Rapid Stabilization of High-Performance Multicrystalline P-type Silicon PERC Cells

Chan, Catherine; Payne, D.N.; Hallam, Brett; Abbott, Malcolm; Fung, Tsun Hang; Wenham, Alison; Tjahjono, Budi; Wenham, Stuart

doi:10.1109/jphotov.2016.2606704

Cited by 124 publications

(102 citation statements)

References 15 publications

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“…Furthermore, several other studies [29][30][31][32] have consistently reported that the magnitude of LeTID increases with peak firing temperature, with peak temperatures 650 C leading to little or no LeTID, while temperatures between 700 C and 950 C trigger degradation. These trends in degradation behaviour with firing temperature and cooling rate correlate well with the present study.…”

Section: à3mentioning

confidence: 87%

Rapid thermal anneal activates light induced degradation due to copper redistribution

Nampalli

Laine

Colwell

et al. 2018

Applied Physics Letters

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While it is well known that copper impurities can be relatively easily gettered from the silicon bulk to the phosphorus or boron–doped surface layers, it has remained unclear how thermally stable the gettering actually is. In this work, we show experimentally that a typical rapid thermal anneal (RTA, a few seconds at 800 °C) used commonly in the semiconductor and photovoltaic industries is sufficient to release a significant amount of Cu species from the phosphorus-doped layer to the wafer bulk. This is enough to activate the so-called copper-related light-induced degradation (Cu-LID) which results in significant minority carrier lifetime degradation. We also show that the occurrence of Cu-LID in the wafer bulk can be eliminated both by reducing the RTA peak temperature from 800 °C to 550 °C and by slowing the following cooling rate from 40–60 °C/s to 4 °C/min. The behavior is similar to what is reported for Light and Elevated Temperature degradation, indicating that the role of Cu cannot be ignored when studying other LID phenomena. Numeric simulations describing the phosphorus diffusion and the gettering process reproduce the experimental trends and elucidate the underlying physical mechanisms.

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Section: à3mentioning

confidence: 87%

Rapid thermal anneal activates light induced degradation due to copper redistribution

Nampalli

Laine

Colwell

et al. 2018

Applied Physics Letters

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“…to above 10% rel. , depending on the wafer bulk and the solar cell processing [1][2][3][4][5][6][7][8]. LeTID formation is particularly sensitive to the peak temperature [3] and the cooling profile of the firing step [4].…”

Section: Introductionmentioning

confidence: 99%

“…, depending on the wafer bulk and the solar cell processing [1][2][3][4][5][6][7][8]. LeTID formation is particularly sensitive to the peak temperature [3] and the cooling profile of the firing step [4]. PERC cells that have been fired above 675°C [3] and cooled down rapidly show strong homogenous LeTID in the mc grains, with lower defect densities at the grain boundaries [6].…”

Section: Introductionmentioning

confidence: 99%

“…LeTID formation is particularly sensitive to the peak temperature [3] and the cooling profile of the firing step [4]. PERC cells that have been fired above 675°C [3] and cooled down rapidly show strong homogenous LeTID in the mc grains, with lower defect densities at the grain boundaries [6]. Slower cooling in RTP furnaces has resulted in less but still homogenous degradation [4].…”

Section: Introductionmentioning

confidence: 99%

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Light-induced degradation variation in industrial multicrystalline PERC silicon solar cells

Lindroos¹,

Zuschlag²,

Carstensen³

et al. 2018

AIP Conference Proceedings

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, and Giso Hahn giso.hahn@uni-konstanz.deAbstract. Light and elevated temperature induced degradation (LeTID) varies significantly in multicrystalline PERC silicon solar cells, depending mainly on the solar cell processes. We show that despite high firing temperatures, LeTID can manifest itself in two different ways: 1) strong LeTID in good grains (jsc and Voc losses >7%rel.), or 2) low LeTID in good grains with stronger LeTID at dislocation clusters. Such LeTID at dislocation clusters is not only caused by a bulk recombination increase but also by an increased back-surface recombination velocity.

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“…27 Transition to the PERC structure has also brought forward a new light-induced defect in mc-Si, whose origin is currently under debate. [28][29][30][31][32][33][34][35][36][37][38] Identification and understanding of the above sources of LID and their underlying defect mechanisms is fundamental when considering methods for their mitigation in solar cells. Published by AIP Publishing.…”

Section: Introductionmentioning

confidence: 99%

Modeling of light-induced degradation due to Cu precipitation in p-type silicon. I. General theory of precipitation under carrier injection

Vahlman

Haarahiltunen

Kwapil

et al. 2017

Journal of Applied Physics

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Copper contamination causes minority carrier lifetime degradation in p-type silicon bulk under illumination, leading to considerable efficiency losses in affected solar cells. Although the existence of this phenomenon has been known for almost two decades, ambiguity prevails about the underlying defect mechanism. In Paper I of this two-part contribution, we propose the first comprehensive mathematical model for Cu-related light-induced degradation in p-type silicon (Cu-LID). The model is based on the precipitation of interstitial Cu ions, which is assumed to be kinetically limited by electrostatic repulsion from the growing Cu precipitates. Hence, growth and dissolution rates of individual Cu precipitates are derived from the drift-diffusion equation of interstitial Cu and used in a kinetic precipitation model that is based on chemical rate equations. The kinetic model is interlinked to a Schottky junction model of metallic precipitates in silicon, enabling accurate calculation of the injection-dependent electric field enclosing the precipitates, as well as the precipitate-limited minority carrier lifetime. It is found that a transition from darkness to illuminated conditions can cause an increase in the kinetics of precipitation by five orders of magnitude. Since our approach enables a direct connection between the time evolution of precipitate size-density distribution and minority carrier lifetime degradation under illumination, a procedure for calculating the Cu-LID-related lifetime as a function of illumination time is included at the end of this article. The model verification with experiments is carried out in Paper II of this contribution along with a discussion of the kinetic and energetic aspects of Cu-LID. Published by AIP Publishing.

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Rapid Stabilization of High-Performance Multicrystalline P-type Silicon PERC Cells

Cited by 124 publications

References 15 publications

Rapid thermal anneal activates light induced degradation due to copper redistribution

Rapid thermal anneal activates light induced degradation due to copper redistribution

Light-induced degradation variation in industrial multicrystalline PERC silicon solar cells

Modeling of light-induced degradation due to Cu precipitation in p-type silicon. I. General theory of precipitation under carrier injection

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