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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/80547

    Title: 六方氮化硼與菱形氮化硼之分析;Characterization of hexagonal Boron Nitride and rhombohedral Boron Nitride
    Authors: 陳宥錚;YuCheng, Chen
    Contributors: 光電科學與工程學系
    Keywords: 氮化硼;六方氮化硼;菱形氮化硼;深紫外光發光二極體;有機金屬氣相沉積法;五三比;Boron Nitride;hexagonal Boron Nitride;rhombohedral Boron Nitride;deep ultraviolet light emitting diodes;metal organic chemical vapor deposition;V/III ratio
    Date: 2019-07-17
    Issue Date: 2019-09-03 14:44:21 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 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.
    Appears in Collections:[光電科學研究所] 博碩士論文

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