单根金刚石纳米锥/Pd纳米粒子复合结构LSPR增强光电转换特性与机制研究

For designing opto-electronic devices enhanced by Localized Surface Plasmon Resonance (LSPR), we should not only concern about the enhanced light-harvesting efficiency by modulating localized surface plasmon(LSP), but also show more interests in the issue of carrier separation and injection excited by SPR, that is, the issue for plasmon-to-electricity conversion efficiency(PECE). However, the direct extraction of relation between local optical near-field distribution and carrier excitation is unobtainable in macroscopic devices nowadays, which makes the appreciation of LSPR-enhanced PECE difficult. A proposal has been presented for constructing a composite SPR structure of individual diamond nanocone/Pd nanoparticles, which shows two-fold photon-harvesting ability (large aspect ratio of nanocone and SPR of metal nanoparticels) and can be employed as applicable solution for above-mentioned problem. Based on the measurement and simulation of local optical near-field for this composite SPR nano-unit, in combination with its electrical properties of photo-conductance and vacuum field electrons emission, the PECE of local optical near-field can be directly extracted. The enhancement mechanism of hot electrons injection to PECE will be discussed, and the relaxation dynamics of photo-electrons in this composite SPR nano-unit will be studied. Ultimately, we will establish the mechanism for LSPR enhanced opto-electronic properties in this nano-unit. This composite SPR nano-unit can be used to fabricate visible-blind UV detector and light-assisted field electron emission source.

在局域表面等离激元共振（LSPR）增强光电器件的设计中，不仅要关心如何调控局域表面等离激元增强光吸收，更要关心SPR对载流子的激发，即SPR的光电转换问题。但是，目前无法从宏观器件本身得到局域光学近场分布与局域界面电子激发之间的直接联系，从而难以评价LSPR的光电转换效率。单根金刚石纳米锥/Pd纳米粒子SPR复合结构具有双重的光子捕获效应(纳米锥的高长径比结构+LSPR)，并为以上问题的解决提供了可能。基于对复合SPR纳米单元光学近场特性的测试和模拟，结合对纳米单元光电导以及真空电子发射特性的测量，可以获得复合纳米单元的SPR增强光电转换效率。我们将研究金属纳米粒子中SPR弛豫所激发的热电子对于光电转换的增益机制，并研究单根金刚石纳米锥SPR复合结构中光电子弛豫的动力学过程。我们将最终建立金刚石纳米锥单体SPR增强光电特性的具体物理机制，并制作SPR增强"日盲"紫外探测器和光辅助场电子源。