Bitton Ora, Gupta Satyendra Nath, Cao Yong, Vaskevich Alexander, Houben Lothar, Yelin Tamar, Haran Gilad
Chemical Research Support Department, Weizmann Institute of Science, P.O. Box 26, Rehovot 7610001, Israel.
Department of Chemical and Biological Physics, Weizmann Institute of Science, P.O. Box 26, Rehovot 7610001, Israel.
J Chem Phys. 2021 Jan 7;154(1):014703. doi: 10.1063/5.0034739.
Plasmonic cavities (PCs) made of metallic nanostructures can concentrate electromagnetic radiation into an ultrasmall volume, where it might strongly interact with quantum emitters. In recent years, there has been much interest in studying such a strong coupling in the limit of single emitters. However, the lossy nature of PCs, reflected in their broad spectra, limits their quality factors and hence their performance as cavities. Here, we study the effect of the adhesion layer used in the fabrication of metal nanostructures on the spectral linewidths of bowtie-structured PCs. Using dark-field microspectroscopy, as well as electron energy loss spectroscopy, it is found that a reduction in the thickness of the chromium adhesion layer we use from 3 nm to 0.1 nm decreases the linewidths of both bright and dark plasmonic modes. We further show that it is possible to fabricate bowtie PCs without any adhesion layer, in which case the linewidth may be narrowed by as much as a factor of 2. Linewidth reduction increases the quality factor of these PCs accordingly, and it is shown to facilitate reaching the strong-coupling regime with semiconductor quantum dots.
由金属纳米结构制成的等离子体腔（PCs）可以将电磁辐射集中到一个超小的体积中，在这个体积中它可能与量子发射器发生强烈相互作用。近年来，人们对在单发射器极限下研究这种强耦合产生了浓厚兴趣。然而，PCs的损耗特性，体现在其宽泛的光谱中，限制了它们的品质因数，进而限制了它们作为腔的性能。在这里，我们研究了用于制造金属纳米结构的粘附层对蝴蝶结结构PCs光谱线宽的影响。使用暗场显微光谱以及电子能量损失光谱，我们发现我们所使用的铬粘附层的厚度从3纳米减小到0.1纳米会减小亮和暗等离子体模式的线宽。我们进一步表明，可以制造没有任何粘附层的蝴蝶结PCs，在这种情况下，线宽可以缩小多达2倍。线宽的减小相应地提高了这些PCs的品质因数，并且表明这有助于与半导体量子点达到强耦合状态。
