The cathodic deposition of iron–cobalt alloys inside the pores of anodically formed nanoporous silicon (PS) from p-type Si substrate is investigated with respect to the electrolyte composition. The samples were characterized by scanning electron microscopy, energy dispersive spectrometry, Auger electron spectroscopy, and Fourier transform infrared spectroscopy. Results showed that the nucleation of pure cobalt started at the bottom of the pores and the nucleation of pure iron occurred all over the pore walls, leading to a preferential deposition on top surface of the porous layer. Nevertheless, a low concentration of Co2+ ions (5 at.%) in the electrolyte drastically improved the penetration of iron into the pores. As a result, a good filling of the pores with Co metal as well as with Fe–Co alloys was achieved. It was also shown that the deposition process oxidizes the structure mainly at the pore walls. The results of our investigation indicate that the mechanisms occurring during the electrodeposition of metals on porous p-type silicon substrates are completely different depending on the kind of electrolyte used: pure iron-based electrolyte or cobalt-based solutions. A complete understanding of the deposition process requires further analyses of the carrier transport in PS and of the charge exchange at the Si/electrolyte and PS/electrolyte interfaces. These new results involving the deposition of iron-group materials into porous p-type silicon are useful for future silicon technologies.
研究了铁钴合金在由 p 型硅衬底经阳极氧化形成的纳米多孔硅(PS)孔隙内的阴极沉积与电解液成分的关系。样品采用扫描电子显微镜、能量色散光谱仪、奥格电子能谱仪和傅立叶变换红外光谱仪进行表征。结果表明,纯钴的成核始于孔隙底部,而纯铁的成核则遍布孔隙壁,从而优先沉积在多孔层的顶面。然而,电解液中低浓度的 Co2+ 离子(5%)极大地改善了铁对孔隙的渗透。因此,Co 金属和铁-Co 合金很好地填充了孔隙。研究还表明,沉积过程主要氧化了孔壁结构。我们的研究结果表明,多孔 p 型硅衬底上的金属电沉积过程中发生的机理完全不同,这取决于所使用的电解质类型:纯铁基电解质或钴基溶液。要全面了解沉积过程,需要进一步分析 PS 中的载流子传输以及硅/电解质和 PS/电解质界面上的电荷交换。这些涉及将铁组材料沉积到多孔 p 型硅中的新成果对未来的硅技术非常有用。