本論文研究旨在利用水熱法(Hydrothermal Growth, HTG)成長氧化鋅奈米結構－氧化鋅奈米管(ZnO nanotubes, ZnO NTs)於傳統氮化鎵發光二極體表面再利用PECVD沉積SiO2於氧化鋅奈米管結構表面，製備出具表面粗化及折射係數漸變結構，提升傳統氮化鎵發光二極體之發光效率。
本論文研究架構主要分為兩個部分，第一部分為理論模擬分析，係透過光學模擬軟體(TracePro)以分析不同氧化鋅奈米結構及包覆二氧化矽於氧化鋅奈米管之厚度對傳統氮化鎵發光二極體之光析出效率影響。由模擬結果顯示，具60 nm二氧化矽包覆氧化鋅奈米管結構之氮化鎵發光二極體，可獲得最佳之光析出效率改善；第二部分則集中於實驗研究，本論文採用水熱法製備氧化鋅奈米線於傳統氮化鎵發光二極體表面，再利用低溫之逆反應成長出奈米管結構。從實驗結果顯示，具60±10 nm二氧化矽包覆氧化鋅奈米管結構之氮化鎵發光二極體元件於注入電流350 mA時，與傳統氮化鎵發光二極體相較，其光析出效率增加30.13%。
此證實本研究結構如所預期，確實可藉由氧化鋅奈米結構之表面粗化及折射係數漸變提升光析出效率。並可將此包覆二氧化矽氧化鋅奈米管結構應用於發光二極體或太陽能電池表面提供表面粗化與折射系數漸變之抗反射層，以提升元件之效率。

The present thesis is devoted to further improve the light output of light emitting diodes (LEDs). The use of SiO2/ZnO nanotube arrays (NTAs) which provides an efficient surface roughening scheme with the graded refractive index to effectively maximize light extraction efficiency through releasing total internal reflection (TIR) and minimize Fresnel loss was proposed and demonstrated.
There are two parts comprised in this work. The first part focuses on the simulation and design of SiO2/ZnO NT As for LEDs. The optical simulation software, TracePro, was used to simulate the structures effects of SiO2/ZnO NT As (with different ZnO nanostructures and SiO2 coating thickness) on the light output efficiency of LEDs. An optimum design for SiO2/ZnO NT As with ZnO nanotube arrays and a deposited thickness of 60 nm has been obtained.
The second part of the present study aims at the preparation of LEDs with SiO2/ZnO NT As. The hydrothermal growth method (HTG) was conducted to the p-GaN surface with ZnO NT As. A 60-nm-thick SiO2 layer with a typical refractive index of around 1.5 was coated on the ZnO NTs using a plasma-enhanced CVD system. Material analysis including surface morphology, components, transmittance, and photoelectrical properties of the prepared LEDs are examined and results are presented and discussed.
A considerable improvement in Lop of proposed LEDs by 30.13% at 350 mA, as compared with that of the regular LEDs, has been achieved, which could be attributed to the SiO2/ZnO NT As structure can effectively release TIR and minimize the Fresnel loss. It is expected that the proposed SiO2/ZnO NTAs graded refractive index surface roughening could enhance the light output of GaN-based LEDs for application of solid state lighting.

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