From simulation to experiment: Understanding BO-regeneration kinetics

Wilking, Svenja; Forster, Maxime; Herguth, Axel; Hahn, Giso

doi:10.1016/j.solmat.2015.06.012

Cited by 28 publications

(20 citation statements)

References 25 publications

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“…The impact of the BO related-defect has been extensively studied in p-type boron doped and compensated silicon, as well as in n-type compensated silicon for several years. 8,10,19,20 Recently, the focus has moved to the permanent deactivation of the BO defects [21][22][23][24][25] by annealing under Munzer 21 and Herguth et al 22 reported regeneration of the BO defect in p-type silicon solar cells at 50 to 75 C, and showed that the regenerated cells had similar V oc and efficiencies as the cells before degradation. The cells were stable under illumination of 1 sun intensity over 200 h. However, from Figure 5, it can be seen that the V oc of the regenerated cells cannot be recovered to the initial value.…”

mentioning

confidence: 99%

Upgraded metallurgical-grade silicon solar cells with efficiency above 20%

Zheng

Rougieux

Samundsett

et al. 2016

Applied Physics Letters

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We present solar cells fabricated with n-type Czochralski-silicon wafers grown with strongly compensated 100% upgraded metallurgical-grade feedstock, with efficiencies above 20%. The cells have a passivated boron-diffused front surface, and a rear locally phosphorus-diffused structure fabricated using an etch-back process. The local heavy phosphorus diffusion on the rear helps to maintain a high bulk lifetime in the substrates via phosphorus gettering, whilst also reducing recombination under the rear-side metal contacts. The independently measured results yield a peak efficiency of 20.9% for the best upgraded metallurgical-grade silicon cell and 21.9% for a control device made with electronic-grade float-zone silicon. The presence of boron-oxygen related defects in the cells is also investigated, and we confirm that these defects can be partially deactivated permanently by annealing under illumination. V

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confidence: 99%

Upgraded metallurgical-grade silicon solar cells with efficiency above 20%

Zheng

Rougieux

Samundsett

et al. 2016

Applied Physics Letters

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“…20 In addition, some recent results showed the long-time stability of the permanent deactivation of BO defects in compensated n-Si. 22,24 Combining the modelling results of the charge states, the authors attributed the binding of H and BO defects to covalent binding rather than an ionic interaction. 22…”

Section: B the Reactants' Charge States In The Hydrogenation Of Fe Imentioning

confidence: 98%

“…22,24 Combining the modelling results of the charge states, the authors attributed the binding of H and BO defects to covalent binding rather than an ionic interaction. 22…”

Section: B the Reactants' Charge States In The Hydrogenation Of Fe Imentioning

confidence: 98%

“…9,10 As a closely related topic on the hydrogenation of defects in silicon, the boron-oxygen (BO) defect and its permanent deactivation have been studied in recent years. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] It has been shown that the permanent deactivation of the defect, which occurs under illumination at elevated temperatures, appears to require the presence of hydrogen. [13][14][15][16][17][18][19][20][21]25 In some studies, the permanent deactivation is explained by the significant change of the charge states of monatomic hydrogen under illumination, which accelerates the hydrogen passivation of the defect.…”

Section: Introductionmentioning

confidence: 99%

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Charge states of the reactants in the hydrogen passivation of interstitial iron in P-type crystalline silicon

Sun

Liu

Phang

et al. 2015

Journal of Applied Physics

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Significant reductions in interstitial iron (Fe i ) concentrations occur during annealing Fe-containing silicon wafers with silicon nitride films in the temperature range of 250 C-700 C. The silicon nitride films are known to release hydrogen during the annealing step. However, in co-annealed samples with silicon oxide films, which are hydrogen-lean, changes in the Fe i concentrations were much less significant. The precipitation of Fe i is ruled out as a possible explanation for the significant reductions. The hydrogen passivation of Fe i , which is the complexing of monatomic H and isolated Fe i forming a recombination-inactive hydride, is proposed as the most probable model to explain the reductions. Under the assumption that the reduction is caused by the hydrogenation of Fe i , the reactants' charge states in the hydrogenation reaction are determined by two independent approaches. In the first approach, illumination is found to have a small but detectible impact on the reaction kinetics in the lower temperature range. The dominating reactants' charge states are concluded to be Fe 0 þ H þ as revealed by modelling the injection-dependent charge states of isolated Fe i and monatomic H. In the second approach, the reaction kinetics are fitted with the Arrhenius equation over a large temperature range of 250 C-700 C. A reasonable fit is only obtained when assuming the reacting charge states are Fe 0 þ H þ . This supports the conclusion on the reacting charge states and also gives a value of the activation energy of hydrogenation in the 0.7-0.8 eV range. V C 2015 AIP Publishing LLC. [http://dx.

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“…Increasing the defect formation rate at a given temperature also increases the effectiveness of LID mitigation during illuminated annealing processes (the ratio of passivated to inactive defects). Higher defect formation rates enable the use of higher processing temperatures without sacrificing the effectiveness of LID mitigation [89,93]. The increased temperatures can lead to a further acceleration of the processes due to the exponential dependence of the reaction rates on processing temperature as well as the increase in carrier concentrations and lifetime at higher temperatures [133,135].…”

Section: Role Of Defect Formationmentioning

confidence: 99%

Eliminating Light-Induced Degradation in Commercial p-Type Czochralski Silicon Solar Cells

et al. 2017

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This paper discusses developments in the mitigation of light-induced degradation caused by boron-oxygen defects in boron-doped Czochralski grown silicon. Particular attention is paid to the fabrication of industrial silicon solar cells with treatments for sensitive materials using illuminated annealing. It highlights the importance and desirability of using hydrogen-containing dielectric layers and a subsequent firing process to inject hydrogen throughout the bulk of the silicon solar cell and subsequent illuminated annealing processes for the formation of the boron-oxygen defects and simultaneously manipulate the charge states of hydrogen to enable defect passivation. For the photovoltaic industry with a current capacity of approximately 100 GW peak, the mitigation of boron-oxygen related light-induced degradation is a necessity to use cost-effective B-doped silicon while benefitting from the high-efficiency potential of new solar cell concepts.

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From simulation to experiment: Understanding BO-regeneration kinetics

Cited by 28 publications

References 25 publications

Upgraded metallurgical-grade silicon solar cells with efficiency above 20%

Upgraded metallurgical-grade silicon solar cells with efficiency above 20%

Charge states of the reactants in the hydrogen passivation of interstitial iron in P-type crystalline silicon

Eliminating Light-Induced Degradation in Commercial p-Type Czochralski Silicon Solar Cells

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