Possible Candidates for Impurities in mc‐Si Wafers Responsible for Light‐Induced Lifetime Degradation and Regeneration

Bredemeier, Dennis; Walter, Dominic; Schmidt, Jan

doi:10.1002/solr.201700159

Cited by 67 publications

(39 citation statements)

References 30 publications

(43 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the reduced LeTID could be at least partly explained by a heavier phosphorus emitter, and hence enhanced gettering, in the b-Si cells, 6 although the defect responsible for the degradation is likely another impurity than Fe. 40,41 This explanation supports the conclusion that LeTID is a bulk effect, as suggested previously, 12,23,24 instead of, eg, deterioration of rear surface passivation.…”

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

confidence: 89%

“…The acidic‐textured cells are slightly thicker, ~165 μm, while the non‐textured edges of the b‐Si cells, which experienced SDR instead of acidic‐texturing, have a final thickness between these two (~155 μm). Interestingly, Bredemeier et al reported that wafer thinning reduces LeTID‐causing effective defect density . In our experiments, the non‐textured edges of the SiN x ‐passivated b‐Si cells show more pronounced degradation in the PL map (Figure C) than the thicker acidic‐textured cells (Figure F).…”

Section: Resultsmentioning

confidence: 91%

See 1 more Smart Citation

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

View full text Add to dashboard Cite

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.

show abstract

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

confidence: 89%

Section: Resultsmentioning

confidence: 91%

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

View full text Add to dashboard Cite

show abstract

“…In the following regeneration process, these metal atoms are assumed to diffuse to the surface where they become electrically inactive. In a recent work, the same authors have presented LeTID degradation and regeneration results for lifetime wafers with different thicknesses . It was found that the regeneration process becomes the faster the thinner the cells are, which can be explained by the assumed diffusion process of the unknown metal species to the surface.…”

Section: Performance Parameters Of the Investigated Cellsmentioning

confidence: 99%

“…Whether or not Ni is directly involved in the LeTID degradation/regeneration process in a mechanism discussed in refs. still has to be checked. It could also be possible that, if according to the Bredemeier model the Ni complex decays during degradation and Ni atoms diffuse during regeneration, some of the released Ni atoms precipitate out as NiSi 2 instead of diffusing to the surface.…”

Section: Performance Parameters Of the Investigated Cellsmentioning

confidence: 99%

Nickel Precipitation in Light and Elevated Temperature Degraded Multicrystalline Silicon Solar Cells

2018

View full text Add to dashboard Cite

Multicrystalline silicon passivated emitter and rear contact (PERC) solar cells often show light and elevated temperature-induced degradation (LeTID) followed by a regeneration process. In previous works, it has been found that this degradation/regeneration process can be described by a model including diffusion of still unknown recombination-active point defects to the cell surface. The diffusion coefficient of this unknown species is compatible with interstitial Ni diffusion in Si. In this work, scanning transmission electron microscopy (STEM) and highly sensitive energy dispersive X-ray analysis (EDX) results from altogether 14 positions taken from two cells fabricated from neighboring wafers are evaluated, one of the cells remaining virgin and the other one LeTID degraded. In two of the degraded samples thin Nicontaining platelets are found, which are most probably nickel silicide platelets. This result is an indication that Ni can be involved in the LeTID degradation and regeneration process.

show abstract

“…They reduce the carrier lifetime of silicon materials in both the dissolved state and the precipitated state, and are thus detrimental to silicon solar cells . Knowledge of the metal concentrations in silicon materials is also significant for the studies of other defects, including light and elevated temperature‐induced degradation, decorated crystal defects such as dislocations and grain boundaries, copper‐related light‐induced degradation, boron‐oxygen‐related defects, ring defects, and so on. The metal concentrations in multicrystalline silicon (mc‐Si) ingots have been successfully determined by applying neutron activation analysis in previous studies .…”

mentioning

confidence: 99%

Transition Metals in a Cast‐Monocrystalline Silicon Ingot Studied by Silicon Nitride Gettering

Sun

Liu

Samadi

et al. 2019

Physica Rapid Research Ltrs

View full text Add to dashboard Cite

The concentrations of Cr, Fe, Ni, and Cu in a cast‐monocrystalline silicon ingot grown for solar cell applications are reported. Wafers taken from along the ingot are coated with silicon nitride films and annealed, causing mobile impurities to be gettered to the films. Secondary ion mass spectrometry is applied to measure the metal content in the silicon nitride films. The bulk concentrations of the gettered metals in samples along the ingot are found to be: Cr (3.3 × 1010–3.3 × 1011 cm−3), Fe (3.2 × 1011–2.5 × 1012 cm−3), Ni (1.5 × 1012–1.3 × 1013 cm−3), and Cu (7.1 × 1011–3.2 × 1013 cm−3). For each metal, the lower limit is measured on the wafer from the middle of the ingot, and the higher limit is measured on wafers from the bottom or the top. The results are compared with similar data recently measured on a high‐performance multicrystalline silicon ingot. The results provide insights into the total bulk concentrations of the metals in cast‐grown ingots.

show abstract

Possible Candidates for Impurities in mc‐Si Wafers Responsible for Light‐Induced Lifetime Degradation and Regeneration

Cited by 67 publications

References 30 publications

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

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

Nickel Precipitation in Light and Elevated Temperature Degraded Multicrystalline Silicon Solar Cells

Transition Metals in a Cast‐Monocrystalline Silicon Ingot Studied by Silicon Nitride Gettering

Contact Info

Product

Resources

About