| 摘要: | 二硫化鉬由於良好的光電特性，如高載子遷移率、能隙可透過層數調節等，被視為擁有突破傳統半導體材料物理極限的潛能，因此人們開始對其進行大量的研究。本研究旨在研究如何低溫成長均勻的可控層數二硫化鉬薄膜，我們使用兩種製程方法，並比較成長的結果。
第一種方法為兩階段化學氣相沉積製程，先濺鍍鉬薄膜，接著利用硫粉對鉬薄膜進行硫化。第二種方法為一階段物理氣相沉積製程，直接在濺鍍鉬靶材時通入硫化氫，使鉬及硫原子產生化學反應，成長二硫化鉬薄膜。兩種實驗方法皆透過調整濺鍍時間、功率及溫度等參數，以找出最佳的製程條件。
本研究利用拉曼光譜、X射線光電子能譜儀及PL光譜，確認薄膜分子結構、元素分析及光致發光效率外，也使用拉曼區域掃描(Raman Mapping)及原子力顯微鏡，分析薄膜的均勻性及表面粗糙度。實驗結果顯示兩種製程方法皆可透過調控濺鍍時間控制層數，然而在粗糙度及均勻性方面，一步法成長的薄膜粗糙度為0.318 nm，明顯低於兩步法製程的薄膜粗糙度3.62 nm，在mapping結果也具有更好的均勻性。不僅如此，一步法在190 ℃成長的薄膜，其光致發光效率和兩步法於550 ℃成長差不多。從研究結果確認，以一步法製程能在較低溫便成長出具良好光致發光效率，且均勻的平整二硫化鉬薄膜。
;Molybdenum disulfide (MoS2) is considered to have the potential to break through the physical limits of conventional semiconductor materials due to its good optoelectronic properties, such as high carrier mobility and tunable bandgap, etc. leading people extensive research on it. This study aims to grow uniform and controllable-layer MoS2 thin films at low temperature. Two methods have been used to grow MoS2 with different results. The first method is a two-step chemical vapor deposition (CVD) process, where molybdenum (Mo) thin films are first sputtered, then sulfur powder was applied to sulfide the molybdenum films. The second method is a one-step physical vapor deposition (PVD) process, where molybdenum targets are sputtered directly with hydrogen sulfide plasma to be reacted as molybdenum disulfide. The parameters, sputtering time, power, and temperature are adjusted in both methods to determine the best processing conditions. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy have been applied to confirm the molecular structure, elemental composition, and photoluminescence efficiency of the thin films.
Raman area scanning and atomic force microscopy (AFM) have also been used to analyze the uniformity and the surface roughness of the films. The experimental results show that both methods can control the number of layers by adjusting the sputtering time. However, in terms of roughness and uniformity, the roughness of the one-step process is 0.318 nm, which is significantly lower than that the two-step process at 3.62 nm, and the mapping results also have better uniformity. Moreover, the photoluminescence efficiency of the one-step process at 190°C is similar to that the two-step process at 550°C. From the results of the study, it is confirmed that the one-step process can produce flat and uniform MoS2 thin films with good photoluminescence efficiency at lower temperatures. |
