在不同硼擴散源擴散過程中，經常會生成硼矽合金層(Boron rich layer, BRL)在硼矽玻璃(Borosilicate glass, BSG)與射極之間，其具有良好的去疵效應(Gettering effect)，但對於太陽能電池元件來說，BRL會造成嚴重複合使得反向飽和電流密度增加，且其存在會導致接觸電阻上升，因此會透過低溫氧化或是蝕刻的方式去除。 本研究利用旋轉塗佈之擴散源擴散形成N型雙面受光型太陽能電池之射極，觀察以不同濃度之擴散源形成的BRL情形，藉以探討其生成現象，並使用低溫氧化方式去除BRL，去除後反向飽和電流密度(Inverse saturation current density)由1.2x10-11 A/cm2降至4.5x10-13 A/cm2，接觸電阻(Contact resistivity)則從11.06 mΩ-cm2降至3.97 mΩ-cm2。 為了探討不同BRL厚度的變化會如何反應在太陽能電池元件，我們將不同氧化條件製作成雙面受光型太陽能電池，發現隨著BRL變薄，內部量子效率光譜響應圖中短波長的部份有明顯的提升，而在太陽能電池電性部份，隨著氧化時間的增長，短路電流密度(Jsc)提升4.2 mA/cm2；填充因子(FF)提升6.9%；轉換效率(η)則提升了1.7%。 ;Most current B diffusion processes used to fabricate n-type solar cell result in the formation of BRL which is located between the borosilicate glass (BSG) and emitter region. The formation of BRL is effective at gettering, but it’s harmful to silicon solar cell performance. The recombination centers in the BRL cause saturation current density degradation, and as the thickness of BRL increases, the contact resistance value increases. Low temperature oxidation and chemical etching are often used to remove the BRL. In this work, we used boron acid as spin-on dopants to form the emitter of n-type bifacial silicon solar cells. We observed the formation of BRL by different concentration boron acid and investigated the influence of removal of the BRL by low temperature oxidation on inverse saturation current density and contact resistivity. We obtained that removing the BRL reduce inverse saturation current density from 1.2x10-11 A/cm2 to 4.5x10-13 A/cm2. In addition, the contact resistance value decreases from 11.06 mΩ-cm2 to 3.97 mΩ-cm2. In order to explore the effects of gradual removal of the BRL in the finished cell, we applied different oxidation conditions to bifacial solar cell. We observed that when the thickness of the BRL decreases, the IQE response increases in the short wavelength. As for the cell performance, it shown that the optimum oxidation condition raised the saturation current density by 4.2 mA/cm2; fill factor by 6.9%; the cell efficiency by 1.7%.
