利用三維電漿子超穎材料增進量子點發光效益

Abstract

本論文中，我們結合兩種量子點新穎材料和電漿子超穎材料兩個不同領域的材料以提升量子點發光效益。由於本研究中使用能量傳遞得方式使得電漿子超穎材料的表面店漿效應會將能量傳遞給半導體量子點材料做使用，使得逛子點的發光效率提升。然而為達到直接電子的能量傳遞方式；因此，再設計電漿子超穎材料上比需做特殊的設計，史的我們量子點和超穎材料可以得到最佳的耦合效果。 首先，我們先對二維週期結構的非對稱型裂環震盪器做其本身的光特性分析，從模擬跟實驗中我們可以發現非對稱型環形震盪器會產生三種不同的共振模態；因此，我們在設計三維裂環震盪器之前必須先確認哪一種共振模態對我們量子點發光效率最適合，以便我們之後做三維環形震盪器的設計可以達到較佳的效果。從本論文中，我們可以從模擬跟實驗得到證明磁偶極共振方式是最適合我們的量子點發光；因此藉由這樣的結果，我們進行三維電漿子超穎材料的設計和分析。 接著我們設計三維結構的光性分析，藉由改變不同的介電質厚度，其電場強度會被改變；藉由一連串的模擬分析，我們可以得到最佳化的三維裂環震盪器。在製程中我們初步做出三維裂環震盪器；從模擬結果可以知道我們可以利用可調式超穎材料得到量子點發光效率的提升，而當我們把裂環震盪器從二為提升到三維時，其發光效益可疑得到更進一步的提升。

In this thesis, we combine two innovative material: plasmonic metamaterials and semiconductor quantum dots which can be considered as photons and electrons coupling at the microcosmic. Since the excitons and photons are different elementary particle, to finely couple these two kinds of mechanism may face many difficulties. Therefore, we try to control the spontaneous emission of quantum dots by designed plasmonic resonance of metamaterials. First, we analyze the effect of different resonance type from metallic nanostructure on quantum dot emission. We illustrated multiple plasmonic resonances with asymmetric split ring resonantor which offers us several kinds of resoanace. Since the meta-molecule is at the scale of subwavelength and is highly related to the morphology of the fabricated structure. In this study, we fabricate the planar meta-molecule at the feature size of 30 nm and the measured spectra is quite matched to the calculated resonances. Furthermore, to achieve good exciton-plasmon coupling, the magnetic dipole is chosen to match the quantum dot fluorescence wavelength. In short, we successfully propose asymmetric split ring resonator and investigate the enhanced light emission of quantum dot under different kinds of dipole mode which leads us to the following works. We have already informed that the characteristics of magnetic dipole can improve the light emission of quantum dots, therefore, we would like to further enhance quantum dot fluorescence via the structure which is sandwiched with insulator. Owing to the difference of refractive index and surface plasmon, the electric field will be enhanced around the metal surface and inside the insulator layers. We optimized the thickness of the SiO2 and the numbers of the layer, and simulate the stacking metamaterial along with our PbS quantum dots. In summary, the enhancement factor of quantum dot can be furthure improved from 3.5 to 4.5 via stacking metamaterials. Such these results can be applied in optical communication, biosensor, fluorescence imaging, and other novel QD-based optoelectronic devices.