本論文討論利用分子束磊晶成長出的氮化鎵奈米柱之光學性質。利用分子束磊晶所成長出的氮化鎵奈米柱呈垂直於基板的排列，其單一的氮化鎵奈米柱可視為一個應力完全釋放的單晶結構，依據螢光光譜量測，氮化鎵奈米柱具有激子的發光特性且有很好的發光效率。此外，分析反射光譜可以推得氮化鎵奈米柱可效為一層低折射系數的介質，其適用範圍除了過去所報導過的吸收區域 (紫外光波段) 還包括了整個穿透區域 (可見光區)。除了整體的光學特性，也分析了單一的氮化鎵奈米柱的極性螢光的特性，在次波長的範圍下(30-90 nm)其線性極化的程度會和奈米柱直徑相關，這個現象可以用光場受材料的侷限來解釋，由於這個機制只和介電系數和材料尺度有關，我們認為這樣的極化特性也可以出現在其他的半導體材料上或者其他型式的光學量測上，例如電流或電場所激發的螢光。氮化鎵奈米柱除了保有氮化鎵的優點 (例如:可n 型和p 型參雜、良好的穩定性)，其優秀的光學特性將可在未來的光電應用中扮演更重要的角色。

Based on our optical measurements results, we confirm that PAMBE-grown wurtzite GaN nanorods are completely relaxed, strain-free single crystals. The high emission efficiency and excitonic properties of GaN nanorods have been demonstrated. Moreover, vertically aligned GaN nanorod arrays can act as subwavelength low-refractive-index optical media in both transparent and opaque regions. We have also found that the optical confinement effects dominate the linearly polarized properties of GaN nanorods with diameters in the subwavelength regime of 30−90 nm. We believe that the polarized luminescence reported here for GaN can also be found for other semiconductor materials and for other optical measurements, such as electroluminescence and cathodoluminescence. Because of the superior material properties of GaN nanorods in terms of optical transparency, availability of n- and p-type conductivity, and excellent thermal and chemical stabilities, these results could have important implications for nanophotonics and optoelectronics applications.

Chapter 1 Introduction1.1 Growth of One-dimensional Nanostructures1.2 Optical Properties of GaN epilayers1.3 OutlineChapter 2 Eptaxial Growth and Optical Characterization System2.1 Introduction2.2 Molecular Beam Epitaxy (MBE)2.3 Photoluminescence (PL) and m-PL Systems2.4 Reflectivity Measurement SystemsChapter 3 Fundamental Properties of GaN nanorods3.1 Introduction3.2 Growth of GaN Nanorods on Si(111) by PA-MBE3.3 Structural Characterizations 3.4 Luminescence Properties of GaN nanorods3.5 Polarity and Chemical Etching of GaN Nanorods3.6 ConclusionChapter 4 Reflectivity Measurement 4.1 Introduction4.2 Reflectivity of GaN epilayers4.3 Simulation of reflectivity measurement of epilayers 4.4 Reflectivity of GaN nanorod4.5 Simulation of reflectivity measurement of nanorods 4.6 ConclusionChapter 5 Polarized Photoluminescence Measurement of Single GaN nanorod5.1 Introduction5.2 Manipulation of GaN Nanorods5.3 Polarized Photoluminescence Measurement5.4 Size Dependence of Polarized Photoluminescence5.5 Polarized Photoluminescence at Low Temperature5.6 ConclusionChapter 6 ConclusionsReference

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