本文將討論以電漿輔助分子束磊晶系統在鋁酸鋰基版上成長之氮化鎵的特性。我們發現沿[0001] 成長的氮化鎵會在兩個沿方向 成長的氮化鎵平台間長出。其半徑大小約200∼600 奈米，高度約300 奈米。而進一步的研究指出，此奈米晶體有兩種生長模式：其一為自鋁酸鋰基版成長，另外一種為由 方向成長的平台經缺陷轉換而成。之後我們試著改變氮/鎵流量比，並歸納出結晶品質與表面粗糙度的關係，期望能藉由改變成長參數進而控制奈米晶體的數量及大小，以及提高沿 方向成長的氮化鎵的品質。相信在發光元件或自旋電子元件上有更好的應用。

The group III nitride semiconductor grown on c-plane sapphire by radio frequency plasma assisted molecular beam epitaxy has been studied. To archive good quality GaN thin film, nitridation and low temperature AlN buffer layer were applied to overcome the issue of lattice mismatch. Low temperature and long period nitridation process shows better improved of optical properties and crystal quality of GaN film. Buffer layer grown with slightly Ga-rich, substrate temperature at 600℃, for 20 minutes leads to better GaN thin film. High substrate temperature and sufficient nitrogen to gallium ratio are two important factors to control the growth of the good quality GaN epilayer.
We have grown M-plane GaN films with self-assembled c-plane GaN nanopillars on a γ-LiAlO2 substrate by plasma-assisted molecular-beam epitaxy. The diameters of the basal plane of the nanopillars are about 200 to 900 nm and the height is up to 600 nm. The formation of self-assembled c-plane GaN nanopillars is through nucleation on hexagonal anionic bases of γ- LiAlO2. Dislocation defects were observed and analyzed by transmission electron microscopy. From the experimental results, we developed a mechanism underlying the simultaneous growth of three-dimensional c-plane nanopillars and two dimensional M-plane films on a γ-LiAlO2 substrate.

摘 要 1
Abstract 2
CHAPTER 1 4
Introduction 4
CHAPTER 2 7
Growth and Characteristics 7
2.1 Radio frequency plasma assisted molecular beam epitaxy 7
2.2 Growth procedure for sapphire 9
2.2.1 Sapphire preparation 9
2.2.2 Nitridation 9
2.2.3 Buffer layer 10
2.2.4 GaN epilayer 11
2.3 Growth procedure for LiAlO2 11
2.3.1 γ-LiAlO2 preparation 11
2.4 Characteristic measurements 11
2.4.1 Reflective high energy electron diffraction 11
2.4.3 X-ray diffraction 12
2.4.4 Field emission scanning electron microscopy 13
2.4.5 Atomic force microscope 14
2.4.6 Focused ion beam 14
2.4.7 Transmission electron microscopy 15
2.4.8 Hall Effect measurement 16
CHAPTER 3 20
GaN epilayer on sapphire 20
InxGa(1-x)N/GaN heterostructure on sapphire 23
Two step epitaxy growth[24] 28
CHAPER 4 29
GaN epilayer on γ-LiAlO2 29
4-1 M-plane and c-plane GaN 29
4-2 Sample growth 30
4-3 Experiment Results 31
N/Ga flux ratio influence 43
Buffer-layer influence 50
CHAPTER 5 57
Conclusions 57
Reference 58

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