本研究為探討少層液相剝離石墨烯(Graphene)的薄膜特性，以及於N型有機薄膜電晶體中加入此層Graphene薄膜的電特性影響。在薄膜特性方面，將運用原子力顯微鏡(AFM)、穿透式電子顯微鏡(TEM)與拉曼光譜等儀器，分析透過液相剝離法(liquid exfoliation)製作出的少層石墨烯；在電特性方面則是以半導體材料PTCDI-C13為主動層的元件中，比較有無加入Graphene薄膜的輸出特性曲線、轉換特性曲線、電容以及環境穩定度之變化。
首先，AFM的分析結果顯示，利用液相剝離法可成功剝離出2-4 nm厚的少層石墨烯，然而從AFM與TEM的表面形貌圖分析中，均發現少層石墨烯上方有皺褶與片狀碎片的重疊；並且應用TEM的電子繞射分析亦得到當少層石墨烯的層數較少時，其電子繞射圖形的第一階繞射強度會較強；此外，從拉曼光譜的分析還發現2D peak並非單一的勞倫茲曲線所組成，代表石墨烯層與層之間有電子相互作用力存在，這個結果驗證了本實驗所剝離之石墨烯即為少層石墨烯。
接著，從輸出及轉換特性曲線結果顯示，於N型有機薄膜電晶體中加入一層Graphene薄膜，可有效提升元件的飽和電流(IDS,sat)及載子遷移率(Mobility，μ)，推測是由於Graphene結構的π電子雲貢獻，改善元件通道中載子傳輸的路徑，使得載子傳輸時的導電性提升所導致；最後，從電容分析結果可得到，加入Graphene薄膜有助載子在低頻時的穩定累積，並且可以增加元件之電容對頻率的穩定性。總的來說，本研究成功利用加入Graphene薄膜提升N型有機薄膜電晶體的電特性。

In this thesis, the properties of the few-layered graphene produced by liquid exfoliation were analyzed by using atomic force microscope (AFM), transmission electron microscope (TEM), and Raman spectrometer. The influences of the few-layered graphene on the electrical characteristics of n-type organic thin-film transistors (OTFTs) were studied.
According to the AFM images, the few-layered graphene with thickness ranged from 2 to 4 nm was successfully produced by the method of liquid exfoliation. We observed that some wrinkles and small flakes were found on the surface of the few-layered graphene from the TEM images. Moreover, the electron diffraction patterns of the few-layered graphene indicate that the typical sixfold symmetry pattern confirms the formation of graphite/graphene. The intensity of the first-order diffraction peaks increased with decreasing the layer number of the few-layered graphene. Based on the Raman spectrum of the few-layered graphene, the 2D peaks were not composed of single Lorentzian function, indicating the existence of electronic interaction between adjacent graphene layers. This result indicated that the graphene produced by liquid exfoliation was few-layered graphene, not single-layer graphene.
Next, we applied the few-layered graphene to n-type OTFTs and studied the electrical characteristics of these devices. The results showed that the few-layered graphene improved the conductivity of conducting channel and enhanced carrier transport. Therefore, the saturated drain currents and carrier mobility of the devices with the few-layered graphene were increased. Interestingly, the capacitances of the devices with the few-layered graphene were larger than those without the few-layered graphene. Moreover, the few-layered graphene could stabilize the carrier accumulation within the devices at low frequency during capacitor measurements, indicating that an insertion of the few-layered graphene into n-type OTFTs could enhance the stability of capacitance.

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