Infrared birefringence imaging of residual stress and bulk defects in multicrystalline silicon

Ganapati, Vidya; Schoenfelder, Stephan; Castellanos, Sergio; Oener, Sebastian Z.; Koepge, R.; Sampson, Aaron L.; Marcus, Matthew A.; Lai, Barry; Morhenn, Humphrey; Hahn, Giso; Bagdahn, J.; Buonassisi, Tonio

doi:10.1063/1.3468404

Cited by 57 publications

(27 citation statements)

References 102 publications

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“…Although we did not have the microscope with a setup to observe amount of strain and stress as reported in Refs. , we were able to observe strain distribution. We observed surface profiles using laser microscopy, which measures the surface roughness by detecting of focus points of a laser.…”

Section: Methodsmentioning

confidence: 85%

Excess carrier lifetime and strain distributions in a 3C-SiC wafer grown on an undulant Si substrate

Kato

Yoshida

Ichimura

et al. 2013

Phys. Status Solidi A

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In this study, we have used the microwave photoconductivity decay method to map excess carrier lifetimes in a n‐type 3C‐SiC wafer grown on an undulant Si substrate. We compared these lifetime maps with the distributions of strains and defects, which were observed using optical microscopy, Raman spectroscopy and pit distributions after molten NaOH etching. We found that excess carrier lifetimes in strained regions, which exhibit high densities of defects, are short. We also found that carrier lifetimes in strained regions at the cross sections of the 3C‐SiC wafer are short. These results suggest that defects and strains in the wafer exhibit distributions similar to those of shortened carrier lifetimes. Excess carrier lifetime map for a 3C‐SiC wafer.

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Section: Methodsmentioning

confidence: 85%

Excess carrier lifetime and strain distributions in a 3C-SiC wafer grown on an undulant Si substrate

Kato

Yoshida

Ichimura

et al. 2013

Phys. Status Solidi A

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“…Metallic and other impurities such as oxygen, carbon, and nitrogen are readily available in the furnace and a horizontal growth component could lead to increased segregation and probability of precipitation within the gaps [18,19]. As precipitates usually have different thermal expansion coefficients than the surrounding silicon matrix, they can therefore lead to additional stress development during cooling of the ingot.…”

Section: Dislocations Below the Seed Interfacementioning

confidence: 99%

Structure and dislocation development in mono‐like silicon

Ekstrøm

Stokkan

Søndenå

et al. 2015

Physica Status Solidi (a)

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The current paper investigates the structure of low-lifetime areas observed in a < 110 >-oriented mono-like silicon ingot grown from monocrystalline seeds. These areas are related to dislocation clusters forming at seed junctions and several generation mechanisms are discussed. Dislocations generated due to physical contact between seeds could only be completely avoided by introducing gaps between the seeds. Large gaps were, however, found to suffer from alternative generation processes not found in small gaps. Dislocations generated in the seeds and in peripheral grains does not necessarily move in to the main crystal and low-lifetime areas are mainly related to dislocations generated above the seeding structure. Dislocations are found to form clusters aligning along < 111 >-directions and are proposed to happen by glide on {111}-planes from the boundary plane between two seed crystals. The extent of low-lifetime areas and corresponding dislocation clusters, for junctions containing no or small gaps, appear to mainly depend on the misorientation between seeds and by attaining sufficiently low misorientation the high bulk lifetime can be retained also at the junctions. Analysis of the misorientations along principal axes indicates that larger misorientations can be tolerated if the misorientation is limited to a single tilt axis

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“…The strain field of dislocations influences its recombination activity [11]. Consequently, additional studies on the electrical performance of these defects were performed using high spatial resolution LBIC analysis (better than 1 |im) on solar cells manufactured from different Gn-based wafers.…”

Section: Towards the Seed Recyclingmentioning

confidence: 99%

About the origin of low wafer performance and crystal defect generation on seed-cast growth of industrial mono-like silicon ingots

Guerrero

Parra

Carballo

et al. 2012

Prog. Photovolt: Res. Appl.

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The era of the seed-cast grown monocrystalline-based silicon ingots is coming. Mono-like, pseudomono or quasimono wafers are product labels that can be nowadays found in the market, as a critical innovation for the photovoltaic industry. They integrate some of the most favorable features of the conventional silicon substrates for solar cells, so far, such as the high solar cell efficiency offered by the monocrystalline Czochralski-Si (Cz-Si) wafers and the lower cost, high productivity and full square-shape that characterize the well-known multicrystalline casting growth method. Nevertheless, this innovative crystal growth approach still faces a number of mass scale problems that need to be resolved, in order to gain a deep, 100% reliable and worldwide market: (i) extended defects formation during the growth process; (ii) optimization of the seed recycling; and (iii) parts of the ingots giving low solar cells performance, which directly affect the production costs and yield of this approach. Therefore, this paper presents a series of casting crystal growth experiments and characterization studies from ingots, wafers and cells manufactured in an industrial approach, showing the main sources of crystal defect formation, impurity enrichment and potential consequences at solar cell level. The previously mentioned technological drawbacks are directly addressed, proposing industrial actions to pave the way of this new wafer technology to high efficiency solar cells.

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Infrared birefringence imaging of residual stress and bulk defects in multicrystalline silicon

Cited by 57 publications

References 102 publications

Excess carrier lifetime and strain distributions in a 3C-SiC wafer grown on an undulant Si substrate

Excess carrier lifetime and strain distributions in a 3C-SiC wafer grown on an undulant Si substrate

Structure and dislocation development in mono‐like silicon

About the origin of low wafer performance and crystal defect generation on seed-cast growth of industrial mono-like silicon ingots

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