Plasmon-Enhanced Electron Harvesting in Robust Titanium Nitride Nanostructures
Plasmon-Enhanced Electron Harvesting in Robust Titanium Nitride Nanostructures
复制标题
DOI：
10.1021/acs.jpcc.9b03184
复制
发表时间：
2019-08-01
影响因子：
3.7
通讯作者：
Oulton, Rupert F.
中科院分区：
文献类型：
--
作者：
Doiron, Brock;Li, Yi;Oulton, Rupert F.
氮化钛（TiN）继续证明自己是等离子体应用中金的廉价，耐用和有效的替代品。值得注意的是，与金系统相比，TiN具有改善的热电子捕获和光催化能力，我们最近将其归因于TiN及其原生半导体TiO 2-x表面层中氧的作用。在这里，我们探讨了局部表面等离子体共振（LSPRs）的作用，电子捕获在TiN/TiO 2-x界面和探测TiN纳米结构的弹性下的高功率激光照射。为了研究这一点，我们制造TiN条，其中的横向限制允许LSPR的偏振选择性激发。使用超快泵浦-探测光谱，光学特性，和拉曼振动光谱，我们与观察到的电子行为的差异和变化的具体材料的属性。我们观察到等离子体增强的电子捕获超出预期的等离子体模式的增强吸收。我们将此归因于表面氧化物阻尼等离子体共振，提供额外的非辐射损失通道。随后，我们表明，低功率退火的表面氧化层的界面处的陷阱密度降低，并增加了初始收获的电子浓度。TiN的独特性质使其在等离子体激元电子捕获应用的未来发展中具有重要意义。
Titanium nitride (TiN) continues to prove itself as an inexpensive, robust, and efficient alternative to gold in plasmonic applications. Notably, TiN has improved hot electron-harvesting and photocatalytic abilities compared to gold systems, which we recently attributed to the role of oxygen in TiN and its native semiconducting TiO2-x, surface layer. Here, we explore the role of localized surface plasmon resonances (LSPRs) on electron harvesting across the TiN/TiO2-x interface and probe the resilience of TiN nanostructures under high-power laser illumination. To investigate this, we fabricate TiN strips, in which the lateral confinement allows for the polarization-selective excitation of the LSPR. Using ultrafast pump-probe spectroscopy, optical characterization, and Raman vibrational spectroscopy, we relate the differences and changes observed in the electron behavior to specific material properties. We observe plasmon-enhanced electron harvesting beyond what is expected resulting from the enhanced absorption of the plasmonic mode. We accredit this to the surface oxide damping the plasmon resonance, providing additional nonradiative loss channels. Subsequently, we show that low-power annealing of the surface oxide layer reduces the trap density at the interface and increases the initial harvested electron concentration. The unique properties of TiN make it important in the future development, of plasmonic electron-harvesting applications.