Numerical analysis of the influence of tilt of crucibles on interface shape and fields of temperature and velocity in the unidirectional solidification process

Miyazawa, Hiroaki; Liu, Lijun; Hisamatsu, Sho; Kakimoto, Koichi

doi:10.1016/j.jcrysgro.2007.12.021

Cited by 43 publications

(34 citation statements)

References 12 publications

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“…(5) and (6). To represent the level of thermal stress components, the von Mises stress, s von , is introduced as…”

Section: Simulation Model and Methodsmentioning

confidence: 99%

“…Many studies on optimization of a unidirectional process of crystalline silicon for solar cells have been carried out [3][4][5][6][7][8][9][10][11]. Liu calculated time-dependent distribution of iron and temperature [3], carbon concentration and SiC particle precipitation [4] in a silicon ingot.…”

Section: Introductionmentioning

confidence: 99%

“…Liu calculated time-dependent distribution of iron and temperature [3], carbon concentration and SiC particle precipitation [4] in a silicon ingot. The melt-solid interface shapes of a silicon ingot in unidirectional solidification and casting processes were studied by Vizman et al [5] and Miyazawa et al [6,7]. The relative movement of various parts of furnace was considered in a global 3D time-dependent numerical simulation by Delannoy et al [8].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study on thermal stress in a silicon ingot during a unidirectional solidification process

Chen

Nakano

Liu

et al. 2008

Journal of Crystal Growth

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“…(5) and (6). To represent the level of thermal stress components, the von Mises stress, s von , is introduced as…”

Section: Simulation Model and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study on thermal stress in a silicon ingot during a unidirectional solidification process

Chen

Nakano

Liu

et al. 2008

Journal of Crystal Growth

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“…[16][17][18][19] The graphite components, which are the main sources of carbon elements in grown crystal, include heat shields, heaters, and the crucible pedestal. The basic processes of carbon and oxygen incorporation into a crystal from the graphite components are shown in Figure 1.…”

Section: Mechanism Of Carbon and Oxygen Incorporationmentioning

confidence: 99%

Reducing impurities of multicrystalline silicon in a unidirectional solidification furnace for solar cells

Gao

Nakano

Kakimoto

2011

JOM

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How would you……describe the overall significance of this paper? This paper proposed some methods to reduce the impurities of carbon and oxygen during the production of multicrystalline silicon. Therefore, high-quality and high-efficiency multicrystalline silicon can be obtained by the present solutions.…describe this work to a materials science and engineering professional with no experience in your technical specialty? We theoretically analyzed the incorporation mechanism of impurities of carbon and oxygen, and proposed to use a crucible cover to effectively reduce the carbon and oxygen impurities. Impurities can be further reduced if a reaction between the crucible and the graphite susceptor is prohibited.…describe this work to a layperson? Multicrystalline silicon has now become the main material in the photovoltaic market because of its low production cost and because of the relative high conversion efficiency of solar cells made from this material. The impurities of carbon and oxygen can markedly damage the quality and conversion efficiency of multicrystalline silicon. This paper mainly deals with the purification of carbon and oxygen impurities during production.Multicrystalline silicon has now become the main material in the photovoltaic market because of its low production cost and the relative high conversion efficiency of solar cells made from this material. Effective control of carbon and oxygen impurities in the crystal is required for the production of a high-quality component. In order to reduce impurity levels in a unidirectional solidification furnace, it is proposed to add a crucible cover to the casting process. Results from numerical simulations indicate a marked reduction of carbon impurity in a multicrystalline silicon ingot. The effect of crucible cover material on impurities in multicrystalline silicon was also investigated. These results show that the carbon concentration within the silicon ingot can be reduced by 10 times if the cover is made from carbon and by 1,000 times if the cover is made from tungsten. These results show that an effective and economical method for designing a cover is to use carbon and deposit a thin layer of tungsten on it. Experimental tests have also been carried out by placing a tungsten cover above the crucible. Results indicated that the carbon impurity has significantly decreased; however, the measured carbon concentration in the crystal is larger than the theoretically predicted value, despite the use of a crucible cover. A theoretical analysis has shown that this difference is due to a reaction between the crucible and the graphite susceptor. Furthermore, global simulations have shown that this reaction has a marked effect on carbon and oxygen impurities. When the carbon activity on the surface of the graphite susceptor increases, both oxygen and carbon impurities in crystal increase rapidly. Therefore, the production of high-purity multicrystalline silicon can be improved by designing a crucible cover with a thin layer of tungsten on it and by setting a fr...

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“…The developed simulator has been used successfully in quantitatively predicting the 3D features of a crystal growth. It has also been applied to a variety of crystal growth processes, such as solution growth for GaN [12,13], the PVT method for SiC [14,15], CZ growth, and DS processes for Si crystals [10,11,[16][17][18][19][20][21][22]. To improve the efficiency and accuracy of the global simulation, we also develop a structured/unstructured combined mesh scheme.…”

Section: Introductionmentioning

confidence: 99%

Computer modeling of crystal growth of silicon for solar cells

Liu

et al. 2011

Front. Energy

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A computer simulator with a global model of heat transfer during crystal growth of Si for solar cells is developed. The convective, conductive, and radiative heat transfers in the furnace are solved together in a coupled manner using the finite volume method. A three-dimensional (3D) global heat transfer model with 3D features is especially made suitable for any crystal growth, while the requirement for computer resources is kept permissible for engineering applications. A structured/unstructured combined mesh scheme is proposed to improve the efficiency and accuracy of the simulation. A dynamic model for the melt-crystal (mc) interface is developed to predict the phase interface behavior in a crystal growth process. Dynamic models for impurities and precipitates are also incorporated into the simulator.Applications of the computer simulator to Czochralski (CZ) growth processes and directional solidification processes of Si crystals for solar cells are introduced. Some typical results, including the turbulent melt flow in a large-scale crucible of a CZ-Si process, the dynamic behaviors of the mc interface, and the transport and distributions of impurities and precipitates, such as oxygen, carbon, and SiC particles, are presented and discussed. The findings show the importance of computer modeling as an effective tool in the analysis and improvement of crystal growth processes and furnace designs for solar Si material.

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Numerical analysis of the influence of tilt of crucibles on interface shape and fields of temperature and velocity in the unidirectional solidification process

Cited by 43 publications

References 12 publications

Study on thermal stress in a silicon ingot during a unidirectional solidification process

Study on thermal stress in a silicon ingot during a unidirectional solidification process

Reducing impurities of multicrystalline silicon in a unidirectional solidification furnace for solar cells

Computer modeling of crystal growth of silicon for solar cells

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