Numerical Analysis of mc-Si Crystal Growth

2009 ◽  
Vol 156-158 ◽  
pp. 193-198 ◽  
Author(s):  
Koichi Kakimoto ◽  
Hitoshi Matsuo ◽  
Syo Hisamatsu ◽  
Birava Ganesh ◽  
Bing Gao ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Directional Solidification ◽  
Nitrogen Concentration ◽  
Solidification Process ◽  
Multicrystalline Silicon ◽  
Molten Silicon ◽  
Directional Solidification Process ◽  
Silicon Based ◽  
Crystal Interface ◽  
Nitride Precipitation

The content and uniformity of impurities and precipitates have an important role in the efficiency of solar cells made of multicrystalline silicon. We developed a transient global model of heat and mass transfer for directional solidification for multicrystalline silicon and a dynamic model of SiC particles and silicon nitride precipitation in molten silicon based phase diagrams. Computations were carried out to clarify the distributions of carbon, nitrogen and oxygen based on segregation and the particle formation in molten silicon during a directional solidification process. It was shown that the content of SiC precipitated in solidified ingots increases as a function of the fraction solidified. It was also clarified from the results that Si2N2O was first formed near the melt-crystal interface, since oxygen concentration in the melt decreases and nitrogen concentration in the melt increases with solidification of the molten silicon. Si3N4 was formed after Si2N2O had been formed.

scholarly journals Influence of Crucible Thermal Conductivity on Crystal Growth in an Industrial Directional Solidification Process for Silicon Ingots

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Zaoyang Li ◽  
Lijun Liu ◽  
Yunfeng Zhang ◽  
Genshu Zhou
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Crystal Growth ◽  
Directional Solidification ◽  
Silicon Crystal ◽  
Solidification Process ◽  
Interface Shape ◽  
Directional Solidification Process ◽  
Reasonable Range ◽  
Crystal Interface

We carried out transient global simulations of heating, melting, growing, annealing, and cooling stages for an industrial directional solidification (DS) process for silicon ingots. The crucible thermal conductivity is varied in a reasonable range to investigate its influence on the global heat transfer and silicon crystal growth. It is found that the crucible plays an important role in heat transfer, and therefore its thermal conductivity can influence the crystal growth significantly in the entire DS process. Increasing the crucible thermal conductivity can shorten the time for melting of silicon feedstock and growing of silicon crystal significantly, and therefore large thermal conductivity is helpful in saving both production time and power energy. However, the high temperature gradient in the silicon ingots and the locally concave melt-crystal interface shape for large crucible thermal conductivity indicate that high thermal stress and dislocation propagation are likely to occur during both growing and annealing stages. Based on the numerical simulations, some discussions on designing and choosing the crucible thermal conductivity are presented.

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