利用鋁奈米光柵結構產生表面電漿子耦合效果來提升氮化鋁鎵深紫外光量子井的內部量子效率

Internal Quantum Efficiency Enhancement of Deep-ultraviolet AlGaN Quantum Wells through Surface Plasmon Coupling with an Al Nano-grating Structure

陳韋翰(Wei-Han Chen)

指導教授 ： 楊志忠

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201601297

摘要

我們使用金屬有機化學氣相沉積的方式，成長氮化鋁鎵深紫外光量子井，並在上面成長123奈米的氮化鋁鎵覆蓋層。然後，我們在覆蓋層製作一維鋁奈米光柵結構產生表面電漿子耦合效果，來提升氮化鋁鎵深量子井的內部量子效率。透過量測低溫到室溫的光激發螢光頻譜，並且透過偏振片收光做比較，得出垂直極化和水平極化的內部量子效率。因為重(輕)電洞能階和分裂價帶的能階差異很小，導致垂直極化和水平極化的內部量子效率無顯著差異。垂直極化和水平極化有相近的內部量子效率，也可能是因為表面電漿子共振同時和垂直極化和水平極化的躍遷耦合。當發光極化方向和鋁光柵溝槽方向互相垂直時，耦合的表面電漿子共振模態由局域表面電漿子共振主導。當發光極化方向和鋁光柵溝槽方向互相平行時，耦合係由表面電漿極化子和局域表面電漿子結合而成。在激發雷射極化方向和鋁光柵溝槽方向互相垂直時，局域表面電漿子與雷射作用，產生更強的雷射激發而造成更高的內部量子效率。我們也發現鋁光柵結構底部和量子井的距離越近，量子井之內部量子效率越大。

關鍵字

表面電漿子 ； 鋁奈米光柵結構 ； 氮化鋁鎵量子井 ； 深紫外光 ； 內部量子效率

並列摘要

The enhancement of internal quantum efficiency (IQE) of deep-ultraviolet (UV) AlxGa1-xN/AlyGa1-yN (x < y) quantum wells (QWs) by fabricating one-dimensional Al nano-gratings on a QW structure for inducing surface plasmon (SP) coupling is demonstrated. Through temperature-dependent photoluminescence (PL) measurement, the enhancements of IQE in different emission polarizations are illustrated. Due to the small difference in energy band level between the heavy/light hole and split-off valence bands, the IQEs of the transverse-electric- (TE-) and transverse-magnetic- (TM-) polarized emissions are about the same. With SP coupling, the similar IQEs between different polarizations can also be attributed to the simultaneous SP couplings of the TE- and TM-polarized transitions. When emission polarization is perpendicular to Al-grating ridge, the SP resonance mode for coupling with the QWs is dominated by localized surface plasmon (LSP). When emission polarization is parallel with Al-grating ridge, the coupled-SP resonance mode mixes LSP and surface plasmon polariton. When the excitation laser polarization is perpendicular to Al-grating ridge, the strong LSP resonance at the excitation laser wavelength leads to stronger excitation and hence higher IQE levels. The IQE enhancement decreases with the distance between Al-grating ridge tip and the QWs.

並列關鍵字

Surface Plasmon ； Al Nano-grating Structure ； AlGaN Quantum Wells ； Deep-ultraviolet ； Internal Quantum Efficiency

參考文獻

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