大面積石墨烯成長行為與機制探討

Abstract

本研究成功找到成長石墨烯最佳化的成長條件，並對石墨烯成長機制進行的一系列的探討，最後針對實驗系統進行改良，做到穩定控制成長石墨烯及石墨。 本實驗使用新式的化學氣相沉積法，以迴旋油墊幫浦的油氣回流作為碳源，不通氫氣與烷類氣體，在真空度3 mTorr的情況下在銅箔基板生長出不同層數的石墨烯。透過改變成長溫度、成長時間、不同厚度的銅基板找出可控制成長石墨烯的條件；接下來透過實驗去知道這實驗系統生長石墨烯的機制，在800 ℃時油氣開始裂解成碳沉積在基板表面，到1050 ℃時開始重新排列，在持溫30分鐘的過程中，碳融到銅箔內部，同時銅蒸氣帶走多餘的碳，使石墨烯變薄；最後依據成長行為改善實驗系統，成功藉由控制成長溫度穩定成長出石墨烯及石墨，同時也降低了成長石墨烯的溫度。 另一方面，使用乙醇或新油當碳源，在1050 ℃下成長出單層的石墨烯，在1000℃下長出多層石墨烯。由霍爾效應量測得到單層石墨烯的電子遷移力為573 cm2/Vs，品質可以跟CVD做比較。多層石墨烯的電子遷移力為244 cm2/Vs，這說明成功在1000 ℃下長出有電性的多層石墨烯；另外使用真空油43D作為碳源，成功在1000 ℃長出少數層石墨烯，均勻度63 %，說明成功在1000 ℃可長出石墨烯，然而改善均勻度和電子遷移力是仍需繼續研究的目標。

In this study, it has successfully found the optimal conditions to grow graphene and graphite, and made a series of discussion for growth mechanism of graphene. Finally, the experimental system was improve and controlled grow graphene and graphite. This study presents a CVD method using oil back streaming from the oil seal rotary vane pump as carbon source to prepare different numbers of graphene layers in on copper foil without hydrogen and hydrocarbon gas flow. Next, the optimal conditions to grow graphene and graphite by changing temperature, growth time, and different thickness of the copper substrate were obtained. Then, the mechanism of graphene by experience was also investigated. At 800 ℃, oil vapor begin to decompose the carbon source and deposited on the substrate surface. Carbon rearrange at 1050 ℃. During the holding temperature time, the carbon melt inside a copper foil, and copper vapor take away carbon, the grapheme become thinner than before. Finally, the experimental system based on the mechanism of graphene is improved. The experimental system was improved and well controlled on growth of graphene and graphite by changing growth temperature but also reduce the temperature of the growth graphene. As using alcohol or new oil as the carbon source, the single-layer graphene and multi-layer graphene can be prepared at 1050 ℃ and 1000 ℃, respectively. From Hall effect measurement, mobility of graphene reached 573 cm2/Vs and it is comparable to the mobility of typical CVD-graphene (526 cm2/Vs). Electron mobility of multi-layer graphene is 244 cm2/Vs. This shows that we have successfully grown multi-layer graphene with mobility at 1000 ℃.On the other hand, few-layer graphene can be obtained by using vacuum oil 43D as a carbon source at 1000 ℃ which graphene had a uniformity of 63 %. This shows that we have successfully grow few-layer graphene at 1000 ℃, however improvement of the uniformity and electron mobility are the goal that we need to continue to research.