出炉温度对定向凝固硅锭质量影响的模拟研究
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摘要
多晶硅是当前太阳能电池的主要材料之一,其定向凝固生产中出炉温度的选择直接影响硅锭质量和能耗。本文运用有限元方法对定向凝固多晶硅锭出炉冷却过程进行了模拟仿真。结果发现:多晶硅锭的最佳出炉温度应在600 K到700 K的温度范围。高于该温度范围,硅锭中的位错密度有微小的增大,硅锭质量下降,最大拉应力的峰值在15 MPa以上,硅锭甚至有开裂风险。低于该温度范围,硅锭中的应力和位错密度在出炉冷却过程中基本保持恒定,降低出炉温度只是增加了时间和能量的浪费。
polycrystalline silicon is one of the main materials of solar cells. The choice of firing temperature in directionally solidified production directly affects the quality and energy consumption of silicon ingot. In this paper, the cooling process of directional solidification polysilicon ingot is simulated by finite element method. It is found that the optimum temperature of the polysilicon ingot should be in the temperature range from 600 K to 700 K. Higher than the temperature range, the dislocation density in the silicon ingot has a slight increase, the quality of the silicon ingot decreases, the peak tensile stress is above 15 MPa, and the silicon ingot even has the risk of cracking. Under the temperature range, the stress and dislocation density in the silicon ingot are basically kept constant during the cooling process, and reducing the temperature of the furnace only increases the waste of time and energy.
polycrystalline silicon is one of the main materials of solar cells. The choice of firing temperature in directionally solidified production directly affects the quality and energy consumption of silicon ingot. In this paper, the cooling process of directional solidification polysilicon ingot is simulated by finite element method. It is found that the optimum temperature of the polysilicon ingot should be in the temperature range from 600 K to 700 K. Higher than the temperature range, the dislocation density in the silicon ingot has a slight increase, the quality of the silicon ingot decreases, the peak tensile stress is above 15 MPa, and the silicon ingot even has the risk of cracking. Under the temperature range, the stress and dislocation density in the silicon ingot are basically kept constant during the cooling process, and reducing the temperature of the furnace only increases the waste of time and energy.
引文
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[5]Zhou Naigen,Lin Maohua,Wan Meiqian,Zhou Lang.Lowering Dislocation Density of Directionally Grown Multicrystalline Silicon Ingots for Solar Cells by Simplifying Their PostSolidification Processes-A Simulation Approach.Journal of Thermal Stresses,38,146-155,2015.
[6]Alexander H,Haasen P.Dislocations and Plastic Flow in the Diamond Structure[J].1969,Volume 22:27-158.
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[2]Wu B,Stoddard N,Ma R,et al.Bulk multicrystalline silicon growth for photovoltaic(PV)application[J].Journal of Crystal Growth,2008,310(7):2178-2184.
[3]Yeh K M,Hseih C K,Hsu W C,et al.High–quality multi–crystalline silicon growth for solar cells by grain–controlled directional solidification[J].Progress in Photovoltaics:Research and Applications,2010,18(4):265-271.
[4]Chen X J,Nakano S,Kakimoto K.3D numerical analysis of the influence of material property of a crucible on stress and dislocation in multicrystalline silicon for solar cells[J].Journal of Crystal Growth,2011,318(1):259-264.
[5]Zhou Naigen,Lin Maohua,Wan Meiqian,Zhou Lang.Lowering Dislocation Density of Directionally Grown Multicrystalline Silicon Ingots for Solar Cells by Simplifying Their PostSolidification Processes-A Simulation Approach.Journal of Thermal Stresses,38,146-155,2015.
[6]Alexander H,Haasen P.Dislocations and Plastic Flow in the Diamond Structure[J].1969,Volume 22:27-158.
[7]Maroudas D,Brown R A.On the prediction of dislocation formation in semiconductor crystals grown from the melt:analysis of the haasen model for plastic deformation dynamics[J].Journal of crystal growth,1991,108(1):399-415.