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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/68100

    Title: 藉由物理氣相沉積合成大面積且高結晶性的二硫化鉬薄膜;Large Area and High Quality MoS2 Thin Film Synthesized by Physical Vapor Deposition
    Authors: 陳幸鴻;Chen,Sing-hong
    Contributors: 化學工程與材料工程學系
    Keywords: 二硫化鉬;大面積;高結晶性;物理氣相沉積;MoS2;Large area;High quality;Physical vapor deposition
    Date: 2015-07-15
    Issue Date: 2015-09-23 10:44:26 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 由於石墨烯特別的二維結構和物理性質;例如:超高的載子遷移率,吸引了非常多人的注意,但因為沒有能帶間隙,限縮了在邏輯電路上的應用。而另一種二維材料:過鍍金屬二硫屬化物,在奈米級電子產品和光學應用上也表現出相當好的潛力,而二硫化鉬是其中一種被廣泛研究的材料。相較於石墨烯它更適合應用在高效能的電子元件上,因為它除了二維的結構外也擁有會隨的層數改變的能帶間隙。
      近年來有非常多的方法被提出來製造二硫化鉬薄膜,包括剝除法及化學氣相沉積法等,但要以這些方法製作出大面積並且連續的二硫化鉬薄膜並不容易,因此不適合大面積應用,在本論文中,我們提出了一個簡單且可擴展的兩步驟方法:先以超高真空濺鍍系統濺鍍二硫化鉬靶材在藍寶石基板上,接著藉由化學氣相沉積系統進行硫化反應,製作出不但連續且高度結晶性的二硫化鉬薄膜,也可以用濺鍍時間來控制二硫化鉬薄膜的層數,雖然受限於石英爐管的直徑只有1英吋大小,我們只能製作出4×1平方英寸大小的二硫化鉬薄膜,但如果能把爐管的直徑加大,那我們就能製作更大面積的二硫化鉬薄膜。我們也利用了許多分析來證明我們的薄膜擁有高結晶性,包括拉曼光譜分析、光激發螢光光譜分析、穿透式電子顯微鏡及X光光電子能譜儀分析,而我們製作出的雙層及多層的上閘極二硫化鉬薄膜電晶體,也具備合理的電性。透過降低硫化溫度,我們成功的改善了二硫化鉬薄膜的均勻性,也利用二次諧波產生驗證730°C是比1000°C更好的硫化溫度,而製作出來的雙層二硫化鉬薄膜電晶體的電性也大幅改善,且擁有開關比率104、次臨界擺幅873 mV/decade及載子遷移率0.0193 cm2/Vs,雖然在實現高效能的元件前還有很多問題要解決,但此研究在未來大面積二硫化鉬薄膜成長與應用奠定了良好的基礎。
    ;Graphene has attracted much attention due to its unique two dimensional structure and physical properties, such as high carrier mobility. However, the gapless nature prohibits its application of logic circuits. Other two-dimensional layered nanomaterials, transition metal dichalcogenides(TMDs), such as MoS2, also show great potential in nanoelectronics and optical applications. MoS2 is superior than graphene to fabricate high-performance devices, because of its two-dimensional structure but also possesses thickness-dependent band gap.
      Recently, several methods have been proposed to prepare MoS2 atomically thin layers, including exfoliation and chemical vapor deposition, etc. However, it is challenging for these methods to produce large area and continuous MoS2 thin films, and thus not suitable for large area electronics. In this thesis, we present a simple and scalable two-step method for MoS2 synthesis. First, we used UHV-sputter system to deposit MoS2 thin films on sapphire substrates by using a MoS2 target, followed by sulfurization in hot-wall furnace. This method produces large area and continuous MoS2 thin films, and provides excellent controllability on the number of layers of MoS2 by sputtering time. The 4×1 in2 MoS2 thin films, demonstrated in this study was limited by the quartz tube furnace with 1-inch diameter. If we increase the diameter of the quartz tube, MoS2 thin films with even larger areas can be expected. Various spectroscopic and microscopic methods, including Raman spectroscopy、photoluminescence spectroscopy、high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy confirmed that our films are high quality. We also fabricated bilayer and mutiple-layer top-gate MoS2 thin film transistors with reasonable electrical characterizations. By decreasing the temperature of sulfurization, we further improved the uniformity of our films. The bilayer MoS2 thin film transistors also show superior characteristics with on/off current ratio of 104、subthreshold swing 873 mV/decade and electron mobility of 0.0193 cm2/Vs. Although there are still various problems to be solved before realizing high-performance devices, this research serves as a starting point for future large-area MoS2 applications.
    Appears in Collections:[化學工程與材料工程研究所] 博碩士論文

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