Understanding the Light-induced Lifetime Degradation and Regeneration in Multicrystalline Silicon

Bredemeier, Dennis; Walter, Dominic; Herlufsen, Sandra; Schmidt, Jan

doi:10.1016/j.egypro.2016.07.060

Cited by 44 publications

(31 citation statements)

References 6 publications

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“…In particular, cobalt is known to form two recombination centers in silicon: one with an electron‐to‐hole capture cross‐section ratio of k = 0.15 and the other one with a value of k = 16 . The second value fits well with our previously published lifetime spectroscopy results, where we determined an electron‐to‐hole capture cross‐section ratio of the light‐induced defect in mc‐Si of k = 20 ± 7 . Hence, our experimental results indicate that cobalt is a very strong candidate.…”

Section: Discussionsupporting

confidence: 89%

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

2017

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We examine the light-induced carrier lifetime degradation and regeneration at elevated temperature in multicrystalline silicon (mc-Si) wafers of different thicknesses. The experimental results show that the thinner the wafer the less pronounced the degradation is and the faster the regeneration takes place. We interpret this result in the framework of a recently proposed defect model, where the lifetime regeneration is attributed to the diffusion of the recombination-active impurity to the wafer surfaces, where it is permanently trapped. Modeling the measured thickness-dependent lifetime evolutions enables us to determine the diffusion coefficient of the impurity to be in the range (5 AE 2) Â 10 À11 cm 2 s À1 at a temperature of 75 C.Comparing the diffusion coefficient extracted from our measurements with data published in the literature allows us to exclude most impurities.Despite the large uncertainties in the diffusion coefficient data reported in the literature, reasonable agreement is only obtained for nickel, cobalt, and hydrogen. One important practical implication of our study is that mc-Si wafers thinner than 120 μm do not suffer from pronounced light-induced lifetime degradation.

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Section: Discussionsupporting

confidence: 89%

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

2017

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“…14 The found Q-factor is, however, similar to findings for a form of LID observed in multicrystalline silicon. 15 Recent results indicate the same effect to also occur in Czochralski grown silicon 16 under similar conditions to those tested in this work.…”

Section: Discussionsupporting

confidence: 62%

“…Either way, defect formation or activation could be related to an interaction with hydrogen followed by its detachment and binding in sinks or a reconfiguration of the defect that causes the lifetime recovery. The insights gathered from our experiments cannot yet confirm or discard whether the degradation is caused by the same defects that are responsible for LID of multicrystalline 15 and Czochralski grown silicon. 16 It should be noted that the lateral inhomogeneities observed by PL imaging obstruct a detailed kinetic analysis of the measured progressions of s eff without an in-depth analysis beyond the scope of this work.…”

Section: Discussionmentioning

confidence: 65%

Light-induced activation and deactivation of bulk defects in boron-doped float-zone silicon

Niewelt

Selinger

Grant

et al. 2017

Journal of Applied Physics

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In this paper, we present new insight in the degradation and subsequent recovery of charge carrier lifetime upon light soaking at 75 °C observed in float-zone silicon wafers. Variations of doping type, dielectric passivation schemes and thermal treatments after layer deposition were performed. The degradation was only observed for p-type float-zone silicon wafers passivated with passivation schemes involving silicon nitride layers. An influence of thermal treatments after deposition was found. N-type wafers did not degrade independent of their passivation scheme. Room temperature re-passivation experiments showed the degradation to affect the wafer bulk, and photoluminescence studies demonstrated fine lateral striations of effective lifetime. We conclude that the degradation is caused by bulk defects that might be related to hydrogen complexes

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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: 99%

“…However, an increase in non-BO related LID has been observed in Cz silicon at peak firing temperatures above $650 C. 33,35 While such effects have been attributed to LeTID, 36,37 the possibility of Cu-LID being responsible for such LID effects has not been specifically precluded in such studies. It must be noted that there exist other empirical differences between LeTID and Cu-LID (e.g., SRH properties 29,38,39 and activation energy of degradation 31,38 ). However, Cu concentrations as low as 10 10 cm À3 have been shown to induce Cu-LID, 40 although the threshold concentration depends on the substrate quality.…”

Section: à3mentioning

confidence: 99%

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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Understanding the Light-induced Lifetime Degradation and Regeneration in Multicrystalline Silicon

Cited by 44 publications

References 6 publications

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

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

Light-induced activation and deactivation of bulk defects in boron-doped float-zone silicon

Rapid thermal anneal activates light induced degradation due to copper redistribution

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