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    請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/80696


    題名: 氧化鋅薄膜與奈米柱的螢光光譜;Photoluminescence spectra of ZnO thin film and nanorod
    作者: 吳宣誼;Wu, Hsuan-I
    貢獻者: 物理學系
    關鍵詞: 氧化鋅;螢光;聲子;激子;能隙;缺陷;ZnO;Photoluminescence;Phonon;Exciton;Band gap;Defect
    日期: 2019-07-03
    上傳時間: 2019-09-03 14:59:45 (UTC+8)
    出版者: 國立中央大學
    摘要: 本論文藉由光激螢光光譜(PL spectra)來分析不同退火條件(無退火、600℃退火或700℃退火)的奈米柱氧化鋅樣品與不同鋅氧含量比例(晶格中鋅較多或氧較多)的薄膜氧化鋅樣品之各種特性(諸如結晶品質、激子特性、能階結構、能隙隨溫度變化特性與聲子所造成的螢光特性等等)。
      在低溫的光譜中,各樣品除了在氧化鋅能隙3.36eV波段附近有強又窄的近能隙輻射(Near band-gap emission, NBE)訊號外,低能量波段(約1.8~2.4eV)附近則也出現了寬訊號。
      低能量寬訊號主要由電子在晶格缺陷對應的能階間躍遷所產生的缺陷輻射(Defect related emission, DE)並同時耦合若干個聲子(Phonon replica)所形成。NBE對DE的強度比值可反映出樣品的結晶品質(此比值越大則晶格愈趨理想)。從低溫的光譜中可發現:奈米柱樣品經退火後會比無退火有著更大比值,退火溫度越高比值也更大;而氧含量較高的薄膜樣品則比鋅含量較高的樣品有著更大的比值。
      另外,薄膜的DE出現了由聲子耦合所形成的波浪狀起伏。鋅含量較多之薄膜樣品在3.0eV附近也出現了其他樣品所沒有的寬波浪狀訊號,這是由該樣品中特有的缺陷能階與受子能階所造成。
      從變溫PL光譜中可獲得不同溫度下各氧化鋅樣品的能隙。Manoogian–Wooley所提出的模型指出半導體的能隙隨著溫度上升而紅移的現象主要受熱膨脹與聲子作用這兩個因素影響,其中熱膨脹效應影響得越厲害則在低溫時的紅移程度便越大。經由MW模型擬合此數據,可得知奈米柱樣品的能隙不易受到此效應所影響。
    ;By using photoluminescence spectroscopy (PL), we have studied the properties (Cystal quality, Exciton properties, Energy level, Band gap energy fuction of temperature and the signal caused by the phonon) of the nanorod ZnO whose annealed condition were different (As-grown, Annealed 600℃and 700℃) and the thin film ZnO temperature whose Zn/Oxygen ratio were different(more Zn or O in the crystal).
    In the low temperature PL spectra of the all sample, it not only appeared a strong and sharp near band gap emission (NBE) signal around 3.36 eV, but also appeared a wide signal from 1.8 to 2.4 eV caused by the fact of the electron transition in the crystal defect energy level (DE) and meanwhile coulpling several phonon (Phonon replica) at the same time. The intensity ration of NBE to DE could reflect the crystal quality of the sample. From the low temperature PL spectra we found that the ratio of nanorod sample would increases as procedure annealing, and would keep increased as the annealed teprature increased; thin film sample would increases as Zn/Oxygen ratio decreased.
    Moreover, the DE of thin film appeared the “wave like” curves which caused by the influence of the phonon. The Zn-rich thin film sample also appeared the “wave like” curves that all the other sample didn’t have: this is caused by the unique defect level and acceptor level existed in that sample.
    The value of the bad gap energy of variety temperature could be found from the temperature dependent spectra. Manoogian–Wooley’s (MW) model indicated that the phenomenon of the red shift of the band gap energy of the semiconductor as temperature increased is mainly caused by thermal expansion and phonon-coupling effect. The degree of the red shift in low temperature would be more obvious if the effect of thermal expansion is hard. We finally found that the band gap energy of nanorod ZnO didn’t influence by this effect throughout the fitting of MW’s model.
    顯示於類別:[物理研究所] 博碩士論文

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