【摘要】：太陽能是一種重要的綠色可再生能源,并且在二十一世紀(jì)前半期成為最重要的基礎(chǔ)能源之一。目前為止,在光伏發(fā)電中晶硅類太陽能電池占整個光伏市場的90%以上,在晶硅類材料中,傳統(tǒng)直拉單晶硅材料中雜質(zhì)和缺陷的含量低且其太陽能電池轉(zhuǎn)換效率高,但生產(chǎn)成本也較高；鑄造多晶硅生產(chǎn)成本低,但其內(nèi)部存在較多的晶界、位錯和雜質(zhì),嚴(yán)重影響其太陽電池的轉(zhuǎn)換效率。鑄造準(zhǔn)單晶硅結(jié)合了直拉單晶硅與鑄造多晶硅的優(yōu)勢,其生產(chǎn)成本低且轉(zhuǎn)化效率高,它的出現(xiàn)對光伏產(chǎn)業(yè)具有重要意義。圍繞低成本高效率太陽能電池晶硅材料,本文采用專業(yè)晶體生長數(shù)值模擬軟件(CGsim)對太陽能級鑄造準(zhǔn)單晶硅生長過程中感應(yīng)加熱和電阻加熱兩種加熱條件下進(jìn)行功耗對比,并對感應(yīng)線圈高度、感應(yīng)線圈頻率及拉錠速度對熔體流動行為、固液界面及晶體氧含量進(jìn)行了系統(tǒng)的數(shù)值模擬,并獲得結(jié)果如下：(1)運(yùn)用感應(yīng)和電阻兩種加熱方式獲得了大致相同的熔體流動狀態(tài)。感應(yīng)加熱方式下熔體內(nèi)部的溫度更加均勻且有效地降低熔體內(nèi)的溫度梯度,有利于晶體生長。(2)熔體中電磁力是熔體流動的驅(qū)動力之一,并且感應(yīng)線圈高度與熔體高度的比值(k)對熔體內(nèi)電磁力的大小和分布具有很大的影響,當(dāng)k值為1.2時,熔體內(nèi)形成一個上下貫通的渦流,有利于雜質(zhì)的揮發(fā)。同時,當(dāng)感應(yīng)線圈頻率在3000 Hz-5000 Hz范圍時,熔體對流強(qiáng)度較低,可以增加坩堝-熔體邊界層的厚度,降低熔體中的氧含量。(3)隨著拉錠速度的增大,固液界面曲率逐漸加大,增加了鑄錠邊緣區(qū)域多晶的形成幾率；另一方面,熔體溫度逐漸降低,導(dǎo)致晶體氧含量會逐漸減少；同時,拉錠速度大于10 mm/h時,固液界面處V/Gn值均大于臨界值。最終,最佳的鑄造準(zhǔn)單晶硅拉錠速度為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..
【學(xué)位授予單位】：寧夏大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TM914.4;TN304.12

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相關(guān)博士學(xué)位論文 前1條

1 張興國;電磁鑄造技術(shù)的研究[D];大連理工大學(xué);2001年

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本文編號：2402853