

et al. 2018

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The presence of copper (Cu) contamination is known to cause relevant light-induced degradation (Cu-LID) effects in p-type silicon. Due to its high diffusivity, Cu is generally regarded as a relatively benign impurity, which can be readily relocated during device fabrication from the wafer bulk, i.e. the region affected by Cu-LID, to the surface phosphorus-doped emitter. This contribution examines in detail the impact of gettering by industrially relevant phosphorus layers on the strength of Cu-LID effects. We find that phosphorus gettering does not always prevent the occurrence of Cu-LID. Specifically, air-cooling after an isothermal anneal at 800°C results in only weak impurity segregation to the phosphorus-doped layer, which turns out to be insufficient for effectively mitigating Cu-LID effects. Furthermore, we show that the gettering efficiency can be enhanced through the addition of a slow cooling ramp (-4°C/min) between 800°C and 600°C, resulting in the nearly complete disappearance of Cu-LID effects.

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“…Light‐induced degradation due to Cu impurities has been reported in p‐type PERC cells, with the extent of the performance loss being greater for cells fabricated using multi‐crystalline Si wafers . Copper precipitates have been detected in multi‐crystalline PERC cells for which up to 15% relative efficiency loss was observed after illumination .…”

Section: Challenges For Copper‐plated Silicon Solar Cellsmentioning

confidence: 97%

Challenges facing copper‐plated metallisation for silicon photovoltaics: Insights from integrated circuit technology development

Lennon

Colwell

Rodbell

2018

Progress in Photovoltaics

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Copper‐plated interconnects were widely adopted for volume manufacture of integrated circuits after more than a decade of intensive research to demonstrate that use of Cu would not impact device reliability. However, although Cu‐plated metallisation promises significantly reduced costs for Si photovoltaics, its adoption in manufacturing has not gained the same traction. This review identifies some key challenges facing the introduction of Cu‐plated metallisation for Si photovoltaics. These include the following: (1) increased carrier recombination due to the use of Cu for metal contact formation; (2) reduced module reliability due to adhesion or contact integrity failures; and (3) limited availability of cost‐effective processes and equipment for metal plating. For integrated circuits, Cu's low electrical resistance and high resistance to electromigration provided an impetus for the large investment in process development that was required to realise Cu‐plated interconnects. However, the technical advantages of using Cu for Si solar cell contacts are not as compelling, as solar cells can tolerate larger feature sizes thus reducing the criticality of the contact metal's conductivity and electromigration properties. Additionally, for Si photovoltaics, low cost is paramount, and new challenges arise from the need for modules to absorb light and operate in the field for 25+ years in diverse outdoor climates. However, with the scale of Si photovoltaic manufacturing expected to increase dramatically in the next decade, the use of large quantities of silver for cell metallisation will provide an incentive to address reliability concerns regarding the use of Cu for Si photovoltaic metallisation.

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Influence of copper contamination on the illuminated forward and dark reverse current‐voltage characteristics of multicrystalline p‐type silicon solar cells

Cited by 15 publications

References 12 publications

Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

Cu gettering by phosphorus-doped emitters in p-type silicon: Effect on light-induced degradation

Challenges facing copper‐plated metallisation for silicon photovoltaics: Insights from integrated circuit technology development

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