以多孔隙矽吸雜法提昇冶金矽太陽能電池效率

Improving the efficiency of metallurgical silicon solar cells by porous silicon gettering technique

楊正偉(Cheng-Wei Yang)

指導教授 ： 溫武義

中原大學/工學院/電子工程研究所/碩士(2009年)

https://doi.org/10.6840/cycu200901097

摘要

本論文主要是使用定向凝固鑄造技術製成的純化冶金矽作為矽太陽能電池的基板。純化冶金矽為一種相對低成本的材料，它避免了使用電子級多晶矽和單晶矽做為基板所需要昂貴的西門子製程。此材料也許可供應日漸增加的多晶矽原料需求。
但是純化冶金矽仍然含有許多金屬雜質，且鑄造多晶矽中含有大量的晶界和差排，這些缺陷成為捕捉金屬的優先場所，因此，鑄造多晶矽中的金屬常常被捕捉在晶界和差排處。而這些金屬會導致形成一個新的載子複合中心，這對於由少數載子控制的矽太陽能電池來說，對其效率有極大的損害。
本實驗藉由多孔隙矽吸雜技術來吸除不需要的雜質，經由在矽晶片正面蝕刻多空隙矽薄膜，再經由遠紅外線高溫爐高溫處理，此次實驗成功的展示出經由多孔隙矽吸雜的功效。我們得到在元件在短路電流方面相較於未吸雜處理的提升了約一點六毫安培，而在轉換效率方面也提升至百分之十三點一。

關鍵字

多孔隙矽 ； 去疵技術 ； 太陽能電池

並列摘要

In this study, we use upgraded metallurgical silicon (UMG-Si) by directional solidification casting as the starting materal. UMG-Si is a relatively low cost substrate; it avoids the expensive Siemens process during fabrication of electronic grade poly-silicon material from which mono- and multicrystalline silicon materials are manufactured.
The use of UMG-Si substrate is possible to reduce the fabrication cost of Si-based solar cells. However, this material has a localized region of high density of dislocations and metal impurity precipitates, which in turn act as carrier recombination sites and deteriorate the performance of solar cell fabricated thereon.
It may present a solution to the silicon feedstock shortage by purification of UMG-Si. By porous silicon gettering (PSG) technique, undesired impurities can be driven away from UMG-Si wafer by combining the formation of porous silicon (PS) and the following heat treatments. The latter was conducted in an infrared furnace at different temperatures for a constant time duration of 30 min. The gettering technique used in this work is effected by the formation of a PS film at the front side of the UMG-Si wafer. Experimental results showed that when the base material underwent such a gettering process, the short-circuit current and efficiency of the corresponding solar cells fabricated can be improved. So far, an increase of 1.6 mA in the short-circuit current and therefore a relatively high efficiency of 13.1% has been achieved for the specimen performed with the PSG treatment.

並列關鍵字

gettering ； porous silicon ； solar cell

參考文獻

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