碱性含氟液对太阳电池用单晶硅的腐蚀机理研究
发布时间：2019-03-16 12:46
【摘要】：太阳电池的发展至今有几十年了,晶体硅电池一直都是其市场主流,而高效率、低成本是其发展方向。腐蚀技术(即表面织构)是提高晶体硅电池转换效率的重要手段,但诸如金字塔的初始形成机制和腐蚀各向异性等问题仍未得到很好的解决。为了进一步了解腐蚀机理,本论文提出了NaOH/NH4F和NaOH/NH4F/Na2CO3两种腐蚀体系,与纯NaOH溶液进行对比分析研究。通过对表形貌、腐蚀速率和拉曼光谱等实验结果的分析研究,提出了腐蚀-聚合机理及其模型,解释了腐蚀过程中表形貌、腐蚀速率的变化以及其它一些腐蚀体系中出现的实验现象。 纯NaOH溶液腐蚀所得的硅表面为金字塔结构,反射率最低。加入NH4F后,硅表面主要为较短小的山丘状小丘覆盖,反射率较高,一般为15-16%,腐蚀速率则明显降低且完全由它的浓度控制,OH-离子的影响非常微弱。再加入Na2CO3,表面小丘为长长的山链状,反射率比较接近纯NaOH溶液腐蚀(本文实验所得的最低值为12.85%),腐蚀速率比NaOH/NH4F体系的略低。为了进一步的深入研究,实验测定了三种腐蚀体系的拉曼光谱,结果发现这三种腐蚀体系和硅片表面硅酸盐的聚合都有明显变化,其聚合程度都是NaOH/NH4F/Na2CO3体系强于NaOH/NH4F体系,NaOH/NH4F体系又强于纯NaOH溶液,并且都没有Si-F键存在。 基于这些实验结果,本文提出了腐蚀-聚合理论。这一理论认为硅腐蚀后的表形貌受产物硅酸盐聚合的影响,聚合所产生的氧化硅是金字塔、小山丘和山链形成的微掩膜。在碱性含氟溶液中,硅腐蚀的中间产物为SiHxFy(OH)z,它并不稳定,最终会变为硅酸盐。硅酸盐的聚合方式有三种：path1(亲核脱质子硅醇三Si-O-与中性硅酸盐物种的反应)、path2(Si-OH群的桥接反应)和path3(Si-F直接与Si-OH反应)。path1和path2聚合所形成的产物聚合度低,path3不仅能在硅酸盐浓度低时发生而且产物的聚合度还比较高。纯NaOH溶液聚合按path1和path2进行,所形成的微掩膜尺寸最小,表面小丘为金字塔。NaOH/NH4F体系三种聚合方式都发生,所形成的微掩膜尺寸较大,硅表面为条状小山丘覆盖。C032-离子虽也能促进聚合,但加入纯NaOH溶液只能增加金字塔的密度,而加入NaOH/NH4F体系与F-离子共同作用却能提高聚合度,使条状小山丘变成长长的山链。根据腐蚀过程中硅表面反应物H2O和OH-离子的浓度变化以及氧化硅掩膜的形成,腐蚀-聚合理论解释了本文三种腐蚀体系形成的表形貌差异。再结合腐蚀过程中表形貌引起的腐蚀速率变化,它还能解释一些其它实验现象,如金字塔崩顶和各种添加剂的影响等。 基于腐蚀-聚合理论,本文建立了腐蚀-聚合原子模型。这一模型不仅解释了多种形状的小丘形成,还解释了它们形成的难易程度。金字塔是以一个氧化硅顶点为掩膜形成的小丘,其氧化物聚合度最低,最易于形成。(111)条状小丘以氧化硅密度最高、最不易形成的多个氧化硅顶点为掩膜,所以(111)条状小丘很难形成。六面小丘以氧化硅密度相对(111)条状小丘较低的多个顶点为掩膜,相对容易形成,本文NaOH/NH4F体系腐蚀出的小丘就近似这种形状。此外,氧化硅掩膜若中途形成在金字塔的(111)面上则会形成(110)面。若(111)面上氧化硅形成得很少,(110)面小得可忽略或是氧化硅形成在金字塔的棱上,那么金字塔(111)面的倾角变小,金字塔发生延展,这解释了金字塔的倾角小于理论值54.735°；若(111)面上氧化硅形成得很多,(110)面不可忽略,那么金字塔变成八面锥,这解释了八面锥的出现。 腐蚀-聚合理论及其模型成功解释了金字塔初始形成以及腐蚀过程中表形貌变化、腐蚀速率变化等实验现象,成为Si表面腐蚀技术的理论组成部分,为高效率、低成本硅太阳电池的研究开发奠定了较好的理论基础。
[Abstract]:The solar cell has been developed for several decades, and the crystalline silicon cell has been the mainstream of its market, and its high efficiency and low cost are its development direction. Corrosion technology (i.e., surface texture) is an important means to improve the conversion efficiency of crystalline silicon cells, but problems such as the initial formation mechanism of the pyramid and the corrosion anisotropy are still not well solved. In order to further understand the corrosion mechanism, the two kinds of corrosion system of NaOH/ NH4F and NaOH/ NH4F/ Na2CO3 were put forward, and compared with the pure NaOH solution. The corrosion-polymerization mechanism and the model of the corrosion-polymerization mechanism are put forward by the analysis of the experimental results such as the morphology, the corrosion rate and the Raman spectrum of the table. The appearance of the table, the change of the corrosion rate and the experimental phenomena in some other corrosion systems are explained. the surface of the silicon obtained by the corrosion of the pure NaOH solution is a pyramid structure, and the reflectivity is the most After the addition of the NH4F, the surface of the silicon is mainly covered with a small hill-shaped hillock, the reflectivity is high, the average is 15-16%, the corrosion rate is obviously reduced and the concentration is controlled completely, and the effect of the OH-ions is very small. Weak. Add Na2CO3, the surface hillock is a long mountain chain, the reflectance is close to the pure NaOH solution corrosion (the lowest value in the experiment is 12.85%), the corrosion rate is lower than that of the NaOH/ NH4F system. In order to further study, the Raman spectra of the three kinds of corrosion systems have been determined. The results show that the polymerization of the three kinds of corrosion system and the surface silicate of the silicon wafer is obviously changed. The degree of polymerization is the NaOH/ NH4F/ Na2CO3 system which is stronger than the NaOH/ NH4F system, and the NaOH/ NH4F system is stronger than that of the pure NaOH solution. Liquid, and no Si-F bond In this paper, based on the results of these experiments, the corrosion-poly was proposed. The theory is that the surface morphology after silicon corrosion is influenced by the polymerization of the product silicate, and the silicon oxide produced by the polymerization is formed by the pyramid, the small hill and the mountain chain. The micro-mask. In the basic fluorine-containing solution, the intermediate product of silicon corrosion is SiHxFy (OH) z, which is not stable and will eventually become There are three ways of polymerization of silicate and silicate: path1 (the reaction of the nucleophilic deprotonated triSi-O-with the neutral silicate species), the path2 (the bridging reaction of the Si-OH