非晶矽薄膜鈍化之矽晶太陽能電池

Crystalline Silicon Solar Cells Passivated by Amorphous Silicon Films

王立康(Li-Karn Wang)

《科儀新知》 190期 (2012/10) Pp. 42-47

https://doi.org/10.29662/IT.201210.0006

摘要

非晶矽薄膜鍍製於矽晶太陽能電池之表面，具有鈍化功能。鈍化的原理係非晶矽薄膜中的氫原子在適當溫度下往矽晶基板移動，修補矽晶基板表面的斷鍵而形成Si-H鍵。除此之外，本質非晶矽薄膜與晶體矽間亦形成等效電場，排阻光生電子往介面移動，而降低在介面之電子電洞複合率。本文探討兩種非晶矽薄膜（含氫與不含氫非晶矽）對矽晶太陽能電池特性之影響。與傳統含氫非晶矽的製程機台PECVD對照，LPCVD機台製程不含氫之非晶矽以及多晶矽對矽晶太陽能電池所產生的表面鈍化效果亦可有效提升開路電壓。光學頻譜響應上的短波長及長波長區段也顯示前表面和背表面的表面複合速率減少導致光電流提升。我們一個較早期實驗的結果顯示，使用LPCVD在矽晶片兩面鍍製多晶矽薄膜後，太陽能電池效率從18.1%提升至18.4%。

並列摘要

Hydrogenated amorphous silicon (a-Si) is a material that can passivate crystalline silicon (c-Si) solar cells, when deposited on the surfaces of the cells. The passivation results from the movement of hydrogen atoms residing in the a-Si toward the a-Si/c-Si interface to fix dangling bonds at a proper temperature and to form Si-H bonds. Besides, a field can be built between the a-Si/c-Si interface, repelling photogenerated electrons to combine with holes and henceforth reducing surface recombination rate. In this article, we present two types of a-Si films (hydrogenated and non-hydrogenated) that prove to improve the performance of crystalline silicon solar cells. Hydrogenated a-Si can be grown on the surface of a silicon solar wafer by PECVD, while non-hydrogenated a-Si can be grown by LPCVD, both improving Voc' One of our earlier experiments revealed that the conversion efficiency of a solar cell with LPCVD grown a-Si deposited on two-side surfaces of the cell was enhanced from 18.1% to 18.4%.