Influence of defect type on hydrogen passivation efficacy in multicrystalline silicon solar cells

Bertoni, Mariana I.; Hudelson, S.; Newman, Bonna; Fenning, David P.; Dekkers, Harold; Cornagliotti, Emanuele; Zuschlag, Annika; Micard, Gabriel; Hahn, Giso; Coletti, Gianluca; Lai, Barry; Buonassisi, Tonio

doi:10.1002/pip.1008

Cited by 36 publications

(18 citation statements)

References 23 publications

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“…On the contrary, no link between the twin boundary density and the electrical activity was observed. These observations are consistent with and , where it was shown that it is the presence of dislocations along the twin boundaries that limits the ability of hydrogen to passivate them. This depends on the coincidence site lattice of the twin boundaries, the Σ3 being the less favourable to dislocation occurrence.…”

Section: Status Of the Rst Technologysupporting

confidence: 88%

Fast growth of thin multi‐crystalline silicon ribbons by the RST method

Heilbronn¹,

Moro²,

Jolivet³

et al. 2014

Crystal Research and Technology

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The ribbon on sacrificial template (RST) process is a ribbon direct-wafering technology with specific ability for high throughput and thin multicrystalline wafer production, in the range of 60-140 μm. Mechanical and electrical properties of the RST material were investigated. Ball on ring and four-point bending tests showed good fracture stress values up to 260 MPa. The conversion efficiency potential for passivated emitter and rear cells (PERC) made out from the RST material, around 16%, is shown to be limited by defects reducing minority carrier lifetime. The interaction between impurities, such as C and transitions metals, with structural defects such as dislocations, results in highly recombinative areas in RST wafers. A model is proposed which shows that the carbon substrate is an important source of carbon contamination in the silicon melt during the growth of the ribbon. This high C contamination can be accompanied by transition metal contamination and can have an influence on the growth stability and on the generation of structural defects, especially if C accumulates in a boundary layer just above the growth interface. The study of the segregation of Sb indicates that the process conditions are close to the case of the diffusive regime near the solid/liquid interface, with a boundary layer thickness of about 70 μm.

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Section: Status Of the Rst Technologysupporting

confidence: 88%

Fast growth of thin multi‐crystalline silicon ribbons by the RST method

Heilbronn¹,

Moro²,

Jolivet³

et al. 2014

Crystal Research and Technology

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show abstract

“…In good agreement with the l-XRF of Buonassisi et al, 44 they found that higher order CSL GB character and higher metal contamination lead to higher EBIC contrast. Bertoni et al 61 found higher GB recombination activity after hydrogenation strongly depended on the dislocation density and/or faceting along the GB.…”

Section: Appendix B: Assessment Of Assumptions For Comparisons Of Expmentioning

confidence: 99%

Precipitated iron: A limit on gettering efficacy in multicrystalline silicon

Fenning

Hofstetter

Bertoni

et al. 2013

Journal of Applied Physics

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A phosphorus diffusion gettering model is used to examine the efficacy of a standard gettering process on interstitial and precipitated iron in multicrystalline silicon. The model predicts a large concentration of precipitated iron remaining after standard gettering for most as-grown iron distributions. Although changes in the precipitated iron distribution are predicted to be small, the simulated post-processing interstitial iron concentration is predicted to depend strongly on the as-grown distribution of precipitates, indicating that precipitates must be considered as internal sources of contamination during processing. To inform and validate the model, the iron distributions before and after a standard phosphorus diffusion step are studied in samples from the bottom, middle, and top of an intentionally Fe-contaminated laboratory ingot. A census of iron-silicide precipitates taken by synchrotron-based X-ray fluorescence microscopy confirms the presence of a high density of iron-silicide precipitates both before and after phosphorus diffusion. A comparable precipitated iron distribution was measured in a sister wafer after hydrogenation during a firing step. The similar distributions of precipitated iron seen after each step in the solar cell process confirm that the effect of standard gettering on precipitated iron is strongly limited as predicted by simulation. Good agreement between the experimental and simulated data supports the hypothesis that gettering kinetics is governed by not only the total iron concentration but also by the distribution of precipitated iron. Finally, future directions based on the modeling are suggested for the improvement of effective minority carrier lifetime in multicrystalline silicon solar cells.

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“…Preparation procedures have been reported elsewhere [8]. The electrical performance was characterized using laser beam-induced current (SR-LBIC) [9] at the University of Konstanz at 833 nm and 910 nm.…”

Section: Resultsmentioning

confidence: 99%

Impact of defect type on hydrogen passivation effectiveness in multicrystalline silicon solar cells

Bertoni

Hudelson

Newman

et al. 2010

2010 35th IEEE Photovoltaic Specialists Conference

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In this work we examine the effectiveness of hydrogen passivation at grain boundaries as a function of defect type and microstructure in multicrystalline silicon. We analyze a specially prepared solar cell with alternating mm-wide bare and SiNx-coated stripes using laser beaminduced current (LBIC), electron backscatter diffraction (EBSD), synchrotron-based X-ray fluorescence microscopy (µ-XRF), and defect etching to correlate preand post-hydrogenation recombination activity with grain boundary character, density of iron-silicide nanoprecipitates, and dislocations. This study reveals that the microstructure of boundaries that passivate well and those that do not differ mostly in the character of the dislocations along the grain boundary, while iron silicide precipitates along the grain boundaries (above detection limits) were found to play a less significant role.

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Influence of defect type on hydrogen passivation efficacy in multicrystalline silicon solar cells

Cited by 36 publications

References 23 publications

Fast growth of thin multi‐crystalline silicon ribbons by the RST method

Fast growth of thin multi‐crystalline silicon ribbons by the RST method

Precipitated iron: A limit on gettering efficacy in multicrystalline silicon

Impact of defect type on hydrogen passivation effectiveness in multicrystalline silicon solar cells

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