group) and the path3 (Si-F are directly related to Si-OH). the degree of polymerization of the product formed by the polymerization of the path1 and the path2 is low, and the path3 can occur not only when the concentration of the silicate is low, but also the degree of polymerization of the product the solution polymerization of pure naoh is carried out according to the path1 and the path2, the size of the formed micro-mask is the smallest, and the surface hillock is There are three kinds of polymerization modes of the pyramid. NaOH/ NH4F system, the size of the micro-mask is large, and the silicon surface is a strip-shaped hill. The CC032-ion can also promote the polymerization, but the addition of the pure NaOH solution can only increase the density of the pyramid, but the addition of the NaOH/ NH4F system and the F-ion can improve the degree of polymerization, so that the strip-shaped small hill becomes long. According to the change of the concentration of the reactant H2O and OH-ions in the silicon surface during the etching process and the formation of the silicon oxide mask, the corrosion-polymerization theory explains the form of the three kinds of corrosion systems in this paper. It can also explain some other experimental phenomena, such as pyramid collapse and various additives. The corrosion-polymerization theory is established in this paper based on the theory of corrosion-polymerization. The model not only explains the formation of a variety of shapes, but also explains their formation. The pyramid is a small hill formed by using a silicon oxide vertex as a mask, the oxide degree of polymerization is the lowest, and (111) the strip-shaped hillock is the highest in the density of the silicon oxide, and the plurality of silicon oxide vertices which are not easily formed are used as a mask, so (111) the strip-shaped small hills are small in strip shape, The hillock is hard to form. The small hillock is relatively easy to form with a plurality of apexes with a low silicon oxide density (111), which is relatively easy to form, and the small hillock, which is corroded by the NaOH/ NH4F system, is nearby. In addition, if the silicon oxide mask is formed on the (111) surface of the pyramid in the middle, 110) If (111) the silicon oxide on the (111) surface is formed very little, (110) the surface is small, or the silicon oxide is formed on the edge of the pyramid, the inclination of the pyramid (111) surface becomes smaller and the pyramid is extended, which explains that the inclination angle of the pyramid is less than the theoretical value 54 . The corrosion-polymerization theory and its model explain the experimental phenomena of the initial formation of the pyramid and the change of the appearance of the table in the process of corrosion and the change of the corrosion rate. The research and development of high-efficiency and low-cost silicon solar cell have laid the foundation for the research and development of high-efficiency
【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM914.4
本文编号：2441386
[Abstract]:The solar cell has been developed for several decades, and the crystalline silicon cell has been the mainstream of its market, and its high efficiency and low cost are its development direction. Corrosion technology (i.e., surface texture) is an important means to improve the conversion efficiency of crystalline silicon cells, but problems such as the initial formation mechanism of the pyramid and the corrosion anisotropy are still not well solved. In order to further understand the corrosion mechanism, the two kinds of corrosion system of NaOH/ NH4F and NaOH/ NH4F/ Na2CO3 were put forward, and compared with the pure NaOH solution. The corrosion-polymerization mechanism and the model of the corrosion-polymerization mechanism are put forward by the analysis of the experimental results such as the morphology, the corrosion rate and the Raman spectrum of the table. The appearance of the table, the change of the corrosion rate and the experimental phenomena in some other corrosion systems are explained. the surface of the silicon obtained by the corrosion of the pure NaOH solution is a pyramid structure, and the reflectivity is the most After the addition of the NH4F, the surface of the silicon is mainly covered with a small hill-shaped hillock, the reflectivity is high, the average is 15-16%, the corrosion rate is obviously reduced and the concentration is controlled completely, and the effect of the OH-ions is very