Clarification of the relation between the grain structure of industrial grown mc-Si and the area fraction of electrical active defects by means of statistical grain structure evaluation

Lehmann, Toni; Reimann, C.; Meissner, Η.; Friеdrich, J.

doi:10.1016/j.actamat.2015.12.049

Cited by 28 publications

(7 citation statements)

References 14 publications

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“…While the average grain size of the bottom wafers is small, the grain structure of the top wafers is similar to those observed in conventional mc-Si. This is consistent with previous studies by Trempa et al 20) and Lehmann et al 3) Wafers towards the ingot top contain a higher density of dislocation clusters and a lower density of GBs, while the opposite is observed on wafers towards the ingot bottom. Lan et al 5) and Stokkan et al 21) proposed that it is due to fact that the propagation of dislocation networks can be supressed by the increased presence of GBs, which act as alternative sites for stress release during ingot growth.…”

Section: Characterisation Of Crystal Defectssupporting

confidence: 93%

“…Compared to conventionallysolidified mc-Si, HP mc-Si contains smaller grains, larger numbers of grain boundaries (GBs), and a lower number of dislocation clusters. [2][3][4] Lan et al 2,5) suggested that the improvement in their cell efficiency is due to the reduced dislocation density in the material, achieved by growing ingots with smaller grains through nucleation and grain control. Castellanos et al 6) reported a higher lifetime enhancement for HP mc-Si after phosphorus gettering, which they attributed to the lower area fraction of dislocation clusters.…”

Section: Introductionmentioning

confidence: 99%

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Recombination sources in p-type high performance multicrystalline silicon

Sio

Phang

Zheng³

et al. 2017

Jpn. J. Appl. Phys.

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This paper presents a comprehensive assessment of the electronic properties of an industrially grown p-type high performance multicrystalline silicon ingot. Wafers from different positions of the ingot are analysed in terms of their material quality before and after phosphorus diffusion and hydrogenation, as well as their final cell performance. In addition to lifetime measurements, we apply a recently developed technique for imaging the recombination velocity of structural defects. Our results show that phosphorus gettering benefits the intra-grain regions but also activates the grain boundaries, resulting in a reduction in the average lifetimes. Hydrogenation can significantly improve the overall lifetimes, predominantly due to its ability to passivate grain boundaries. Dislocation clusters remain strongly recombination active after all processes. It is found that the final cell efficiency coincides with the varying material quality along the ingot. Wafers toward the ingot top are more influenced by carrier recombination at dislocation clusters, whereas wafers near the bottom are more affected by a combination of their lower intra-grain lifetimes and a greater density of recombination active grain boundaries.

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Section: Characterisation Of Crystal Defectssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Recombination sources in p-type high performance multicrystalline silicon

Sio

Phang

Zheng³

et al. 2017

Jpn. J. Appl. Phys.

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“…Lehmann et al [27] have performed an extensive study of the development of grain orientation, grain boundary misorientation and recombination-active defects throughout the growth of multicrystalline silicon. The results are in principle possible to compare to our study since both the GB fraction of random angle grain boundaries-Σ3 n boundaries in the bottom and top as well as the density of recombination-active defects (dislocation clusters)-are reported.…”

Section: Relationship Between Grain Boundaries and Dislocationsmentioning

confidence: 99%

Investigation of the Grain Boundary Character and Dislocation Density of Different Types of High Performance Multicrystalline Silicon

Stokkan

Song²,

Ryningen

2018

Crystals

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Wafers from three heights and two different lateral positions (corner and centre) of four industrial multicrystalline silicon ingots were analysed with respect to their grain structure and dislocation density. Three of the ingots were non-seeded and one ingot was seeded. It was found that there is a strong correlation between the ratio of the densities of (coincidence site lattice) CSL grain boundaries and high angle grain boundaries in the bottom of a block and the dislocation cluster density higher in the block. In general, the seeded blocks, both the corner and centre block, have a lower dislocation cluster density than in the non-seeded blocks, which displayed a large variation. The density of the random angle boundaries in the corner blocks of the non-seeded ingots was similar to the density in the seeded ingots, while the density in the centre blocks was lower. However, the density of CSL boundaries was higher in all the non-seeded than in the seeded ingots. It appears that both of these grain boundary densities influence the presence of dislocation clusters, and we propose they act as dislocation sinks and sources, respectively. The ability to generate small grain size material without seeding appears to be correlated to the morphology of the coating, which is generally rougher in the corner positions than in the middle. Furthermore, the density of twins and CSL boundaries depends on the growth mode during initial growth and thus on the degree of supercooling. Controlling both these properties is important in order to be able to successfully produce uniform quality high-performance multicrystalline silicon by the advantageous non-seeding method.

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“…IISB contributed much to unravel the mystery of the HPM material and how to achieve it reproducibly . A characterization tool called "Laue scanner" was developed which was extremely useful to study grain orientations and types of grain boundaries of mc silicon on the full wafer scale . This tool was extensively used within the Ph.D. thesis of Toni Lehmann to study and compare the evolution of the grain structure also in very tall conventional and high performance mc silicon ingots .…”

Section: Growth Of Photovoltaic Materialsmentioning

confidence: 99%

Erlangen—An Important Center of Crystal Growth and Epitaxy: Major Scientific Results and Technological Solutions of the Last Four Decades

Friеdrich

Müller

2019

Crystal Research and Technology

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This article describes the historic development of the Erlangen Crystal GrowthLaboratory CGL from its beginnings in 1974 at the chair of Materials of Electrical Engineering (Department of Material Science) of the University of Erlangen-Nuremberg until its current status as a large department "Materials" of the Erlangen Fraunhofer-Institute for Integrated Systems and Device Technology. Essential developments and scientific achievements in the various fields of crystal growth and epitaxy are presented from the early period until today.

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Clarification of the relation between the grain structure of industrial grown mc-Si and the area fraction of electrical active defects by means of statistical grain structure evaluation

Cited by 28 publications

References 14 publications

Recombination sources in p-type high performance multicrystalline silicon

Recombination sources in p-type high performance multicrystalline silicon

Investigation of the Grain Boundary Character and Dislocation Density of Different Types of High Performance Multicrystalline Silicon

Erlangen—An Important Center of Crystal Growth and Epitaxy: Major Scientific Results and Technological Solutions of the Last Four Decades

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