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標題: | 利用表面鋁奈米顆粒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發光效率 Emission Efficiency Enhancement of Deep-ultraviolet AlGaN Quantum Wells through Surface Plasmon Coupling with Surface Al Nanoparticles |
作者: | Yi-An Chen 陳怡安 |
指導教授: | 楊志忠 |
關鍵字: | 鋁奈米顆粒, Al Nanoparticle, |
出版年 : | 2016 |
學位: | 碩士 |
摘要: | 本研究顯示對鋁的薄膜做高溫熱退火可製作鋁的奈米顆粒來產生表面電漿
子耦合效果,能提升氮化鋁鎵深紫外光量子井的內部量子效率。藉由比較不同製作鋁奈米顆粒的條件,包括在高溫熱退火前鋁薄膜的厚度、高溫熱退火的溫度、高溫熱退火時間,可以調整鋁奈米顆粒表面電漿子共振行為。經過最佳化,使表面電漿子共振波長盡可能靠近深紫外光量子井發光波長。 透過變溫光致發螢光可以量測出量子井內部量子效率在不同出光極化方向 的增強。由於重/輕電洞價帶與分離價帶之能帶相差很小,所以橫向電波與橫向磁波極化出光的內部量子效率大約相同。透過表面電漿子耦合增強後,不同偏振方向的內部量子效率也差不多的,原因應該是表面電漿子會同時和橫向電波與橫向磁波耦合。表面電漿子也可能和激發雷射耦合增強雷射激發而量到較高的內部量子效率。內部量子效率的增強會隨著量子井與奈米顆粒結構的距離減少而增加。製作完成的鋁奈米顆粒表面會形成一層氧化層,但這氧化層只有幾奈米厚,對於表面電漿子耦合不會有太大的影響。 The enhancement of internal quantum efficiency (IQE) of deep-ultraviolet (UV) AlxGa1-xN/AlyGa1-yN (x < y) quantum wells (QWs) by fabricating surface Al nanoparticles (NPs) on a QW structure through thermally annealing an Al thin film for inducing surface plasmon (SP) coupling is demonstrated. By comparing the localized surface plasmon (LSP) resonance behaviors of Al NPs formed with different deposited Al-film thicknesses, annealing temperatures and durations, optimized fabrication conditions are obtained for producing LSP resonance close to the QW emission wavelength in the deep-UV range. 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. The strong LSP resonance at the excitation laser wavelength may lead to stronger excitation and hence higher IQE levels. The IQE enhancement decreases with the distance between surface Al NPs and the QWs. The surface Al NPs can be oxidized after they are fabricated. However, the thin oxidization layer of a couple nm in thickness does not significantly affect the SP coupling effects. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/50557 |
DOI: | 10.6342/NTU201601232 |
全文授權: | 有償授權 |
顯示於系所單位: | 光電工程學研究所 |
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