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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/68425


    Title: The growth of Bi on Ag(111) studied with STM, LEED and XPS
    Authors: 游采鳳;Yu,Tsai-Feng
    Contributors: 物理學系
    Keywords: 低能量電子繞射儀;掃描穿隧顯微鏡;X光光電子能譜術;Bi;Ag(111);XPS;STM;LEED
    Date: 2015-07-20
    Issue Date: 2015-09-23 11:33:51 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本論文旨在探討鉍 (Bi) 在銀(111) 表面上室溫與低溫下不同的成長模式。研究在超高真空環境下藉由電子束加熱的方式產生鉍原子,使其吸附於銀(111) 表面上,並利用掃描穿隧顯微鏡 (Scanning Tunneling Microscopy, STM)、低能量電子繞射儀 (Low Energy Electron Diffraction, LEED) 和X光光電子能譜術 (X-ray Photoemission Spectroscopy, XPS) 來研究鉍在銀(111)表面上覆蓋量與溫度對表面形貌的影響。鉍原子在室溫下沉積,低覆蓋量時表面會形成(√3×√3)R30°表面合金 (alloy) 的重構,合金結構的產生會造成表面不平坦且有許多銀島嶼;持續增加其覆蓋量,表面結構會轉變成(n012)去合金 (de-alloy) 的重構,此時不平坦的表面卻不會因增加覆蓋量而趨於平坦。而在低溫的環境下沉積鉍原子,因鉍原子沒有足夠的動能取代表面的銀原子,與基板鍵結成合金,所形成的表面不會有銀島產生。低覆蓋量時,鉍原子直接覆蓋於表面,會產生模糊的(2×2)結構;高覆蓋量時則會形成(n012)的重構,將沉積後的樣品退火至不同溫度,接著透過X光光電子能譜術量測分析Bi 4f與Ag 3d,可看出電子態隨著溫度及鍍量不同之演化。Bi 4f的化學位移可證明與合金-去合金結構轉換相關。經由掃描穿隧顯微鏡可觀察到其表面原子排列的型態。最後由實驗證明在室溫下的沉積會因合金的形成造成表面不平坦;而在低溫條件下的成長模式,經退火後能使其薄膜有平坦的表面且形成高度有序的結構。;We have studied the coverage-dependent surface morphology of Bi on Ag(111) with scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and X-ray photoelectron spectroscopy (XPS). Two surface reconstructions were identified with deposit of Bi on Ag(111) at 300K. At room temperature, a (√3×√3)R30° reconstruction was observed with a low Bi coverage, and a (n012) reconstruction emerged with further Bi deposition. The evolution of the core levels Bi 4f and Ag 3d were characterized and analyzed with varied Bi coverage. The shift in the binding energy of Bi 4f was observed; it was associated with the de-alloying process. The STM results showed that the monolayer Ag islands and pits forms randomly across the surface during the initial Bi deposition, resulting in a rough surface of Bi/Ag(111)-(n012). At low temperature, a (2×2) reconstruction was observed with a low Bi coverage, and a (n012) reconstruction emerged with further Bi deposition. The shift in the binding energy of Bi 4f was not observed. Indicating each no surface alloy forms during low temperature deposited.
    Appears in Collections:[物理研究所] 博碩士論文

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