運用電子束微影技術製作二維材料電晶體及其元件特性之探討

2D Material Transistors Fabricated by Using Electron Beam Lithography and Their Device Performances

唐瑞澤(Jui-Tse Tang)

指導教授 ： 吳肇欣

共同指導教授 ： 林時彥

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801125

摘要

在此論文中，我們透過預濺鍍過渡金屬再硫化的方式，成長出大面積的二硫化鉬及二硫化鎢薄膜，我們同時藉由控制濺鍍秒數進行精準的層數控制，且可利用氧電漿原子層蝕刻技術精確判斷及確認層數。利用相同的成長方法，我們先成長二硫化鎢於藍寶石基板上，接著再成長二硫化鉬於二硫化鎢上，可得到垂直結構的二維材料異質結構。因為異質接面促使能帶結構從原本的二硫化鉬變至 Type-II 二硫化鉬/二硫化鎢異質結構，我們可從光激螢光光譜中分辨出，這個轉變使得原本單一二硫化鉬的發光在量測中消失。若利用電子束微影技術及反應式離子蝕刻先將二氧化鎢進行柵欄狀圖形蝕刻，接著轉印二硫化鉬至二硫化鎢上，便可得到單一二維材料、Type-II 平面交錯形成的異質接面。將二硫化鎢、二硫化鉬、二硫化鉬/二硫化鎢及二硫化鉬/圖形化之二硫化鎢，分別製作成上閘極場效電晶體，發現二硫化鉬/圖形化之二硫化鎢之元件特性顯著高於單一材料或二硫化鉬/二硫化鎢製成之元件。由此可看出，運用二維材料堆疊異質結構，可以提升單一二維材料的元件電特性，進而可推動二維材料在電子元件上的實際應用。

關鍵字

二維材料 ； 異質結構 ； 電子束微影 ； 原子層蝕刻 ； 上閘極場效電晶體

並列摘要

In this thesis, we have demonstrated that large-area 2-D material films such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) can be prepared by the predeposited transition metal sulfurization. Good layer number controllability can be achieved by controlling the sputtering times. The actual layer numbers of the 2D materials can also be verified precisely by using the low-power oxygen plasma to perform the atomic layer etching. By using the same growth method, the vertical WS2/MoS2 2D material hetero-structure can be established on the sapphire substrate by sequentially sulfurizing pre-deposited W and Mo films. Since the band alignment would change to type-II for standalone MoS2 and WS2/MoS2 hetero-structure, the luminescence peak of MoS2 would disappear for the WS2/MoS2 hetero-structure from the photoluminescence measurement. By pre-patterning the WS2 film before the transferring procedure using the electron beam lithography, a planar hetero-structures with adjacent standalone MoS2 and type-II MoS2/WS2 can be obtained after a mono-layer MoS2 film is transferred to the patterned WS2 film. We applied these three types of thin films to the field effect transistor, including MoS2, MoS2/WS2, MoS2/pre-patterned WS2. The results shows that the transistor made from the MoS2/pre-patterned WS2 film has better performances in mobility and drain current in IDS-VGS chart than other two kinds of transistors in this experiment. Ultimately, we can conclude that heterostructure-applying transistors have overcome the limit for devices based on standalone 2D materials. The demonstration of transistor applications for 2D material hetero-structures is advantageous for the practical application of 2D materials in electronic devices.

並列關鍵字

2D materials ； hetero-structures ； atomic layer etching ； Electron Beam Lithography ； Top-gated Field effect transistor

參考文獻

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