出炉温度对定向凝固硅锭质量影响的模拟研究

Simulation study on influence of temperature on directional solidification of silicon ingot quality

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.