在量子井結構上表面奈米孔洞內的發光、福斯特共振能量轉換與表面電漿子耦合行為的模擬研究

Abstract

本研究利用數值模擬方法探討在氮化鎵量子井結構的表面奈米孔洞內量子點的發光、量子點之間的福斯特共振能量轉換以及量子井和量子點間的福斯特共振能量轉換行為。此外，我們也將銀奈米顆粒置入奈米孔洞中和量子井及奈米孔洞內的量子點產生表面電漿子耦合。我們的結果顯示，藉由奈米孔洞結構產生的奈米腔體效應可以增強量子點的發光與福斯特共振能量轉換效率，也可增強量子井和量子點之間的福斯特共振能量轉換效率，而表面電漿子耦合可以更進一步地加強這些作用，這些作用都和極化方向有高度的相依性。另外，我們發現量子井偶極子與置入淺洞的量子點藉由表面的銀奈米顆粒產生的表面電漿子耦合也可以增強量子井及量子點的福斯特共振能量轉換效率。為此，我們必須仔細設計位於表面的銀奈米顆粒之幾何形狀才能達到此增強效果。我們所觀察的發光和福斯特共振能量轉換效率之增強效果係透過和由光阻與氮化鎵所組成的半空間結構的控制組及由光阻為材料的均勻空間結構組成的對照組比較後所得到的結論。在計算上，我們將施體的強度增強效率乘上受體的輻射增強效率可以得到福斯特共振能量轉換的增強效率。

In this research, numerical simulations on the behaviors of quantum dot (QD) emission, Förster resonance energy transfer (FRET) between QDs, and FRET from quantum well (QW) into QD are performed when QDs are inserted into a surface nano-hole fabricated on a GaN QW template. Meanwhile, an Ag nanoparticle (NP) is also inserted into the surface nano-hole for inducing the surface plasmon (SP) coupling with the QW and inserted QD. The nanoscale-cavity effect produced by the nano-hole structure enhances the emission and FRET efficiencies of the QDs, and the FRET from QW into QD. The SP coupling can further enhance the efficiencies of those processes. High polarization dependencies are observed in all those processes. Meanwhile, a surface Ag NP for producing the SP couplings with an embedded QW-dipole and a QD inserted into a shallow hole can enhance the FRET from the QW into the QD. However, such an enhancement requires a careful design for the surface Ag NP geometry. The enhancements of emission and FRET are demonstrated through the comparisons with a control structure of two half-spaces and a reference structure of a homogeneous space. The FRET enhancement is obtained by multiplying the donor intensity enhancement and the acceptor radiated power enhancement.