Progress in Research and Development of Solar-grade Silicon Preparation by Electron Beam Melting

doi:10.15541/jim20140664

Abstract

Abstract:

Electron beam melting is an effective method to remove volatile impurities in silicon due to its characteristics of high energy density and high vacuum degree, which has huge advantages and wide application prospects in preparation of solar-grade silicon. Currently it has been successfully applied in industry and become one of the key procedures for preparation of solar-grade silicon by metallurgical route. Based on the thermodynamic principle of the volatile impurities removal, the removal efficiency and mechanism are summarized in this paper. According to current problems of this technology combined with our own experience, the emphasis of current research is reviewed from the points of numerical simulation, energy-saving melting technology and coupling with directional solidification technology. The future development direction of this technology is also proposed.

Key words: electron beam melting, solar-grade silicon, volatile impurities, review

CLC Number:

TF134
TF89

TAN Yi, SHI Shuang, JIANG Da-Chuan. Progress in Research and Development of Solar-grade Silicon Preparation by Electron Beam Melting[J]. Journal of Inorganic Materials, 2015, 30(8): 785-792.

Figures/Tables 9

Fig. 1 Volatility coefficients of impurities in silicon as a function of temperature[20]

Fig. 2 Schematic diagram of silicon refining by electron beam melting[21]

Fig. 3 Morphologies of electron beam melted silicon ingot[20](a) Surface; (b) Bottom; (c) Cross section

Fig. 4 Distribution of impurities in electron beam melted silicon ingot[26]

Fig. 5 Rate constant of impurity evaporation from silicon as a function of temperature[15, 28-29, 37]

Fig. 6 Schematic diagram of the migration process of impurity atom during different steps[29]

Fig. 7 The optimum value of melting parameters for 0.5 kg silicon by electron beam melting[42]

Fig. 8 Process of electron beam melting with low power and shadow melten pool[44]

Fig. 9 Directional solidified silicon ingot induced by electron beam[46]

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