過渡金屬二硫族化物(Transition-metal Dichalcogenides, TMDCs)為一種二維材料的統稱，是元素週期表上部分過渡金屬與硫族元素排列組合而形成的材料，如：二硒化鎢(WSe2)與二硫化鉬(MoS2)等等。他們具有半導體特性、原子級厚度、適當直接能隙、高穿透與可撓性等優點，在光學及電學特性上皆有優異表現。
以往製備TMDCs最普遍的做法為機械剝離法，雖可快速取得材料但在層數與位置上卻難以控制，增加製作元件的難度，因此本論文選擇以化學氣相沉積製備具半導體特性的二硒化鎢，對於材料層數、沉積位置以及品質有良好的控制。另外本實驗也開發出新穎技術低溫光學剝離法能夠精準控制逐層剝離二維材料，在未來可運用此技術達到快速且潔淨的大面積圖紋化製備。最後我們也針對二硒化鎢的電學及光電特性做討論，將二硒化鎢製作成背閘極結構場效電晶體並檢測其電性，之後以514 nm Ar+雷射光源照射二硒化鎢並觀察光電效應。在電性結果我們得到了場效載子遷移率為6 cm2/V‧s，次臨界擺幅為203 mV/dec；光電方面則是對514 nm光源有2.88 mAW-1的光響應。

Transition-metal Dichalcogenides (TMDCs) collectively name a series of two - dimensional materials, composed of transition metal groups and chalcogenides in the periodic table; one of such materials are: tungsten diselenide (WSe2), molybdenum disulfide (MoS2). These materials have semiconducting properties, have shown atomic-scale thickness, direct band gap, high transmittance and flexibility, etc. Besides these properties, TMDCs have shown outstanding performance in both electrical and optical fields of study.
In the past, the most popular way to synthesize TMDCs was to mechanically exfoliate each material. This method provides the least time to get material but at the cost of hard to control thickness and location for the targeted material, thus proving difficult for device fabrication. In view of this, in this work we have decided to use a Chemical Vapor Deposition (CVD) system to synthesize semiconducting WSe2 so that thickness, deposition locations, and quality are adequately controlled. In addition, we have also developed a new low temperature Optical Ablation Method that can precisely ablate 2D materials layer by layer; as such we can adopt this method to achieve clean and fast lithography for larger areas. Last but not least, we will focus on the electrical and optical characteristics of WSe2, by fabricating it into a back-gate structure field-effect transistor and measuring its electrical properties, using a 514 nm wavelength Ar$^+$ laser as source to irradiate the device channel and observe its photoelectrical response, obtaining a photoresponsivity up to 2.88 mAW-1. From the results of electrical measurements, a mobility of up to 6 cm2/V‧s, and subthreshold swing is 203 mV/dec.

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