- 學位論文
利用掃描式穿隧顯微鏡研究間二碘苯在銅(100)表面生成石墨烯的行為
Scanning tunneling microscopy study of the graphene growth from 1,3-diidobenzene on Cu(100)
摘要
石墨烯是目前已知強度最強的材料，載子遷移率極高，獨特性質使其受到廣泛的研究。在導體或半導體表面上進行化學氣相沉積(CVD)可使分子大範圍在表面上生長，透過參數控制更可精準控制製備的分子層數。先前已有科學家研究出使用甲烷在1400 K下以CVD方式蒸鍍至銅箔上可生成數公分尺寸的高品質石墨烯；然而此高溫在工業製程中常遇到瓶頸，因此目前科學家致力尋找可在較低溫生成石墨烯的其它表面或分子。本實驗在超高真空 (UHV) 環境下進行，嘗試將前趨物改用間二碘苯，並分別於室溫和不同高溫的單晶銅(100)上進行蒸鍍、退火以生成石墨烯，本篇論文主要以掃描式穿隧電子顯微鏡(STM)觀測間二碘苯蒸鍍至不同溫度的銅(100)後其結構的變化。 由STM結果得知，室溫蒸鍍間二碘苯再將表面退火至880 K後觀測到其脫去氫形成芳香環結構，退火至970 K則產生0.6 nm大小之碳簇結構，至1080 K時仍未觀測到石墨烯；直接於約1000 K表面蒸鍍可得到1.2 nm 大小的奈米碳簇結構，再升溫至約1050 K，STM影像的亮點尺寸為0.5nm，推測為原先奈米碳簇結構因加熱彼此鍵結形成石墨烯奈米帶，因此STM觀測到更細微的結構，此結果說明表面開始有極小面積的石墨烯開始生成。蒸鍍間二碘苯於約1080 K表面即可在STM中觀測到石墨烯，表面上亮點轉為石墨烯的三軸向排列，並以其尺寸約0.4至0.5 nm和形貌判斷為石墨烯在銅(100)上20°之疊紋；此時另可觀測到在表面上會隨掃描發生形狀和位置改變的多層結構。
並列摘要
Graphene has been studied widely for its unique property. Processing chemical vapor deposition allows molecules growth on the surface with a wide range. Scientists had inventing a way to prepare high quality graphene with CVD by dosing methane on the 1400 K copper foils. However, the high temperature makes industrial processing much more difficult; therefore searching precursors that can produce graphene at a lower temperature becomes an imperative task. In this experiment, we choose 1,3-diidobenzene as the carbon source and then dose on Cu(100) surface in a ultra-high vacuum system and use scanning tunneling microscopy to observe the nano-structure of 1,3-diidobenzene growing to graphene. After dosing at 1000 K surface, we found nanocarbon clusters in STM images that have size about 1.2 nm. Then anneal Cu(100) to about 1050 K, the 1.2 nm nanocarbon clusters in the prior STM images disappear, instead of 0.5 nm spots align at the under copper vector. The clusters reducing size can be explained to the 1.2 nm nanocarbon clusters gathering after anneal and growing to graphene nanoribbon, making the images present the detail structure. The graphene has been detected after dosing 1,3-diidobenzene on the 1080 K Cu(100), the STM images shows three axis of graphene and the size of the spots are 0.4~0.5 nm, which is agree to the graphene 20°moire pattern with respect to Cu(100) cell vector. There are also some multi-layers of carbon cluster that changing shape when scanning been observed.