Carbon reaction with levitated silicon – Experimental and thermodynamic approaches

Beaudhuin, M.; Chichignoud, G.; Bertho, P.; Duffar, T.; Lemiti, M.; Zaïdat, K.

doi:10.1016/j.matchemphys.2012.01.023

Cited by 11 publications

(11 citation statements)

References 26 publications

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“…This choice has been made for the two following reasons: i) C propagation inside the silica crucible, that would cause silicon sample pollution, should be avoided. It is well known that C interacts with Si leading either to the precipitation of SiC or to carbon solidification in interstitial positions in the silicon, affecting the nucleation process in both cases . ii) Graphite crucible radiates when heated above 700 °C.…”

Section: Methodsmentioning

confidence: 99%

Undercooling measurement and nucleation study of silicon droplet solidification

Tsoutsouva

Duffar

Girard

et al. 2014

Crystal Research and Technology

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International audienceThe most efficient method to investigate nucleation phenomena is to measure the undercooling temperature at the beginning of the solidification process since it gives information about whether or not a certain substrate favors the heterogeneous nucleation. In this work a suitable experimental setup has been designed and developed for the study of nucleation phenomena, where a silicon droplet is directly placed and melted on a substrate. The melting-solidification process was filmed and the undercooling temperature was simultaneously measured by monochromatic and bichromatic pyrometers. For all the studied substrates the melting process started from the bottom of the sample where there was a contact with the substrate. In the case of zyarock and fused silica substrates, on which we focalize in the present paper, the temperature profile of the silicon sample presented a temperature plateau during melting and a typical cooling curve showing undercooling, recalescence and a plateau denoting that solidification occurred under isothermal conditions. It was also found that the nature of the substrates influences the measured undercooling values and the shape of the solidified silicon droplets

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Section: Methodsmentioning

confidence: 99%

Undercooling measurement and nucleation study of silicon droplet solidification

Tsoutsouva

Duffar

Girard

et al. 2014

Crystal Research and Technology

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“…“Indeed, this high concentration in C associated with metallic impurities contamination can create conditions for growth instability at the solid/liquid interface as seen in and as discussed in section 4.2.1 for a model impurity (tungsten). Moreover, C in the form of SiC precipitates can also act as seeds for parasitic grain nucleation during growth thus modifying the grain structure.” Figure shows the surface of a RST wafer after Sopori etching. We can observe a discontinuity in the growth: the twinned structure is interrupted, leading to the growth of a larger twin‐free grain.…”

Section: Status Of the Rst Technologymentioning

confidence: 99%

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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“…With carbon as the main impurity, the nucleation undercooling went from 300 K, for pure silicon, to a few Kelvin with increasing impurity concentration. The conclusion was that the nucleation of equiaxed silicon grains during growth was triggered by Si 3 N 4 particles rather than SiC [7]. It should be kept in mind, however, that the experiments by Beaudhuin et al [6,7] were levitation drop experiments without any crucible or other solid substrates present.…”

Section: Introductionmentioning

confidence: 98%

“…The conclusion was that the nucleation of equiaxed silicon grains during growth was triggered by Si 3 N 4 particles rather than SiC [7]. It should be kept in mind, however, that the experiments by Beaudhuin et al [6,7] were levitation drop experiments without any crucible or other solid substrates present. The source of carbon leading to nucleation can be either the furnace or the silicon feedstock.…”

Section: Introductionmentioning

confidence: 98%

“…The source of carbon leading to nucleation can be either the furnace or the silicon feedstock. Nucleation undercooling for silicon is strongly dependent on both the carbon and the nitrogen concentration in the melt [6,7]. It is therefore believed that compensated silicon could give rise to an increased nucleation, since the carbon concentration is higher than in the polysilicon feedstock used today.…”

Section: Introductionmentioning

confidence: 99%

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