small. Weak. Add Na2CO3, the surface hillock is a long mountain chain, the reflectance is close to the pure NaOH solution corrosion (the lowest value in the experiment is 12.85%), the corrosion rate is lower than that of the NaOH/ NH4F system. In order to further study, the Raman spectra of the three kinds of corrosion systems have been determined. The results show that the polymerization of the three kinds of corrosion system and the surface silicate of the silicon wafer is obviously changed. The degree of polymerization is the NaOH/ NH4F/ Na2CO3 system which is stronger than the NaOH/ NH4F system, and the NaOH/ NH4F system is stronger than that of the pure NaOH solution. Liquid, and no Si-F bond In this paper, based on the results of these experiments, the corrosion-poly was proposed. The theory is that the surface morphology after silicon corrosion is influenced by the polymerization of the product silicate, and the silicon oxide produced by the polymerization is formed by the pyramid, the small hill and the mountain chain. The micro-mask. In the basic fluorine-containing solution, the intermediate product of silicon corrosion is SiHxFy (OH) z, which is not stable and will eventually become There are three ways of polymerization of silicate and silicate: path1 (the reaction of the nucleophilic deprotonated triSi-O-with the neutral silicate species), the path2 (the bridging reaction of the Si-OH group) and the path3 (Si-F are directly related to Si-OH). the degree of polymerization of the product formed by the polymerization of the path1 and the path2 is low, and the path3 can occur not only when the concentration of the silicate is low, but also the degree of polymerization of the product the solution polymerization of pure naoh is carried out according to the path1 and the path2, the size of the formed micro-mask is the smallest, and the surface hillock is There are three kinds of polymerization modes of the pyramid. NaOH/ NH4F system, the size of the micro-mask is large, and the silicon surface is a strip-shaped hill. The CC032-ion can also promote the polymerization, but the addition of the pure NaOH solution can only increase the density of the pyramid, but the addition of the NaOH/ NH4F system and the F-ion can improve the degree of polymerization, so that the strip-shaped small hill becomes long. According to the change of the concentration of the reactant H2O and OH-ions in the silicon surface during the etching process and the formation of the silicon oxide mask, the corrosion-polymerization theory explains the form of the three kinds of corrosion systems in this paper. It can also explain some other experimental phenomena, such as pyramid collapse and various additives. The corrosion-polymerization theory is established in this paper based on the theory of corrosion-polymerization. The model not only explains the formation of a variety of shapes, but also explains their formation. The pyramid is a small hill formed by using a silicon oxide vertex as a mask, the oxide degree of polymerization is the lowest, and (111) the strip-shaped hillock is the highest in the density of the silicon oxide, and the plurality of silicon oxide vertices which are not easily formed are used as a mask, so (111) the strip-shaped small hills are small in strip shape, The hillock is hard to form. The small hillock is relatively easy to form with a plurality of apexes with a low silicon oxide density (111), which is relatively easy to form, and the small hillock, which is corroded by the NaOH/ NH4F system, is nearby. In addition, if the silicon oxide mask is formed on the (111) surface of the pyramid in the middle, 110) If (111) the silicon oxide on the (111) surface is formed very little, (110) the surface is small, or the silicon oxide is formed on the edge of the pyramid, the inclination of the pyramid (111) surface becomes smaller and the pyramid is extended, which explains that the inclination angle of the pyramid is less than the theoretical value 54 . The corrosion-polymerization theory and its model explain the experimental phenomena of the initial formation of the pyramid and the change of the appearance of the table in the process of corrosion and the change of the corrosion rate. The research and development of high-efficiency and low-cost silicon solar cell have laid the foundation for the research and development of high-efficiency
【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM914.4
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