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標題: | 以熱敏式微影技術開發單分子裝置製作方法 Fabrication of CNT-Based Molecular Devices by Thermal Scanning Probe Lithography |
作者: | Yu-Hsiang Tseng 曾裕翔 |
指導教授: | 陳俊顯 |
關鍵字: | 熱敏式微影技術,碳管電極,單分子裝置, thermal scanning probe lithography,CNT-based electrode,molecular device, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 在分子電性的領域中,掃描式探針顯微術破裂接合法(STM-BJ)能夠產生大量實驗數據作統計分析,被廣泛應用在單分子電性的量測,也為單分子層級的物理化學現象,提供了一個強大的研究管道,但礙於此技術無法形成長時間穩定的分子接合點,使得它不能用來製作真正的分子元件。如何製作出穩固的單分子元件成為此領域的一大考驗,製作單分子元件的技術門檻在於如何形成與分子尺寸相符的電極間隙,目前分子元件主流的製作方式多屬於由上而下的方法,先製作出金屬電極間隙,再使分子跨接其中,形成「金屬電極-目標分子-金屬電極」(metal-molecule-metal, MMM),如機械破裂接合法、電遷徙法。以由上而下方法製作出的電極間隙大小難以調控,目標分子的尺寸未必與間隙吻合,使得分子接合率很低;此外,由於金屬電極與分子是透過化學吸附連接,接合強度不足,容易造成分子脫附;形成接合點時,電極上的金屬原子亦可能移動,這些因素都會使得分子接合點的結構並非穩定不變,影響分子電性的測量。為解決分子尺寸與電極間隙不匹配的問題,並形成穩定的分子-電極鍵結,本研究選用奈米碳管作為電極材料,以由下而上的方式製作分子元件。藉由偶聯劑如EDC/NHS,催化醯胺化反應,將管壁末端帶有羧酸基的碳管與首尾皆為胺基的分子進行接合,使碳管與胺分子之間形成穩定的醯胺共價鍵,於晶片表面先建構出「碳管-目標分子-碳管」,再透過熱敏式掃描探針微影技術,製作鉑奈米電極,使碳管與外部電路導通,組成「鉑電極-碳管-目標分子-碳管-鉑電極」(Pt-CNT-molecule-CNT-Pt)。本論文以開發新型態的單分子元件製作方法為目標,提供了系統性的討論,內容包含雙光阻製程的優化以提升元件製作良率、金屬型奈米碳管電性之研究、分子接合點之形成,為往後單分子電晶體的製作打下基礎。 In the field of molecular electronics, the STM-BJ is the most popular technique for creating single-molecule junctions. However, molecular junctions formed by the STM-BJ are not stable for a long time, impeding detailed studies of electrical transport and practical applications. Therefore, a new methodology for fabricating robust molecular devices is urgently needed. One of main challenges in fabricating molecular devices is to build the electrode gap that can accommodate the specific molecule. Most approaches for constructing molecular junctions are based on top-down fabrication strategies, such as MCBJs and electromigration. In the top-down fabricated devices, nanogaps are firstly constructed and then the target molecules are introduced into the nanogaps to form metal-molecule-metal junctions. Nonetheless, it is difficult to control the nanogaps to match the size of molecules by top-down methods, thus leading to low connection yield in molecular junctions. In addition, electron transport through molecules will be affected by the contact between the molecules and the metal surface. Therefore, the ill-defined bonding between molecules and metallic electrodes will lead to a large variability in the electrical properties of molecules. To solve the problem mentioned above, we construct molecular junctions employing carbon nanotubes as electrodes by the bottom-up method. Through EDC/NHS coupling, carbon nanotubes are covalently attached to amine molecules by amide linkages, forming CNT-molecule-CNT junctions on the surface of the substrate. After that, we use thermally scanning probe lithography to fabricate nanoelectrodes that aim at connecting the carbon nanotube to the pre-fabricated electrode. Finally, the molecular junction, Pt-CNT-molecule-CNT-Pt, is obtained. In this study, we focus on developing a new methodology for building molecular junctions and provide more insight into the bilayer lift-off in t-SPL and electrical properties of metallic carbon nanotubes. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/62072 |
DOI: | 10.6342/NTU202000986 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學系 |
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