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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/7586

    Title: 銪元素摻雜於氧化鋅奈米線特性研究;Characterization of Eu doped ZnO nanowires
    Authors: 陳重維;Chung-Wei Chen
    Contributors: 物理研究所
    Keywords: 氧化鋅;;Eu;ZnO
    Date: 2008-06-18
    Issue Date: 2009-09-22 11:00:23 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本研究主要使用化學氣相沉積法成長氧化鋅奈米線,研究其材料特性以及成長方式。 本研究使用化學氣相沉積法成功的在矽基板以及氮化鎵基板上成長出氧化鋅奈米線。以氮化鎵作為基板其成長溫度為950度時,所成長出來的氧化鋅奈米線均勻性等向性最佳:在以氮化鎵作為基板的情況下,其成長模式為Stranski Krastanow mode,在低氧濃度容易形成薄膜,在高氧情況下容易形成奈米線,其奈米線的長度約10~15微米,半徑約在80~200奈米。從掃描式電子顯微鏡可以看到氧化鋅奈米線大多垂直氮化鎵基板成長,從X-ray繞射結構分析得知氧化鋅奈米線主要沿著002面成長;以矽做為基板且沒有催化劑的情況下,其成長模式為Volmer-Weber mode。成長溫度為950度時所成長的氧化鋅奈米線長度約10~25微米 ,其直徑約60~150奈米。以矽做為基板且以5奈米厚度的金膜為催化劑的情況下,其成長模式為Vapor-Liquid-Solid mode,氧化鋅直徑約為80奈米長度約15~40微米,但是直立性相當不好,大多都為捲曲的線狀。 室溫PL的量測結果發現氧化鋅奈米線在氮化鎵基板、矽基板、矽基板上鍍5奈米的金薄膜的主要螢光訊號分別為381、389、387奈米。從Photoluminescence量測結果得知,以氮化鎵作為基板成長的氧化鋅奈米線,其綠光強度相較於氧化鋅的近帶隙發光(near band edge. emission)小了0.0075倍;在矽基板上為0.01倍;在矽基板上金薄膜為催化劑為0.08倍。一般認為綠光形成原因主要是因為氧缺陷所照成的,。因此氧化鋅奈米線成長在氮化鎵基板上的氧缺陷最小。一般來說近帶隙發光(near band edge. emission)的半高寬(FWHM)越小結晶品質越好。我們可以發現氧化鋅奈米線成長在氮化鎵基板上的結晶品質最好(14.2nm),在矽基板上和在矽基板上金薄膜為催化劑的結晶品質差異不大(16nm,15.9nm)。在氮化鎵基板上成長的氧化鋅奈米線其結晶品質最好。 使用擴散方式銪元素參雜到氧化鋅奈米線上我們並未發現銪元素取代鋅原子或氧原子,而是像雜質一般形成缺陷。原本氧化鋅奈米線在325奈米雷射激發下會發出峰值506奈米、半高寬為78.3奈米的綠光,在使用擴散方式參雜銪元素後發出峰值515奈米、半高寬為125.5奈米的橙色光。從光致螢光發光(Photoluminescence)量測觀測到Donor-Acceptor Transitions,證明銪元素和氧化鋅奈米線有庫倫力交互作用。 直接參雜方式:我們利用電子束蒸鍍法在矽晶圓上鍍上5奈米的金薄膜作為催化劑,再將0.5克的鋅顆粒和0.1克的銪在950度高溫下蒸鍍到矽基板上。在將此基板已CVD方式成長氧化鋅,設定成長溫度為950度時,在基板上成長出來的氧化鋅直徑約為80奈米。使用直接參雜方式參雜銪元素在光致螢光發光(Photoluminescence)量測結果顯示578、615奈米波長有新的peak,這是三價銪離子內層電子躍遷所放出的螢光(5D0 → 7F0,5D0 → 7F3)。 In this thesis,the morphology, and optical properties of theZnO nanowires grown by chemical vapor deposition (CVD) under different growth conditions were investigated with different growth condition. For ZnO nanowires grown on Si (100), the growth mode is Volmer-Weber mode (VW-mode) due to the large lattice misfit (>30%) between ZnO and substrate. In the process of growth, the furnace was heated up to 950oC by flowing Ar with a flow rate of 100 sccm. From SEM images show that the diameter of nanowires were about 100nm. The length of nanowires were about 15 micrometer. The ZnO nanowires were grown by chemical vapor deposition(CVD) on Si substrate with employing Au as catalyst , the growth mode is vapor-liquid-solid (VLS) method . PL spectrum of ZnO nanowires grown with Au catalyst exhibits a strong defect-related deep-level emission. The ZnO nanowires grown on GaN template were vertically well-aligned with 0.5-μm-thick wetting layer. Thus, the growth mode is attributed to Stranski – Krastanow mode. The ZnO nanowires grown on the GaN template have preferred growth orientation along the c-axis. From SEM images show that the diameter of nanowires were about 100nm. The length of nanowires were about 10 micrometer. ZnO nanowires diffused with europium (Eu) are studied. The ZnO nanowires were grown by chemical vapor deposition(CVD) on Si substrate with employing Au as catalyst. Photoluminescence spectra of as-grown and Eu-diffused ZnO nanowires excited by a He-Cd laser at room temperature exhibit near-band-edge emission and green luminescence. In this work, the relative intensity of band gap and defect emission (green light) changes drastically in Eu:ZnO and ZnO nanostructures. Our results suggest that the rare earth most likely affects
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