| 1. |
- Adamczyk, Krzysztof, et al.
(author)
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Recombination activity of grain boundaries in high-performance multicrystalline Si during solar cell processing
- 2018
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In: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 123:5, s. 1-6
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Journal article (peer-reviewed)abstract
- In this work, we applied internal quantum efficiency mapping to study the recombination activity of grain boundaries in High Performance Multicrystalline Silicon under different processing conditions. Wafers were divided into groups and underwent different thermal processing, consisting of phosphorus diffusion gettering and surface passivation with hydrogen rich layers. After these thermal treatments, wafers were processed into heterojunction with intrinsic thin layer solar cells. Light Beam Induced Current and Electron Backscatter Diffraction were applied to analyse the influence of thermal treatment during standard solar cell processing on different types of grain boundaries. The results show that after cell processing, most random-angle grain boundaries in the material are well passivated, but small-angle grain boundaries are not well passivated. Special cases of coincidence site lattice grain boundaries with high recombination activity are also found. Based on micro-X-ray fluorescence measurements, a change in the contamination level is suggested as the reason behind their increased activity.
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| 2. |
- Adamczyk, Krzysztof, et al.
(author)
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Recombination Strength of Dislocations in High-Performance Multicrystalline/Quasi-Mono Hybrid Wafers During Solar Cell Processing
- 2018
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In: Physica Status Solidi (a) applications and materials science. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1862-6300 .- 1862-6319. ; 215:2
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Journal article (peer-reviewed)abstract
- Wafers from a hybrid silicon ingot seeded in part for High Performance Multicrystalline, in part for a quasi-mono structure, are studied in terms of the effect of gettering and hydrogenation on their final Internal Quantum Efficiency.The wafers are thermally processed in different groups – gettered and hydrogenated. Afterwards, a low temperature heterojunction with intrinsic thin layer cell process is applied to minimize the impact of temperature. Such procedure made it possible to study the effect of different processing steps on dislocation clusters in the material using the Light Beam Induced Current technique with a high spatial resolution. The dislocation densities are measuredusing automatic image recognition on polished and etched samples. The dislocation recombination strengths are obtained by a correlation of the IQE with the dislocation density according to the Donolato model. Different clusters are compared after different process steps. The results show that for the middle of the ingot, the gettering step can increase the recombination strength of dislocations by one order of magnitude. A subsequent passivation with layers containing hydrogen can lead to a decrease in the recombination strength to levels lower than in ungettered samples.
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| 3. |
- Bertoni, M. I., et al.
(author)
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Nano-XRF and micro-Raman Studies of Metal Impurity Decoration around Dislocations in Multicrystalline Silicon
- 2012
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In: 2012 38TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC). - New York, USA : IEEE. - 9781467300667 ; , s. 1613-1616
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Conference paper (peer-reviewed)abstract
- We push the resolution limits of synchrotron-based nano-X-ray fluorescence mapping below 100 nm to investigate the fundamental differences between benign and deleterious dislocations in multicystalline silicon solar cells. We observe that after processing recombination-active dislocations contain a high degree of nanoscale iron and copper decoration, while recombination-inactive dislocations appear clean. To study the origins of the distinct metal decorations around different dislocations we analyze as-grown samples as well as specimens at different stages of processing. We complement our X-ray studies with micro-Raman mapping to understand the relationship between metallic decoration and stress fields around dislocations.
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| 4. |
- Bertoni, M. I., 1967-, et al.
(author)
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Nanoprobe X-ray fluorescence characterization of defects in large-area solar cells
- 2011
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In: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 4, s. 4252-4257
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Journal article (peer-reviewed)abstract
- The performance of centimeter-sized energy devices is regulated by inhomogeneously distributednanoscale defects. To improve device efficiency and reduce cost, accurate characterization of thesenanoscale defects is necessary. However, the multiscale nature of this problem presentsa characterization challenge, as non-destructive techniques often specialize in a single decade of lengthscales, and have difficulty probing non-destructively beneath the surface of materials with sub-micronspatial resolution. Herein, we push the resolution limits of synchrotron-based nanoprobe X-rayfluorescence mapping to 80 nm, to investigate a recombination-active intragranular defect in industrialsolar cells. Our nano-XRF measurements distinguish fundamental differences between benign anddeleterious dislocations in solar cell devices: we observe recombination-active dislocations to containa high degree of nanoscale iron and copper decoration, while recombination-inactive dislocationsappear clean. Statistically meaningful high-resolution measurements establish a connection betweencommercially relevant materials and previous fundamental studies on intentionally contaminatedmodel defect structures, pointing the way towards optimization of the industrial solar cell process.Moreover, this study presents a hierarchical characterization approach that can be broadly extended toother nanodefect-limited energy systems with the advent of high-resolution X-ray imaging beamlines
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| 5. |
- Borchert, Dietmar, et al.
(author)
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Interaction between process technology and material quality during the processing of multicrystalline silicon solar cells
- 2009
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In: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 20:1, s. 487-492
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Journal article (peer-reviewed)abstract
- Multicrystalline silicon is the most used materialfor the production of silicon solar cells. The quality of the asgrown material depends on the quality of the feedstock andthe crystallization process. Bulk impurities, crystal defectslike dislocations and of course the grain boundaries determinethe material quality and thus the solar cell conversionefficiency. Therefore minority carrier lifetime measurementsare often done to characterize the material quality. Butthe measured values are from limited use because it is knownthat the solar cell process itself can dramatically change theminority carrier lifetime and the solar cell efficiency. In orderto obtain more detailed information of the behaviour ofdifferent defect types additionally high-resolution LBIC(light beam induced current)-measurements have been done.Since LBIC needs a pn-junction for photocurrent generationthe LBIC technique has been combined with the a-Si/c-Siheterojunction cell process, which makes it possible tomanufacture solar cells even from as cut wafers withoutchanging the material quality. With this combination ofmeasurement and preparation techniques it was possible toanalyze the influence of the diffusion process and the firingprocess on the behaviour of the three different defect types: grain boundaries, dislocation networks and bulk impurities.
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