We studied the effects of O²⁻ ions on the coordination structure of Si ions and the electrodeposition process of Si films in molten fluorides using SiO₂ powder (as a source of Si) and Li₂O (as a source of O²⁻). High-temperature Raman spectroscopic data revealed that the dissolution of SiO₂ in molten KF, LiF-KF, and LiF-NaF-KF without Li₂O was proceeded by the formation of silicate ions, with the [Si₂O₅]²⁻ ion acting as the dominant species. On the other hand, when 3.0 mol% Li₂O was added to molten LiF-KF and LiF-NaF-KF, the intensity of Raman band due to [SiO₃F]³⁻ ion was increased compared to that without Li₂O system, which indicated that the O²⁻ ions could cause breakage of Si-O-Si bonds of SiO₂ or [Si₂O₅]²⁻ ions. Furthermore, the reduction currents, attributed to the reduction of Si ions, increased significantly by the addition of Li₂O; moreover, the thickness and current efficiency of the electrodeposited polycrystalline Si layer prepared by potentiostatic electrolysis was improved. These results indicated that the O²⁻ ions can change the coordination structure of Si ions in molten fluorides and that the design of the molten salts bath is a key technology for fabricating high-quality Si layers with high current efficiency.

中文翻译：

---

氧化物对熔融氟化物中硅电沉积过程的影响

我们使用SiO ₂粉末（作为Si的来源）和Li ₂ O（作为O ^2-的来源）研究了O ^2-离子对Si离子的配位结构和熔融氟化物中Si膜的电沉积过程的影响。。高温拉曼光谱数据显示，在没有Li ₂ O的情况下，熔融KF，LiF-KF和LiF-NaF-KF中SiO ₂的溶解是通过硅酸盐离子的形成而进行的，其中[Si ₂ O ₅ ] ²⁻离子起主导作用。另一方面，当将3.0mol％的Li ₂ O添加到熔融的LiF-KF和LiF-NaF-KF中时，由于[SiO ₃与无Li ₂ O体系相比，F] ^3-离子增加，这表明O ^2-离子可能导致SiO ₂或[Si ₂ O ₅ ] ^2-离子的Si-O-Si键断裂。此外，归因于Si离子的还原的还原电流通过添加Li ₂ O而显着增加；因此，还原电流显着增加。此外，通过恒电位电解制备的电沉积多晶Si层的厚度和电流效率得到改善。这些结果表明，O ²⁻ 离子可以改变熔融氟化物中硅离子的配位结构，而熔融盐浴的设计是制造高电流效率的高质量硅层的关键技术。