感应加热制备太阳能级铸造准单晶硅生长机理研究
发布时间：2019-01-06 13:30
【摘要】：太阳能是一种重要的绿色可再生能源,并且在二十一世纪前半期成为最重要的基础能源之一。目前为止,在光伏发电中晶硅类太阳能电池占整个光伏市场的90%以上,在晶硅类材料中,传统直拉单晶硅材料中杂质和缺陷的含量低且其太阳能电池转换效率高,但生产成本也较高；铸造多晶硅生产成本低,但其内部存在较多的晶界、位错和杂质,严重影响其太阳电池的转换效率。铸造准单晶硅结合了直拉单晶硅与铸造多晶硅的优势,其生产成本低且转化效率高,它的出现对光伏产业具有重要意义。围绕低成本高效率太阳能电池晶硅材料,本文采用专业晶体生长数值模拟软件(CGsim)对太阳能级铸造准单晶硅生长过程中感应加热和电阻加热两种加热条件下进行功耗对比,并对感应线圈高度、感应线圈频率及拉锭速度对熔体流动行为、固液界面及晶体氧含量进行了系统的数值模拟,并获得结果如下：(1)运用感应和电阻两种加热方式获得了大致相同的熔体流动状态。感应加热方式下熔体内部的温度更加均匀且有效地降低熔体内的温度梯度,有利于晶体生长。(2)熔体中电磁力是熔体流动的驱动力之一,并且感应线圈高度与熔体高度的比值(k)对熔体内电磁力的大小和分布具有很大的影响,当k值为1.2时,熔体内形成一个上下贯通的涡流,有利于杂质的挥发。同时,当感应线圈频率在3000 Hz-5000 Hz范围时,熔体对流强度较低,可以增加坩埚-熔体边界层的厚度,降低熔体中的氧含量。(3)随着拉锭速度的增大,固液界面曲率逐渐加大,增加了铸锭边缘区域多晶的形成几率；另一方面,熔体温度逐渐降低,导致晶体氧含量会逐渐减少；同时,拉锭速度大于10 mm/h时,固液界面处V/Gn值均大于临界值。最终,最佳的铸造准单晶硅拉锭速度为10 mm/h—15 mm/h。
[Abstract]:Solar energy is an important green renewable energy, and it became one of the most important basic energy in the first half of 21 century. Up to now, the crystalline silicon solar cells account for more than 90% of the total photovoltaic market in photovoltaic power generation. In the crystal silicon materials, the content of impurities and defects in the traditional Czochralski silicon materials is low and the conversion efficiency of the solar cells is high. But the production cost is also high; The production cost of casting polysilicon is low, but there are many grain boundaries, dislocations and impurities inside, which seriously affect the conversion efficiency of solar cells. Casting quasicrystal silicon combines the advantages of Czochralski silicon and cast polysilicon, its production cost is low and conversion efficiency is high, its appearance is of great significance to photovoltaic industry. Around the low cost and high efficiency solar cell crystal silicon material, this paper compares the power consumption between induction heating and resistance heating in the growth process of solar grade casting quasicrystalline silicon by using the specialized crystal growth numerical simulation software (CGsim). The influence of induction coil height, induction coil frequency and drawing speed on melt flow behavior, solid-liquid interface and oxygen content of crystal were simulated systematically. The results are as follows: (1) the same melt flow state is obtained by using induction heating and resistance heating. Under induction heating, the temperature inside the melt is more uniform and can effectively reduce the temperature gradient in the melt, which is beneficial to crystal growth. (2) the electromagnetic force in the melt is one of the driving forces of the melt flow. The ratio of induction coil height to melt height (k) has great influence on the size and distribution of electromagnetic force in the melt. When k value is 1. 2, a vortex is formed in the melt, which is favorable to the volatilization of impurities. At the same time, when the frequency of induction coil is in the range of 3000 Hz-5000 Hz, the convection intensity of melt is lower, which can increase the thickness of crucible melt boundary layer and decrease the oxygen content in melt. (3) with the increase of drawing speed, The curvature of solid-liquid interface increases gradually, which increases the probability of polycrystalline formation in the ingot edge. On the other hand, the melt temperature decreases gradually, which leads to the decrease of oxygen content in the crystal, and the V/Gn value at the solid-liquid interface is larger than the critical value when the drawing speed of the ingot is more than 10 mm/h. Finally, the best casting speed of quasicrystal silicon ingot is 10 mm/h-15 mm/h..
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM914.4;TN304.12
本文编号：2402853
[Abstract]:Solar energy is an important green renewable energy, and it became one of the most important basic energy in the first half of 21 century. Up to now, the crystalline silicon solar cells account for more than 90% of the total photovoltaic market in photovoltaic power generation. In the crystal silicon materials, the content of impurities and defects in the traditional Czochralski silicon materials is low and the conversion efficiency of the solar cells is high. But the production cost is also high; The production cost of casting polysilicon is low, but there are many grain boundaries, dislocations and impurities inside, which seriously affect the conversion efficiency of solar cells. Casting quasicrystal silicon combines the advantages of Czochralski silicon and cast polysilicon, its production cost is low and conversion efficiency is high, its appearance is of great significance to photovoltaic industry. Around the low cost and high efficiency solar cell crystal silicon material, this paper compares the power consumption between induction heating and resistance heating in the growth process of solar grade casting quasicrystalline silicon by using the specialized crystal growth numerical simulation software (CGsim). The influence of induction coil height, induction coil frequency and drawing speed on melt flow behavior, solid-liquid interface and oxygen content of crystal were simulated systematically. The results are as follows: (1) the same melt flow state is obtained by using induction heating and resistance heating. Under induction heating, the temperature inside the melt is more uniform and can effectively reduce the temperature gradient in the melt, which is beneficial to crystal growth. (2) the electromagnetic force in the melt is one of the driving forces of the melt flow. The ratio of induction coil height to melt height (k) has great influence on the size and distribution of electromagnetic force in the melt. When k value is 1. 2, a vortex is formed in the melt, which is favorable to the volatilization of impurities. At the same time, when the frequency of induction coil is in the range of 3000 Hz-5000 Hz, the convection intensity of melt is lower, which can increase the thickness of crucible melt boundary layer and decrease the oxygen content in melt. (3) with the increase of drawing speed, The curvature of solid-liquid interface increases gradually, which increases the probability of polycrystalline formation in the ingot edge. On the other hand, the melt temperature decreases gradually, which leads to the decrease of oxygen content in the crystal, and the V/Gn value at the solid-liquid interface is larger than the critical value when the drawing speed of the ingot is more than 10 mm/h. Finally, the best casting speed of quasicrystal silicon ingot is 10 mm/h-15 mm/h..
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM914.4;TN304.12
【参考文献】
相关博士学位论文 前1条
1 张兴国;电磁铸造技术的研究[D];大连理工大学;2001年
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