堿性含氟液對太陽電池用單晶硅的腐蝕機理研究
發(fā)布時間：2019-03-16 12:46
【摘要】：太陽電池的發(fā)展至今有幾十年了,晶體硅電池一直都是其市場主流,而高效率、低成本是其發(fā)展方向。腐蝕技術(shù)(即表面織構(gòu))是提高晶體硅電池轉(zhuǎn)換效率的重要手段,但諸如金字塔的初始形成機制和腐蝕各向異性等問題仍未得到很好的解決。為了進一步了解腐蝕機理,本論文提出了NaOH/NH4F和NaOH/NH4F/Na2CO3兩種腐蝕體系,與純NaOH溶液進行對比分析研究。通過對表形貌、腐蝕速率和拉曼光譜等實驗結(jié)果的分析研究,提出了腐蝕-聚合機理及其模型,解釋了腐蝕過程中表形貌、腐蝕速率的變化以及其它一些腐蝕體系中出現(xiàn)的實驗現(xiàn)象。 純NaOH溶液腐蝕所得的硅表面為金字塔結(jié)構(gòu),反射率最低。加入NH4F后,硅表面主要為較短小的山丘狀小丘覆蓋,反射率較高,一般為15-16%,腐蝕速率則明顯降低且完全由它的濃度控制,OH-離子的影響非常微弱。再加入Na2CO3,表面小丘為長長的山鏈狀,反射率比較接近純NaOH溶液腐蝕(本文實驗所得的最低值為12.85%),腐蝕速率比NaOH/NH4F體系的略低。為了進一步的深入研究,實驗測定了三種腐蝕體系的拉曼光譜,結(jié)果發(fā)現(xiàn)這三種腐蝕體系和硅片表面硅酸鹽的聚合都有明顯變化,其聚合程度都是NaOH/NH4F/Na2CO3體系強于NaOH/NH4F體系,NaOH/NH4F體系又強于純NaOH溶液,并且都沒有Si-F鍵存在。 基于這些實驗結(jié)果,本文提出了腐蝕-聚合理論。這一理論認為硅腐蝕后的表形貌受產(chǎn)物硅酸鹽聚合的影響,聚合所產(chǎn)生的氧化硅是金字塔、小山丘和山鏈形成的微掩膜。在堿性含氟溶液中,硅腐蝕的中間產(chǎn)物為SiHxFy(OH)z,它并不穩(wěn)定,最終會變?yōu)楣杷猁}。硅酸鹽的聚合方式有三種：path1(親核脫質(zhì)子硅醇三Si-O-與中性硅酸鹽物種的反應(yīng))、path2(Si-OH群的橋接反應(yīng))和path3(Si-F直接與Si-OH反應(yīng))。path1和path2聚合所形成的產(chǎn)物聚合度低,path3不僅能在硅酸鹽濃度低時發(fā)生而且產(chǎn)物的聚合度還比較高。純NaOH溶液聚合按path1和path2進行,所形成的微掩膜尺寸最小,表面小丘為金字塔。NaOH/NH4F體系三種聚合方式都發(fā)生,所形成的微掩膜尺寸較大,硅表面為條狀小山丘覆蓋。C032-離子雖也能促進聚合,但加入純NaOH溶液只能增加金字塔的密度,而加入NaOH/NH4F體系與F-離子共同作用卻能提高聚合度,使條狀小山丘變成長長的山鏈。根據(jù)腐蝕過程中硅表面反應(yīng)物H2O和OH-離子的濃度變化以及氧化硅掩膜的形成,腐蝕-聚合理論解釋了本文三種腐蝕體系形成的表形貌差異。再結(jié)合腐蝕過程中表形貌引起的腐蝕速率變化,它還能解釋一些其它實驗現(xiàn)象,如金字塔崩頂和各種添加劑的影響等。 基于腐蝕-聚合理論,本文建立了腐蝕-聚合原子模型。這一模型不僅解釋了多種形狀的小丘形成,還解釋了它們形成的難易程度。金字塔是以一個氧化硅頂點為掩膜形成的小丘,其氧化物聚合度最低,最易于形成。(111)條狀小丘以氧化硅密度最高、最不易形成的多個氧化硅頂點為掩膜,所以(111)條狀小丘很難形成。六面小丘以氧化硅密度相對(111)條狀小丘較低的多個頂點為掩膜,相對容易形成,本文NaOH/NH4F體系腐蝕出的小丘就近似這種形狀。此外,氧化硅掩膜若中途形成在金字塔的(111)面上則會形成(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)面的傾角變小,金字塔發(fā)生延展,這解釋了金字塔的傾角小于理論值54.735°；若(111)面上氧化硅形成得很多,(110)面不可忽略,那么金字塔變成八面錐,這解釋了八面錐的出現(xiàn)。 腐蝕-聚合理論及其模型成功解釋了金字塔初始形成以及腐蝕過程中表形貌變化、腐蝕速率變化等實驗現(xiàn)象,成為Si表面腐蝕技術(shù)的理論組成部分,為高效率、低成本硅太陽電池的研究開發(fā)奠定了較好的理論基礎(chǔ)。
[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
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM914.4
本文編號：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
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM914.4
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