本論文中，我們使用化學氣相沉積法成長不同的二維材料，如二硒化鎢、石墨烯等等，在成長二硒化鎢時，透過控制前驅物重量、成長溫度等參數來控制二硒化鎢的成長尺寸以及疏密程度等等，最終找到一個最佳成長條件為溫度980 ℃、氧化鎢粉末0.26 g、硒錠0.43 g，接著將成長出來的二硒化鎢製備成背向閘極場效電晶體並分析其電特性。接下來透過二硫化鉬/二硒化鎢異質結構製作成電晶體，來優化二硒化鎢的電特性。我們也分析了二硫化鉬/二硒化鎢異質結構以及二硒化鎢/二硫化鉬異質結構的拉曼光譜以及光激發光光譜，並探討其光學特性的變化。另外，我們一樣使用化學氣相沉積法在石墨烯基板上成長二硒化鎢，最後透過降低成長溫度而成長出大面積且均勻的二硒化鎢薄膜。接著我們在銅箔上成長高品質的石墨烯，並製備了二硫化鉬/石墨烯以及二硒化鎢/石墨烯異質結構，將其各別製備成背向閘極場效電晶體，而當我們將單層二硫化鉬以及單層二硒化鎢作為光吸收層，石墨烯作為載子傳輸層，將兩種異質結構的元件作為光偵測器，在元件上照射不同波長的光源，並量測產生的光電流，可以發現不同材料異質結構的元件，所量測出來的光電流大小以及截止波長的位置都不相同，由此可看出薄體二為材料及其異質結構作為光偵測器應用之潛力。

In this thesis, we use chemical vapor deposition (CVD) to grow single-crystal and mono-layer tungsten diselenide (WSe2) flakes. Compared with the results obtained from samples grown at different weight of tungsten oxide powder and selenium and higher temperature, we found that the size and density of single-crystal WSe2 flakes can be controlled by the weight of precursor and the growth temperature. We found that the best growth condition is in 980 ℃ with 0.26 g of WO3 and 0.43 g of Se. The optimized WSe2 flakes is fabricated into the bottom-gate field effect transistor (FET), and analyzed its electrical properties. We used molybdenum disulfide (MoS2) as a passivation layer to protect WSe2 from the damage by lithography, and optimized the electrical properties of WSe2 bottom-gate transistor. We also investigated the optical characteristics of mono-layer MoS2/mono-layer WSe2 hetero-structures with different stacking sequences. Next, we try to grow WSe2 on graphene substrate. Finally, we obtained large-area and uniform WSe2 by lowering the growth temperature to 900 ℃. Then, we fabricated the bottom-gate transistors by using mono-layer MoS2/ mono-layer graphene and mono-layer WSe2/mono-layer graphene for photodetector applications. In this device architecture, MoS2 and WSe2 are the absorption layers and graphene is the channel material. We have observed different responsivities and cut-off wavelengths from these devices. The results have demonstrated the potential of thin-body 2D materials and their hetero-structures for photodetector applications.

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