臺灣博碩士論文加值系統

氮化硼(boron nitride, BN)近年來成為深紫外光發光二極體所需的理想P型材料，因此具備sp2鍵結的六方氮化硼(h-BN)受到很大關注，h-BN具備高能隙(~ 6.0 eV)與低電洞活化能(~ 30 meV)，能使深紫外光不被氮化硼吸收，還能大幅提升電洞濃度，增加元件的外部量子轉換效率。
然而同為sp2鍵結的菱形(rhombohedral)氮化硼(r-BN)，其晶格結構與六方氮化硼相似，在常用的X射線繞射儀(x-ray diffraction, XRD)量測中，六方氮化硼與菱形氮化硼的訊號位置幾乎重疊，兩者僅差不到0.1°，無法明確分辨六方氮化硼與菱形氮化硼的結構。因此，我們藉由高解析度穿透式電子顯微鏡(high resolution transmission electron microscopy, HRTEM)的影像，觀察h-BN與r-BN在晶格結構上的差異。
為了得到高品質的BN的磊晶層，本研究利用有機金屬氣相沉積法(metal-organic chemical vapor deposition, MOCVD)成長BN，先在藍寶石基板上成長單晶氮化鋁(AlN)，再接著成長BN。我們透過五三比的調變來改善BN的晶格品質，並藉由XRD及HRTEM分析BN的晶格結構。根據三組五三比(2454、663、237)的分析結果，我們發現h-BN與r-BN會共存於磊晶層，且五三比為663的BN磊晶層有最佳的晶格品質。

Hexagonal Boron Nitride (h-BN) with sp2 bonding is an attractive p-type material for the application in deep-ultraviolet light emitting diodes (DUV LEDs). This is due to the wide bandgap (~ 6.0 eV) and low activation energy of acceptors (~30 meV) of h-BN, rendering high transmission of DUV photons and high p-type conductivity for DUV LEDs.
However, rhombohedral BN (r-BN), also with sp2 bonding, is of a similar lattice structure with h-BN, which yields almost identical X-ray diffraction (XRD) angles. With the diffraction-peak difference less than 0.1°, h-BN and r-BN can not be differentiated by XRD patterns alone, but requires high-resolution transmission electron microscope (HRTEM) to reveal the minor difference in lattice between h-BN and r-BN.
In this study, we perform epitaxial growth of BN by metal-organic chemical vapor deposition (MOCVD) on single-crystalline aluminum nitride (AlN), which is previously grown on the sapphire substrate. In order to improve the crystal qualities of BN, V/III ratios (i.e. the molar-flow ratio of NH3 to triethylborane) was varied from 237 to 2454. According to the characterization results with XRD and HRTEM, the MOCVD-grown BN wafer contains hexagonal and rhombohedral lattices at the BN/AlN interface, and the wafer grown with the V/III ratio of 663 exhibit superior qualities to those attained with the ratios of 237 and 2454.

目錄
中文摘要……………………………………………………………………………....................I
英文摘要…………………………………………………………………………....................II
致謝………………………………………………………………………………....................III
目錄……………………………………………………………………………….....................IV
圖目錄…………………………………………………………………………….....................V
表目錄…………………………………………………………………………...................VIII
第一章、 緒論……………………………………………………………………………............1
1.1. 深紫外光發光二極體的技術現況……………………………………….......1
1.2. 氮化硼結構與特性………………………………………………………............2
1.3. 氮化硼應用於深紫外光發光二極體的優勢……………………………....5
1.4. 五三比對三五族材料磊晶的影響……………………………………….......7
1.5. 研究動機與章節架構……………………………………………………...........9

第二章、 實驗方法、製程與儀器………………………………………………………....10
2.1. 有機金屬化學氣相沉積原理………………………………………….........10
2.2. 穿透式電子顯微鏡……………………………………………………............12
2.3. X光繞射儀……………………………………………………………................13

第三章、 分析與討論……………………………………………………………………........15
3.1. 磊晶結構分析(hBN or rBN?)………………………………………….......15
3.2. 五三比的影響…………………………………………………………..............20

第四章、 結論與未來展望……………………………………………………………….......34

參考文獻………………………………………………………………………………….................36

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