四元氮化銦鎵鋁多重量子井與奈米針結構之光學研究與氫氧化鋱奈米顆粒之上轉換光學研究

Optical Study of Quaternary AlInGaN Multiple Quantum Wells and Nanotips and Up-conversion Optical Study of Tb(OH)3@SiO2 Nanoparticles

陳婷姿(Ting-Tzu Chen)

指導教授 ： 梁啟德

共同指導教授 ： 陳永芳(Yang-Fang Chen)

國立臺灣大學/理學院/物理研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.00094

摘要

此論文包含兩大主題，第一部份為四元半導體材料氮化銦鎵鋁多重量子井與奈米針之光學量測與分析，第二部份為二氧化矽包覆氫氧化鋱奈米顆粒之上轉換光學研究。
1.氮化銦鎵鋁多重量子井與奈米針之光學研究
我們研究了氮化銦鎵鋁多重量子井與奈米針的光學性質。在光致螢光實驗中，氮化銦鎵鋁多重量子井與奈米針的波峰能量分別為3.416 電子伏特及3.388 電子伏特，可以觀察到波峰能量有紅移的現象。氮化銦鎵鋁多重量子井與奈米針唯一的差別是他們的幾何結構，因此，造成紅移現象的主因是由於奈米針的應力釋放所導致。由改變激發功率的螢光光譜量測與分析，可以判定氮化銦鎵鋁多重量子井與奈米針的發光機制主要為激子複合發光。由變溫的螢光光譜量測可得到氮化銦鎵鋁多重量子井與奈米針的活化能分別為9.5毫電子伏特與14.58毫電子伏特，奈米針的活化能較大是由於量子侷限效應所造成的。由以上的螢光光譜量測與分析可得應力釋放與活化能大小會造成紅移現象的產生，並確定主要發光機制為激子複合發光。

2.二氧化矽包覆氫氧化鋱奈米顆粒之上轉換光學研究
我們研究了氫氧化鋱奈米顆粒的能階躍遷發光與上轉換發光機制。在光致螢光實驗中，以可變激發光波長的氙燈為激發光源可看到多個能階躍遷發光。由光譜可得發光波長分別為375、412、434、483、539、544、581及618奈米，相對應的能階躍遷為5D3->7FJ (J=4~6) 及 5D4->7FJ (J=3~6)。由光致螢光激發與光致螢光實驗可得不同激發光能量與能帶結構的相關性。在上轉換光致螢光實驗中，以紅光半導體雷射為激發光源，可得上轉換發光波長在470奈米。由於稀土元素的長生命期特性，激發態吸收機制為合理的上轉換的發光機制。

關鍵字

氮化銦鎵鋁 ； 螢光 ； 氫氧化鋱 ； 上轉換

並列摘要

This thesis describes measurements and analysis on the change of emission properties of AlInGaN multiple quantum wells after patterning into nanotip arrays and the up-conversion luminescence in Tb(OH)3@SiO2 nanoparticles.
1. Optical Study of Quaternary AlInGaN Multiple Quantum Wells and Nanotips
We studied the different optical properties of AlInGaN MQWs and nanotips. In the PL spectra, the peak energy of AlInGaN MQWs and nanotips are 3.416 eV and 3.388 eV, respectively, and the redshift phenomenon from MQWs to nanotips was observed. After patterning into nanotip arrays, the only difference between MQWs and nanotips is their geometric structures, and the relaxation of compressive strains which occurred in MQWs leads to the redshift phenomenon from MQWs to nanotips. In addition, according to the power-dependent PL spectra and the fitting curve, the luminescence mechanism of AlInGaN can be considered as excitonic recombination. The activation energies were obtained from the temperature-dependent PL spectra and the Arrhenius fitting, and that of AlInGaN MQWs and nanotips were 9.5 meV and 14.58 meV, respectively. Hence, AlInGaN nanotips which have stain-relaxed lower band gap and higher activation energy can have luminescence with lower photon energy.

2. Visible Photoluminescence and Up Conversion of Tb(OH)3@SiO2 Nanoparticles
We presented the efficient photoluminescence (PL) and up conversion of Tb(OH)3@SiO2 nanoparticles at room temperature. The rich energy structures of Tb ions exhibit a bright emission covering whole visible spectrum, which can be detected by PL experiment under a UV excitation. The sharp and complicated emission bands of Tb ions have been observed at 375 nm, 412 nm, 434 nm, 483 nm, 539 nm, 544 nm, 581 nm, and 618 nm, which correspond to the energy transfer of 5D3->7FJ (J=4~6) and 5D4->7FJ (J=3~6). The photoluminescence excitation (PLE) spectrum of Tb ions represented that the changed excitation wavelengths correspond to the energy distribution of Tb ions. In up-conversion PL spectrum, the blue emission band has been detected at 470 nm, which was excited by a continuous-wave laser at 660 nm, the red light source. The probable up-conversion mechanism may be the excited state absorption (ESA) process due to the long lifetimes of Tb ions.

並列關鍵字

AlInGaN ； PL ； Tb(OH)3 ； upconversion

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