氮化鋁奈米柱層改善發光二極體之效能與葡萄糖濃度感測應用之研究

Light-emitting diodes efficiency improvement with an AlN nanorod template and applications for Glucose-sensing

藍文翊(Wen-Yi Lan)

指導教授 ： 黃建璋

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/NTU201601511

摘要

在本篇論文包含兩個部份的研究，首先是利用高溫爐管在藍寶石基板上成長氮化鋁奈米柱層作為氮化鎵磊晶的緩衝層，使其在磊晶的過程之中產生側向生長的作用，第二部分則是利用氮化鎵發光二極體當作光源來構成葡萄糖濃度感測的系統。
目前約有95%的氮化鎵發光二極體是利用有機金屬化學氣相沉積成長在藍寶石基板上，由於兩者材料的晶格常數及熱膨脹係數的差異，導致氮化鎵磊晶層產生大量的貫穿式差排。為了改善氮化鎵的磊晶品質，我們利用了氣-液-固機制在藍寶石基板上先成長一層氮化鋁奈米柱層，使氮化鎵在成長的過程中產生磊晶側向延長。透過拉曼光譜的量測，我們計算出應力確實從1.25GPa下降至0.78GPa，有著明顯的改善。而透過穿透式電子顯微鏡的影像，相對於直接磊晶於藍寶石基板的氮化鎵發光二極體，發現貫穿式差排的密度明顯的減少，同時我們觀察到在奈米柱上方出現了疊層缺陷，這些疊層缺陷有助於阻擋貫穿式差排穿透至磊晶層表面。最後進行了變溫光激發螢光的測試，發現成長於氮化鋁奈米柱上的發光二極體的內部量子效應提升了12%。
隨著物聯網的發展，生物感測系統結合智慧型手機的研究逐漸蓬勃發展，第二部分的研究是希望透過氮化鎵發光二極體當作光源製作出葡萄糖濃度感測系統，提供一個快速準確的量測平台。首先進行氮化鎵發光二極體光電特性的量測。接著進行葡萄糖濃度的測試，透過折射系數的變化使光行進方向產生偏移，最後由接收端量測角度的變化，我們的系統有良好的線性趨勢，靈敏度能使每單位的折射率產生122°的變化。透過重複性的測試，得到了良好的結果，確保了系統的穩定度。替換光子晶體氮化鎵發光二極體當作光源，雖得到較高的訊號強度，整體的靈敏度沒有太大的改善。最後在飲料糖度檢測的實際應用中進行模擬測試，以及提出了結合於手機系統的雛型。

關鍵字

氮化鎵 ； 發光二極體 ； 氮化鋁 ； 奈米柱 ； 葡萄糖量測 ； 生物感測器

並列摘要

This thesis contains two research projects. First, Aluminium nitride (AlN) nanorod template was developed on the sapphire substrate by the high temperature tube furnace as a nucleation layer for the epitaxy of Gallium nitride (GaN) which leaded to the epitaxial lateral overgrowth during the process. Second, we combined the GaN-based light-emitting diode (LED) into the detection system in order to construct a glucose-sensing platform.
Nowadays, about 95 % of the GaN-based LEDs are made on sapphire by metal-organic chemical vapor deposition (MOCVD). Due to the mismatch of the lattice constant and the thermal expansion coefficient, a large number of threading dislocations (TDs) are generated in the epi-layer of GaN. In order to improve the crystal quality of GaN, Vapor-liquid-solid (VLS) mechanism is used to develop AlN nanorod template on the sapphire substrate which leads to epitaxial lateral overgrowth during the process of epitaxy. From the Raman spectrum analysis, the residual stress of the sample with AlN template is reduced from 1.25 GPa to 0.78 Gpa. By transmission electron microscopy (TEM) images, we can know that the density of the TDs has been reduced. The stacking fault on the nanorod template can block the TDs from penetrating to the surface. Finally, by the temperature-dependent photoluminescence (PL) analysis, we found that the internal quantum efficiency (IQE) of MQWs is enhanced by 12%.
With the development of internet of things (IoT), biosensor combined with smartphone has been a popular research. In this part of the research, we proposed an accurate and quick detection platform which included of GaN-based LED light sources for glucose-sensing. The electro-optical characteristic was first defined. The detection of different glucose solution was then conducted. With the variation of the refractive index, the propagation of the light was altered. The angular peak shift was recorded by our detector. Our system shows a good linear correlation and the bulk refractometric sensitivity is calculated to be 122.73°/RIU. By the repeatability test, our system shows a great result, showing a good stability. The photonic crystal GaN-based LED was substituted for the planar LED as a light source. The result shows that only the intensity has been enhanced while the sensitivity was not improved. Finally, the sugar content in beverage was taken into consideration and the prototype of the portable detection system model was also proposed.

並列關鍵字

Gallium nitride(GaN) ； light-emitting diode(LED) ； Aluminium nitride(AlN) ； nanorod ； glucose-sensing ； biosensor

參考文獻

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