過渡金屬硫化物之成長最佳化及其元件應用

Growth Optimization of Transition Metal Dichalcogenides and Their Device Applications

黃弘慶(Hon-Chin Huang)

指導教授 ： 吳肇欣

共同指導教授 ： 林時彥(Shih-Yen Lin)

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202001094

摘要

在本論文中，我們使用射頻濺鍍系統預鍍過渡金屬再硫化的方式製備大面積的二硫化鉬、二硫化鎢薄膜，經由控制成長溫度、壓力、時間…等條件，得到最佳的硫化參數，接著我們使用共鍍鉬和鎢金屬再硫化的方式成長出二硫化鉬-二硫化鎢合金薄膜，並且藉由控制靶材的功率達到能隙可控之不同比例的合金薄膜。除此之外，我們透過原子層蝕刻判斷二硫化鉬與二硫化鎢薄膜層數，製作出不同層數二硫化鉬、二硫化鎢和二硫化鎢/二硫化鉬異質結構上閘極場效電晶體，最後提出逐層硫化方式成功改善元件特性。之後我們使用相同方式成長二硫化鉬於石墨烯上，並將其轉印至鍍好電極的二氧化矽/矽基板後，製作出二硫化鉬/石墨烯異質結構背閘極光電晶體，當光被二硫化鉬所吸收後，產生的光電子會注入石墨烯並形成類似n型摻雜的現象而造成狄拉克點的位移，利用此特性我們可以將其作為光偵測器應用，但我們發現濺鍍鉬的過程會對石墨烯造成破壞並降低元件的載子遷移率，於是我們改使用熱蒸鍍三氧化鉬的方式取代濺鍍鉬來進行石墨烯上二硫化鉬的成長，最後成功地在不影響石墨烯的特性下製作出二硫化鉬/石墨烯背閘極光電晶體，此外我們也利用此方法在石墨烯上成長不同層數的二硫化鉬薄膜作為保護層，並大幅改善了石墨烯上閘極電晶體的特性。

關鍵字

二維材料 ； 合金薄膜 ； 異質結構 ； 上閘極場效電晶體 ； 光偵測器

並列摘要

In this thesis, we have demonstrated that larger-area molybdenum disulfide (MoS2) and tungsten disulfide (WS2) films can be prepared by sulfurizing the RF sputtering pre-deposited transition metal films. Through tuning the growth temperature, pressure, time, etc., the optimized growth parameters are obtained. Furthermore, we have demonstrated that alloy thin film can be prepared by sulfurizing the co-sputtering molybdenum and tungsten films. The alloy thin films with controllable bandgap values are achieve by controlling the sputtering powers of W and Mo targets to obtain different proportions. In addition, we have fabricated top-gate field transistors with different layers of MoS2 and WS2. The layer number of films can be precise determined by atomic layer etching. By using the layer-by-layer sulfurization, and hetero-structures, different 2D material transistors are fabricated and discussed. After that, we have fabricated MoS2/graphene hetero-structure bottom-gate photo-transistors by sulfurizing pre-deposited molybdenum on graphene and transfer it to the silicon dioxide/silicon substrate with pre-patterned source/drain electrodes. The photo-excited electrons in the MoS2 layer would be attracted by the positive drain voltage and drift to the graphene channel. Therefore, the n-type optical doping to the graphene channel is obtained, which will result in Dirac point shift and use it as a photodetector. However, we found that the process of sputtering molybdenum will damage the graphene film and reduce the carrier mobility of the device. Therefore, to replace the sputtering technique, we adopted thermal evaporation thermal evaporation to deposit the molybdenum trioxide (MoO3) to grow MoS2 on graphene. Finally, we successfully fabricated MoS2/graphene hetero-structure bottom-gate photo-transistors without reducing the carrier mobility of graphene. In addition, we also deposit different thicknesses MoO3 by thermal evaporation, and grow different layers of MoS2 films on graphene as protective layers, which greatly improves the carrier mobility of graphene top-gate transistors.

並列關鍵字

2D Materials ； Alloy thin film ； Hetero-structures ； Top-gate field effect transistor ； Photodetector

參考文獻

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