School of Physics and Technology, Center for Ion Beam Application, Center for Electron Microscopy and Hubei Nuclear Solid Physics Key Laboratory and ‡MOE Key Laboratory of Artificial Micro- and Nano-Structures, Wuhan University , Wuhan 430072, China.
ACS Appl Mater Interfaces. 2017 Apr 26;9(16):14534-14544. doi: 10.1021/acsami.7b03839. Epub 2017 Apr 17.
Surface-enhanced Raman spectroscopy (SERS) is a versatile and powerful spectroscopic technique for substance analysis and detection. So far, the highest detection sensitivities have been realized on noble nanostructure substrates, which, however, are costly, unstable, and non-biocompatible. While semiconductor substrates could in principle be used, existing realizations have either resulted in substrates with low sensitivities or used methods that have poor technical control. Here we report a general and versatile method, based on ion irradiation and vacuum annealing, for fabricating large-scale reduced semiconducting oxide SERS substrates with high sensitivities. The SERS enhancement mainly stems from oxygen vacancy-associated electronic states created by the ion irradiation of sample; these states enhance the charge-transfer (CT) mechanism between the oxide substrate and the adsorbed molecules and thus significantly magnify SERS signals. The improved carrier mobility by vacuum annealing and the introduction of impurity energy levels and nanostructures enhances further the CT efficiency. A detection limit as low as 5 × 10 M was achieved; this is the highest sensitivity among the reported semiconductors, and it even compares to noble metals without the aid of "hot spots". The method is general-we demonstrate it on WO, ZnO, and TiO substrates using Ar and N ion beam irradiation-and broadly applicable to produce noble-metal-free SERS substrates with high sensitivities.
表面增强拉曼光谱（SERS）是一种用于物质分析和检测的多功能、强大的光谱技术。迄今为止，在贵金属纳米结构衬底上实现了最高的检测灵敏度，然而，这些衬底昂贵、不稳定且不具有生物相容性。虽然半导体衬底原则上可以使用，但现有的实现方法要么导致灵敏度较低的衬底，要么使用技术控制较差的方法。在这里，我们报告了一种基于离子辐照和真空退火的通用且多功能的方法，用于制造具有高灵敏度的大规模还原半导体氧化物 SERS 衬底。SERS 增强主要源于样品离子辐照产生的与氧空位相关的电子态；这些状态增强了氧化物衬底和吸附分子之间的电荷转移（CT）机制，从而显著放大 SERS 信号。真空退火提高了载流子迁移率，并引入了杂质能级和纳米结构，进一步提高了 CT 效率。检测极限低至 5×10^-7 M；这是报道的半导体中最高的灵敏度，甚至与没有“热点”辅助的贵金属相比也毫不逊色。该方法具有通用性——我们使用 Ar 和 N 离子束辐照在 WO、ZnO 和 TiO 衬底上进行了演示——并广泛适用于制造具有高灵敏度的无贵金属 SERS 衬底。
