本研究以電漿輔助分子束磊晶(Plasma-Assisted Molecular Beam Epitaxy)技術，在鋰酸鎵基板(LiGaO2)上成長M-plane的氮化鎵(GaN)薄膜。在初期的實驗中發現，GaN直接成長在LiGaO2基板上時，以多晶形式成長，且在製程後易發生剝落情況。由原子力顯微鏡觀察LiGaO2基板表面發現，有許多顆粒存在在基板上。因此，如何改善基板的表面是M-plane氮化鎵(GaN)薄膜成長在LiGaO2基板重要關鍵。
我們發現基板經酸洗並在高溫退火後，可改善GaN剝落情況。我們比較基板在真空及大氣的退火環境對基板表面的影響，在原子力顯微鏡觀察結果發現，大氣中退火的LiGaO2基板最為平整。以X-ray繞射分析GaN成長在真空及大氣退火的基板結晶品質，GaN成長在大氣退火的基板的磊晶品質最好且薄膜內應力最低，顯示GaN薄膜剝落的原因是由於過大的薄膜內應力所致。Polar-dependent PL量測成長樣品的發光強度隨著試片旋轉角度到90°達到最高值，顯示試片確實是M-plane GaN。以高解析穿透式電子顯微鏡觀察樣品的微結構，發現GaN薄膜內部Stacking fault的缺陷與LiGaO2表面的cubic-Ga2O3 nano-particle有關，比較真空及大氣的退火LiGaO2基板Ga2O3 nano-particle數量，發現大氣的退火LiGaO2基板Ga2O3 nano-particle數量較少，因此GaN結晶品質較佳。
　　綜合以上的實驗結果發現，未經過退火處理的鋰酸鎵基板，不利於氮化鎵薄膜的成長，顯示基板的表面前處理及熱退火對M-plane的氮化鎵(GaN)薄膜成長有關鍵性的影響。

　In this thesis, we have studied the growth of M-plane GaN thin film on LiGaO2 (100) substrate by Plasma-Assisted Molecular Beam Epitaxy. We found that the growth of GaN thin films on as-received LiGaO2 substrates is poly-crystalline by analysis of X-ray diffraction, and these of GaN thin films were peeled off after thin film process. Using atomic force microscopy (AFM) to scan the surface of as-received LiGaO2 substrate, we found that many particles which are Ga2O3 existed on the surface of as-received LiGaO2.
The annealing ambient for LiGaO2 substrates in vacuum and air ambient has been studied in order to improve the surface of LiGaO2. The scanning results of AFM shows that the crystal quality and stress of M-plane GaN grown on LiGaO2 (100) substrate pre-annealed in air ambient is significantly improved. We conclude that the reason of GaN peeling off from LiGaO2 substrate is attributed to stress between GaN/ LiGaO2.
The measurement of polarization-dependent PL shows that the luminescence intensity of growing sample increases and reaches a maximum at φ = 90° (E⊥c), which indicates the growing samples is M-plane GaN as well. The microstructure of growing samples was characterized by transmission electron microscopy. We found that the formation of stacking fault in GaN is attributed to the growth of GaN on cubic-Ga2O3 nano-particles. The formation of Ga2O3 nano-particles can be suppressed by pre-annealing LiGaO2 substrate in air.
It revealed that the thermal annealing LiGaO2 substrate in air ambient can improve the surface of LiGaO2 substrate effectively, and then one can grow a high quality M-plane GaN thin film on the LiGaO2 substrate.

利用電漿輔助分子束磊晶在LiGaO2基板上生長M-plane GaN之特性分析 i
論文審訂書.........................................................ii
中文摘要 ii

Abstract iv

第一章 前言 1

第二章實驗儀器與原理 9

2-1　反射式高能量電子繞射 9
2-2　原子力顯微鏡 11
2-3　掃描式電子顯微鏡(SEM) 14
2-4　X光繞射儀 17
2-5　光致螢光原理(photoluminescence,PL) 19
2-6　穿透式電子顯微鏡 21

第三章　實驗儀器與步驟 23
3-1　掃描式電子顯微鏡 23
3-2　光致螢光測量 (photoluminescence ,PL) 29
第四章 實驗結果與分析 31

4-1.1未經熱退火處理之LiGaO2基板以磷酸蝕刻之表面分析 31
4-1.2未退火LGO基板上成長GaN 32
4-1.3未退火LGO基板上成長GaN結構分析 35
4-1.4未退火LGO基板上成長GaN表面形貌分析 36

4-2.1經熱退火處理LiGaO2基板之分析 39
4-2.2 GaN成長在經熱退火處理LiGaO2基板 43
4-2.3 GaN成長在經熱退火處理LiGaO2基板之晶體結構分析 45
4-2.4 GaN成長在經熱退火處理LiGaO2基板之表面形貌分析 47
4-2.5 GaN成長在經熱退火處理LiGaO2基板之光性分析 52
4-2.6 GaN成長在經熱退火處理LiGaO2基板之微結構分析 54

結論 64

Reference 66

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