近年來，因元件的尺寸限縮，產生的種種效應，例如漏電流、閘極對通道控
制困難以及短通道效應致使半導體世界中的摩爾定律遇到了瓶頸。為此，科學家
發現並發展二維材料，其中過渡金屬硫屬化物(TMDCs)強調非凡的薄度，例如二
硫化鉬 (MoS2)的單層厚度僅有6.5Å，有別於石墨烯的零能隙，其擁有1.8 eV 的
直接能隙，以及擁有適當的載子遷移率，因此十分適合作為電晶體通道的材料。
單層TMDC 可透過機械剝離法獲得，但是這樣的方式不易獲得大面積單層MoS2，
因此需發展出可用於大面積生產的化學氣相沉積方法(CVD)。化學氣相沉積合成
的MoS2 需要使溫度上升至850⁰C，此高溫會導致背柵電晶體氧化層因底層的p+
因高溫加速擴散，而失去絕緣的功能產生漏電，因此轉移過程在背柵電晶體中扮
演著不可或缺的角色。本研究主要聚焦在轉移過程中所使用的溶液，經此方法轉
移之MoS2 不易產生皺摺或者破裂，且此改善之轉移方式幾乎適用於所有氧化層。

Recently, along with a miniaturization of devices, Moore’s law in the
semiconductor world has encountered obstacles such as leakage current, gate control
difficulties and short channel effects. Two-dimensional materials, including transition
metal dichalcogenide (TMDCs), emphasize the extraordinary thinness. For example,
the single layer thickness of MoS2 is only 6.5 Å and it possesses a direct bandgap of
1.8 eV, which is different from the zero bandgap of graphene. Besides, due to its proper
carrier mobility, it is very suitable as a transistor channel material. Single-layer TMDCs
can be obtained by mechanical exfoliation method, but it is not easy to obtain largearea
single-layer MoS2 in this method. On the other hand, a chemical vapor deposition
(CVD) method can be developed for large-area production. However, the growth
temperature of synthesizing MoS2 with CVD process needs to be raised up to 850 ⁰C.
This high temperature will lead to the recrystallization of the oxide layer of the back
gate transistor and the loss of the insulation function; and thus resulting in the current
leakage. Therefore, the transfer process plays an indispensable role in the back gate
transistor. This study focuses on the solution used in the transfer process. This research
not only shows that MoS2 is not likely to wrinkle or break after the modified transfer
method, but also proves that this simple method is applicable to almost any oxide layer.

Chapter 1...................................................................................................................................1
1-1 Research background ...................................................................................................... 1
1-2 Introduction of transistor................................................................................................. 3
1.2.1 Structure of MOSFET .............................................................................................. 3
1.2.2 Working Mechanism ................................................................................................ 4
1.3 Transistor miniaturization ............................................................................................... 7
1.3.1 Moore's Law............................................................................................................. 7
1.3.2 Short channel effects ................................................................................................ 8
1.4 2D materials .................................................................................................................. 10
1.4.1 Graphene ................................................................................................................ 10
1.5 Synthesis method of MoS2 ............................................................................................ 14
1.5.1 Traditional method ................................................................................................. 14
1.5.2 Chemical vapor deposition ..................................................................................... 15
Chapter 2.................................................................................................................................16
2.1 Motivation ..........................................................................................................................16
2.2 Fabrication process........................................................................................................ 18
2.2.1 Process flow............................................................................................................ 18
2.2.2 Chemical Vapor Deposition ................................................................................... 19
2.2.3 Transfer process...................................................................................................... 21
2.2.5 E-beam evaporation................................................................................................ 25
2.2.6 Lift off .................................................................................................................... 27
Chapter 3.................................................................................................................................28
3.1 Material characterization ............................................................................................... 28
3.2 Characteristic of wrinkle ............................................................................................... 30
3.2.1 The wrinkles appear after transfer process ............................................................. 30
3.2.2 wettability and selection of liquid .......................................................................... 31
3.2.3 Transition Electron Microscope (TEM) analysis ................................................... 35
V
3.2.4 Photoluminescence (PL) analysis........................................................................... 36
3.3 Analysis of wrinkles ...................................................................................................... 39
3.3.1 AFM analysis of wrinkle ........................................................................................ 39
3.3.2 The rate of wrinkle on MoS2 .................................................................................. 42
3.4 Electrical Characterizations........................................................................................... 43
3.4.1 ID-VG curve of different kinds of solution based transistor .................................... 43
3.4.2 The statistics of mobility ........................................................................................ 46
3.5 Characteristic of solution............................................................................................... 48
3.6 Apply on different 2D material and different substrate................................................. 49
3.7 Compare with reference ................................................................................................ 50
Chapter 4.................................................................................................................................51
4.1 Conclusion..................................................................................................................... 51
Chapter 5.................................................................................................................................52
5.1 Reference....................................................................................................................... 52

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