在本項研究中，為了降低製作局部背表面電場成本，我們提出以簡單新穎的製程方式製作局部背表面電場運用在結晶矽太陽能電池中。背表面鈍化層是使用SiOxNy和SiNx雙層堆疊結構，利用高分子薄膜製作出微米孔洞圖形遮罩，並製備局部背表面鈍化層，運用於電池中，製備出隨機局部鋁背表面電場 (Random local Al back surface field)太陽能電池，探討其不同背表面接觸面積之少數載子生命週期變化和太陽能電池光電轉換特性。 本研究將針對不同孔洞接觸面積變化探討對於電池效率之影響，且電極接觸形狀與鋁背表面電場厚度有強烈的關係，後續並探討剝除局部介電層和接觸面積之關係。本實驗顯示，局部背表面電場能有效的改善載子生命週期，當孔洞接觸面積愈多時，表面鈍化層移除則愈多，有效少數載子生命週期則愈低，當孔洞接觸面積達到百分之四十以上，其有效載子生命週期與整面表面電場幾乎相同。其電池背表面孔洞接觸面積為7.3 %時有最佳光電轉換效率之表現，電池面積為10 mm × 10 mm，製備於p-type單晶矽基板轉換效率可達到13.43 %，比較背面未鈍化，整面背表面電場參考樣品中轉換效率為12.81 %，可看出其光電轉換效率有顯卓的提升。 本研究中，在最佳化隨機鋁局部背表面電場比較整面背表面電場，可觀察出明顯的改善Voc和Jsc，分別提升6.8 mV和2.22 mA，此提升是因為良好背表面內反射和背表面鈍化產生之結果。 ;In this work, in order to reduction cost of local back surface field, we propose a simple and novel process was developed for fabrication of local Al back surface field (BSF) for crystalline Si solar cells. Where a stack of SixONy and SiNx is used as rear surface passivation layer containing holes. Random local Al BSF solar cells with microhole patterned dielectric layers as rear surface passivation have been prepared. A detailed investigation of the effect of local holes contact area on the conversion efficiency of the PERC cells was performed. The effect of rear contact formation on cell efficiency was studied as a function of contact area, hence the metallization fraction. Contact shape and the thickness of Al-BSF layer were found to be heavily dependent on the etch ablation pattern and contact area. When the holes area fraction was higher, the fraction of the passivation film removed was higher and as a consequence, the effective lifetime was smaller. It is shown that the rear surface passivation could effectively increase the lifetime and the cell with around 7.3 % hole area fraction can have best performance. Conversion efficiency of 13.43% was achieved using 10×10 mm, p-type single crystalline silicon wafers. This is a significant improvement when compared to unpassivated, full area aluminum back surface field solar cells, which exhibit only 12.81 % conversion efficiency on the same wafer type. There is an apparent gain in Jsc and Voc of, respectively, 2.22 mA/cm2 and 6.8 mV for the best random Al BSF cells compared to full Al BSF reference cells, because of better rear internal reflection and rear surface passivation.
