利用由氯化鋁與矽酸根溶液塗佈與臭氧氧化形成氧化鋁鈍化層與局部接觸結構之單晶矽太陽能電池之研究

Using AlCl₃/SiO₃²⁻ Solution and Ozone Oxidation to Form Aluminum Oxide Passivation Layer on Rear Side of Monocrystalline Silicon Solar Cell

鄭宇倫(Yu-Lun Cheng)

指導教授 ： 王立康

國立清華大學/電機資訊學院/光電工程研究所/碩士(2021年)

摘要

本實驗室致力於改善太陽能電池的鈍化層，近年來太陽能電池又隨著種種議題回到眾人的討論，而在這之中，如何以最低成本製作高效的太陽能電池是一件非常值得探討的議題，而本實驗為製作PERC太陽能電池。我們會以溶液塗佈與臭氧的方式形成鈍化層。使用濕式製程製作來降低成本，並利用臭氧氧化能力極強的特性形成較為緻密的鈍化層。
　　首先，我們使用P型矽基板來製作。我們將會探討氯化鋁與矽酸根溶液塗佈在基板背面形成三氧化二鋁作為鈍化層，在塗佈溶液後，我們會使用臭氧氧化，此後進行退火。我們會找出此溶液最佳的濃度、退火溫度與退火時間。在後續進行完退火後，為了觀察氧化鋁薄膜的特性，使用EDS、TEM量測來看成分的組成以及結構。我們使用最佳的參數為，氯化鋁比水的體積百分濃度100ml:0.5ml，矽酸根的體積百分濃度100ml:1ml，並將0.5ml的矽酸根加入50ml的氯化鋁溶液中，氧化時間20分鐘，退火時間15分鐘，退火溫度為500℃。得出的PERC太陽能電池，其最佳填充因子為75.6%、轉換效率為16.917%，比全面鋁的太陽能電池相比提升了0.522%。

關鍵字

氯化鋁 ； 矽酸根 ； 太陽能電池 ； 臭氧

並列摘要

Our lab is dedicated to finding a cost-effective way of depositing passivation layers for crystalline silicon solar cells. In recent years, solar cell have returned to human’s attention with various issues to be discussed. However, the issue of how to fabricate low cost and high-efficiency solar cells is always an important one. In this experiment, we develop a new passivation layer formula that is used for passivating the back surfaces of PERC solar cells. Our passivation layer is formed by using a wet chemical process and ozone oxidation. In this wet chemical process with post ozone oxidation, an AlOx layer is believed to be formed on the back surfaces of solar cells and good passivation effect is achieved.
　　In this study, p-type single crystalline silicon wafers were used. We discussed about the deposition process of forming Al2O3 films on rear sides of the wafers as passivation layers by using AlCl3/SiO32- solution. After coating the chemical solution, we then used ozone oxidation followed by an annealing process. The best concentration of the chemical solution,annealing temperature and annealing time period were discussed in this study. Measurements with EDS and TEM facilities were used to observe the elemental composition and the film structure. The best process parameters were found as follows. The volume percentage concentration of AlCl3 and water was 100ml:0.5ml; the volume percentage concentration of silicate solution was 100ml:1ml. 0.5ml of the prepared silicate solution is added into 50ml of the prepared AlCl3 solution. After coating the AlCl3/SiO32- solution, we performed 20-minute ozone oxidation, followed by 15-minute annealing at 500℃. The best PERC solar cell fabricated with this type of passivation layer had a fill factor of 75.6% and a conversion efficiency of 16.917%, the latter of which is 0.522% absolute higher than the best Al-BSF solar cell fabricated in the study.

並列關鍵字

AlCl₃ ； SiO₃²⁻ ； solar cell ； O₃

參考文獻

[1]S. Mack, “Silicon surface passivation by thin thermal oxide/PECVD layer stack systems”, IEEE Journal of Photovoltaics, vol. 1, no. 2, pp. 135-145, 2011.

[2]F. Bellenger, “Passivation of Ge ( 100 ) ∕ GeO2 ∕ high-κ gate stacks using thermal oxide treatments”, Journal of the Electrochemical Society , vol. 155, no. 2, pp.33~38, 2008.

[3]P. Saint-Cast, “High-efficiency c-Si solar cells passivated with ALD and PECVD aluminum oxide”, IEEE Electron Device Letters, vol. 31, no. 7, pp. 695-697, 2010.

[4]S. Zhao, Q. Qiao, S. Zhang, J. Ji, Z. Shi, and G. Li, “Rear passivation of commercial multi-crystalline PERC solar cell by PECVD Al2O3”, Applied Surface Science, vol. 290, no. 0169-4332, pp. 66-70,2014.

[5]M. Y. Seo, E. N. Cho, C. E. Kim, P. Moon, and I. Yun, “Characterization of Al2O3 films grown by electron beam evaporator on Si substrates”, 2010 3rd International Nanoelectronics Conference (INEC), pp. 238-239, 2010.