Semiconductors have attracted great attention for surface-enhanced Raman scattering (SERS) applications due to their rich variety, adjustable band structure, good chemical stability, and biocompatibility. However, their intrinsic weak SERS activity limited the further development of semiconductor substrates. Here, the α-Fe₂O₃ films with high {} and {} facet exposure ratios were fabricated through an electrodeposition method with the existence of NH₄Cl and CH₃COONa. The α-Fe₂O₃{} and α-Fe₂O₃{} films show excellent SERS properties with enhancement factor of 4.155×10³ and 5.481×10³, as well as the relatively low limit of detection down to 2 × 10⁻⁷ M for 4-nitrobenzenethiol. Meanwhile, the lower relative standard deviation values (<10%) confirm the well uniformity of as-prepared substrates. Ultraviolet photoelectron spectroscopy analysis reveals that the α-Fe₂O₃{} possesses the lower work function, which could guarantee the efficient interfacial charge transfer between substrates and probe molecules. Moreover, first principles calculations further indicates that the charge transfer efficiency on {} facet can be effectively improved, and thus significantly enhance the SERS activity of α-Fe₂O₃. The current study provides a strategy for the fabrication and application of semiconductor-based SERS substrates.

中文翻译：

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α-Fe2O3 薄膜面依赖性 SERS 活性的实验和理论研究

半导体因其丰富的品种、可调节的能带结构、良好的化学稳定性和生物相容性而在表面增强拉曼散射（SERS）应用中引起了极大的关注。然而，它们固有的弱SERS活性限制了半导体衬底的进一步发展。这里，在NH ₄ Cl和CH ₃ COONa的存在下，通过电沉积方法制备了具有高{ }和{ }面暴露率的α-Fe ₂ O ₃薄膜。 α-Fe ₂ O ₃ { } 和 α-Fe ₂ O ₃ { } 薄膜表现出优异的SERS性能，增强因子分别为4.155×10 ³和5.481×10 ³，以及相对较低的检测限低至2 ×  4-硝基苯硫酚为10 ^-7 M。同时，较低的相对标准偏差值（<10%）证实了所制备的基板的良好均匀性。紫外光电子能谱分析表明α-Fe ₂ O ₃ { }具有较低的功函数，可以保证基底和探针分子之间有效的界面电荷转移。此外，第一原理计算进一步表明，可以有效提高{ }面上的电荷转移效率，从而显着增强α-Fe ₂ O ₃的SERS活性。当前的研究为基于半导体的SERS基底的制造和应用提供了策略。