Excellent surface passivation of heavily doped p⁺ silicon by low-temperature plasma-deposited SiOb>xb>/SiNb>yb> dielectric stacks with optimised antireflective performance for solar cell application

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• 作者：Shubham Duttagupta ; Fa-Jun Ma ; Bram Hoex ; Armin G. Aberle
• 关键词：Surface passivation ; Crystalline silicon ; Boron doped p+ emitters ; Plasma-enhanced chemical vapor deposition ; Silicon oxide/Silicon nitride dielectric stacks
• 刊名：Solar Energy Materials and Solar Cells
• 出版年：January, 2014
• 年：2014
• 卷：120
• 期：part_PA
• 页码：204-208
• 全文大小：552 K

文摘

The passivation of p⁺ Si surfaces is challenging due to the fact that most passivation films have an intrinsically high positive fixed charge. In this work we show experimentally that low-temperature plasma-enhanced chemical vapor deposited SiOb>xb>/SiNb>yb> stacks with a low positive fixed charge density (+10¹¹ cm^鈭?) and very low interface defect density (~3脳10¹⁰ eV^鈭? cm^鈭?) as measured by contactless corona-voltage measurements can effectively passivate p⁺ surfaces resulting in emitter saturation current density (Jb>0eb>) values of 25 and 45 fA/cm² on planar and textured 75 惟/sq p⁺ silicon after industrial firing with a set-temperature of ~800 掳C, respectively. Based on contactless corona-voltage measurements and advanced device simulations, we explain the mechanism of surface passivation by PECVD SiOb>xb>/SiNb>yb> dielectric stack to be completely dominated by chemical passivation rather than field-effect passivation. Furthermore, from advanced device simulations we illustrate the role of fixed charge in surface passivation and in the extraction of fundamental surface recombination velocity parameter for p⁺ silicon surfaces. The fundamental surface recombination velocity parameter for electrons is determined to be about 400 cm/s at these c-Si/SiOb>xb> interfaces. With excellent optical and passivation properties, SiOb>xb>/SiNb>yb> dielectric stacks are suitable for high-efficiency and cost-effective industrial n-type silicon wafer solar cells.