Firing and gettering dependence of effective defect density in material exhibiting LeTID

Skorka, Daniel; Zuschlag, Annika; Hahn, Giso

doi:10.1063/1.5049334

Cited by 9 publications

(10 citation statements)

References 12 publications

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“…These combined maps reveal homogenous LeTID in the good grain areas, with less degradation at the grain boundaries. Such LeTID distribution corresponds to previous LeTID studies of mc-Si PERC cells [5] and lifetime samples [6], [26]. The highest N * LeTID is measured at certain clusters of initially highly recombination-active extended defects, which has also been observed by Niewelt et al [6].…”

Section: A Direct Versus Remote Pecvdsupporting

confidence: 88%

Silicon Nitride Deposition: Impact on Lifetime and Light-Induced Degradation at Elevated Temperature in Multicrystalline Silicon

Lindroos

Zuschlag

Skorka

et al. 2020

IEEE J. Photovoltaics

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Light and elevated temperature induced degradation (LeTID) in multicrystalline (mc) silicon (Si) is known to be sensitive to the silicon nitride (SiN x :H) deposition and the firing, but the reason remains unknown. Three plasma-enhanced chemical vapor deposition (PECVD) tools are used to deposit five different layers, causing significant differences in the initial lifetimes before and after firing. The impact of the different depositions can be effectively compared by replacing the SiN x :H with well-passivating room-temperature iodine ethanol passivation (IE). The IE passivation reveals that the firing of SiN x :H and subsequent bulk hydrogenation leads to a lifetime increase only in the gettered samples. Although the PECVD temperature load affects the bulk lifetime, it does not cause LeTID without SiN x :H deposition. LeTID is only detected in samples fired with SiN x :H, but once the LeTID precursors have been activated, the PECVD layer can be etched and the wafer thinned down without affecting LeTID formation. No link is found between the LeTID defect density and the bulkhydrogenated lifetime. Instead the LeTID defect density appears to decrease with decreasing PECVD deposition time and temperature.

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Section: A Direct Versus Remote Pecvdsupporting

confidence: 88%

Silicon Nitride Deposition: Impact on Lifetime and Light-Induced Degradation at Elevated Temperature in Multicrystalline Silicon

Lindroos

Zuschlag

Skorka

et al. 2020

IEEE J. Photovoltaics

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“…Finally, Figure 3C reveals that the degradation is rather uniform laterally in good grain areas, which is characteristic of LeTID. 12,14 However, defect clusters show slightly stronger LeTID, as reported recently, 37,38 which is even more pronounced in the acidictextured cells (Figure 3E,F).…”

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confidence: 84%

“…Recent studies suggest that P or Al‐gettering can suppress LeTID to some extent, especially in material with low lifetime . Zuschlag et al showed that P‐diffused SiN x ‐passivated mc‐Si lifetime samples experienced only slight degradation, whereas a stronger and faster LeTID was observed in ungettered sister samples .…”

Section: Resultsmentioning

confidence: 92%

“…Recent studies suggest that P or Al-gettering can suppress LeTID to some extent, 17,18 especially in material with low lifetime. 37 Zuschlag et al showed that P-diffused SiN x -passivated mc-Si lifetime samples experienced only slight degradation, whereas a stronger and faster LeTID was observed in ungettered sister samples. 17 Chakraborty et al presented similar results and reported that phosphorus diffusion gettering reduced the concentration of light-induced defects, which were suspected to be Cu, Ni, and Ti, by nearly one order of magnitude.…”

Section: Physical Background For Impact Of B-si On Letidmentioning

confidence: 99%

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Impact of black silicon on light‐ and elevated temperature‐induced degradation in industrial passivated emitter and rear cells

Pasanen

Modanese

Vähänissi

et al. 2018

Progress in Photovoltaics

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Light and elevated‐temperature induced degradation (LeTID) is currently a severe issue in passivated emitter and rear cells (PERC). In this work, we study the impact of surface texture, especially a black silicon (b‐Si) nanostructure, on LeTID in industrial p‐type mc‐Si PERC. Our results show that during standard LeTID conditions the b‐Si cells with atomic‐layer‐deposited aluminum oxide (AlOx) front surface passivation show no degradation despite the presence of a hydrogen‐rich AlOx/SiNx passivation stack on the rear. Furthermore, b‐Si solar cells passivated with silicon nitride (SiNx) on the front lose only 1.5%rel of their initial power conversion efficiency, while the acidic‐textured equivalents degrade by nearly 4%rel under the same conditions. Correspondingly, clear degradation is visible in the internal quantum efficiency (IQE) of the acidic‐textured cells, especially in the ~850 to 1100‐nm wavelength range confirming that the degradation occurs in the bulk, while the IQE remains nearly unaffected in the b‐Si cells. The observations are supported by spatially resolved photoluminescence (PL) maps, which show a clear contrast in the degradation behavior of b‐Si and acidic‐textured cells, especially in the case of SiNx front surface passivation. The PL maps also suggest that the magnitude of LeTID scales with surface area of the texture, rather than wafer thickness that was recently reported, although the b‐Si cells are slightly thinner (140 vs 165 μm). The results indicate that b‐Si has a positive impact on LeTID, and hence, benefits provided by b‐Si are not limited only to the excellent optical properties, as commonly understood.

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“…3. Since a mere decrease of the firing temperature does not erase the difference between LeTID in good grains and at grain boundaries [20], the weak LeTID in PERC B might be linked to the surface passivation deposition. …”

Section: Resultsmentioning

confidence: 99%

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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Firing and gettering dependence of effective defect density in material exhibiting LeTID

Cited by 9 publications

References 12 publications

Silicon Nitride Deposition: Impact on Lifetime and Light-Induced Degradation at Elevated Temperature in Multicrystalline Silicon

Silicon Nitride Deposition: Impact on Lifetime and Light-Induced Degradation at Elevated Temperature in Multicrystalline Silicon

Impact of black silicon on light‐ and elevated temperature‐induced degradation in industrial passivated emitter and rear cells

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

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