近年來，二維層狀材料因為其獨特的物理與化學特性而廣受關注，其中，過渡金屬硫化物已經在過去幾年中被探索，並且在光電領域中展現了優異的特性。在本實驗中，我們透過化學氣相沉積法分別於二氧化矽基板上成長n型之二硒化鉬，以及於銅箔上成長石墨烯，在常壓中成長的石墨烯表面會吸附來自大氣中的水氣與氧氣，使石墨烯打開能隙並使其變為p型，再透過蝕刻轉印的方式將石墨烯從銅箔上轉移至二硒化鉬上方，形成二硒化鉬/石墨烯/二硒化鉬之npn型電晶體結構，並且得到之最佳電流增益為4.65。在實驗過程中，我們發現我們合成的電晶體結構上出現了電流增益值先大後小的趨勢以及位於5 V的較大的電晶體啟動電壓，我們分別透過半波整流結果與電流擁擠效應對其進行了解釋。並且在我們的量測分析中，我們分別於拉曼量測與X光光電子能譜儀上檢測到二硒化鉬中含有二氧化鉬的成分，證明我們目前二硒化鉬的製程上仍有硒化不完全的問題，綜合討論可以發現，我們的電晶體結構仍有許多改進空間，諸如製程方面的優化、電晶體結構改變射極與集極兩端二硒化鉬的濃度差與基極寬度縮短等，都是有待改善的。

Recently, two-dimensional layered materials have received considerable attention because of their unique physicochemical properties. Among them, transition metal dichalcogenides (TMDCs) have already been researched over the last few years and have exhibited excellent performance in both electronic and optics. In this study, molybdenum diselenide (MoSe2) and graphene were grown on the silicon dioxide (SiO2) substrate and copper foil by the chemical vapor deposition (CVD) method, respectively. It could be noticed that graphene would adsorb moisture and oxygen on its surface to open the band gap and made itself become a p-type material in our atmospheric synthesizing process. To realize the MoSe2/graphene/MoSe2 bipolar junction transistor (BJT) structure, graphene was transferred onto MoSe2 from the copper foil by the etching method. This BJT structure could demonstrate the current gain () which was 4.65. In this experiment, we used the result of current crowding effect to explain the tendency of the  value which increased at first and then decreased when the VBE voltage exceeded 8 V. On the other hand, we utilized the result of half-wave rectification to interpret the reason of turn on voltage of the transistor at 5 V. Moreover, we found that there were signals of molybdenum dioxide (MoO2) in our MoSe2 sample by the Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) measurement. It could prove that we still have the problem in our fabricating process which was uncompletely selenizing. In summary, we found that there were still many problems needed to be improved in this BJT structure, such as changing the concentration of MoSe2, reducing the proportion of MoO2 in the CVD process of MoSe2.

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