本論文主要分成兩部分，第一部分以化學氣相沉積法(Chemical Vapor Deposition)合成大面積的單層二硫化鉬，藉由控制製程參數獲得高品質單層二硫化鉬。第二部分製備二硫化鉬之場效電晶體(FET)，藉由電性量測與光感測(Photodetection)量測，探討單層二硫化鉬之光電特性及光感測器應用，二硫化鉬之場效電晶體元件具有優異之電性：開關電流比(On off current ratio)可達104至105，載子遷移率約為12.5cm2/Vs。單層二硫化鉬具有優異的光感測特性，其場效電晶體元件照光後，光電流於7.6秒內能增加70%飽和光電流，25秒內能降低70%飽和光電流，經由計算可以得知在汲極電壓為1V且閘極電壓為10.5V下，光響應率高達392.5A/W。另外從實驗結果可以得知在大氣下的量測較能使得光電流有弛豫(Relaxation)的現象，可能的原因推測是空氣中有一些吸附物會吸附在二硫化鉬的表面，這些吸附物傾向於捕獲二硫化鉬內部的本質電子，造成表面類似p型摻雜的結果，也就是如D+e-→D-的反應式，而在照光後激發電子電洞對，其中的電洞與帶負電的吸附物進行復合(Recombination)，也就是這些吸附物在照光後有類似光脫附(Photo-desorption)的效果，寫成反應式即D-+h+→D，因此在大氣中關閉光源時，由於這些吸附物傾向於捕獲電子，產生類似協助光電流進行弛豫(Relaxation)的效果，而在照光時，這些吸附物與電洞複合進而脫附離開材料表面，反之在真空中，因為缺乏這些吸附物，在關閉光源時無法有效將光電流弛豫，所以在關閉光源時汲極電流下降的較在大氣中慢，而在打開光源時，也因為不需要提供電子電洞對復合這些帶電的吸附物，因此可以得到較高的光電流值。

In this research, we used chemical vapor deposition to synthesize large area monolayer MoS2, then we fabricated MoS2 FET and measured its electrical properties and photodetection.
MoS2 has excellent electrical properties: our device could reach 12.5 cm2/Vs mobility, 104 to 105 on/off current ratio.
In photodetection of MoS2 FET, our device took 7.6 second to reach 70% of saturation photocurrent, 25 second to decay. And under 1V drain voltage, 10.5V gate voltage, the responsivity of our device was 392.55A/W.

第一章 研究動機 1
第二章　文獻回顧 2
2-1　晶體結構 2
2-2　電子與能帶結構 2
2-3　光學特性 3
2-4　過渡金屬硫族化合物之合成 4
2-5　二硫化鉬的電性質 6
2-6　二硫化鉬的光電性質 8
第三章　實驗方法 16
3-1　實驗大綱 16
3-2　實驗準備與實驗架設 16
3-2-1　基板前處理 16
3-2-2　實驗架設與步驟 17
3-3　實驗量測及儀器 18
3-3-1　晶體結構分析 18
3-3-2　光學顯微鏡照片 18
3-3-3　表面形貌與厚度觀察 18
3-3-4　光學性質量測 19
3-3-5　表面成分分析 19
3-3-6　光感測元件電性量測 19
3-4　場效電晶體製作 21
第四章　化學氣相沉積法合成二硫化鉬 24
4-1　前言 24
4-2　不同硫量與硫坩鍋位置對成長的影響 24
4-3　材料品質與層數的鑑定 26
第五章　光電量測與光感測特性 33
5-1　二硫化鉬場效電晶體之電性量測 33
5-2　二硫化鉬場效電晶體光感測量測 36
5-2-1　不同光源比較 36
5-2-2　不同閘極與源極偏壓對形成光電流比較 37
5-2-3　真空與大氣下量測比較 38
5-2-4　縮小電極對光感測元件的影響 41
第六章 參考文獻 57

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