利用常壓化學氣相沈積儀橫向成長單壁奈米碳管之研究

Abstract

本論文主要是研究如何以常壓熱裂解化學氣相沈積的方式來合成單壁奈米碳管，並研究以前處理的方式，來改善單壁奈米碳管的品質，藉以得到最佳橫向成長條件。實驗設計上，預先在二氧化矽晶圓上塗佈光阻、曝光、顯影所需之圖案，之後用電子束蒸鍍(E-Beam evaporation)系統，沈積所選擇之電極種類及觸媒（catalyst）厚度，再以丙酮（acetone）剝離(lift-off)顯影之後的光阻，製程中以常壓熱裂解氣相沈積儀（Atmosphere Thermal CVD），通入所選之碳源氣體，於溫度800°C的熱燈絲製程加熱溫度下分解、擴散於觸媒中，從而形成單壁奈米碳管。 實驗中以鋁層作為緩衝層，發現鋁層在實驗的條件下，對於成長單壁奈米碳管並不如文獻中預期的發揮效用;移除了鋁層，可成功在電極鉬(Mo)上成長出單壁奈米碳管。在成長的過程前，於持溫的過程中通入氫氣來處理觸媒薄膜形成之奈米觸媒顆粒，在掃瞄電子顯微鏡（SEM）、原子力顯微鏡 (AFM)、拉曼光譜儀(Raman Spectrum) 觀察之下，發現利用前處理的方式可以改變與控制觸媒顆粒尺寸，藉以研究觸媒尺寸與單壁奈米碳管的品質之關係。 電性研究上，以下電極的方式量測，由I-V圖呈現線性的關係，可得知此實驗參數所成長出的單壁奈米碳管具金屬性的性質，此外單壁奈米碳管與鉬金屬電極材料，具良好的界面性質，相信能提供未來運用在合成單壁奈米碳管元件的製程整合。

In this thesis, we report technique for growth of singled-wall carbon nanotubes (SWCNTs) by atmosphere thermal chemical vapor deposition (AT-CVD) and used hydrogen pretreatment method to optimize parameters for high quality SWCNTs in our experiment. We used lithography technique to define our pattern on silicon dioxide wafer, then we deposited electrode and catalyst by electron beam evaporation system. The patterned electrodes were obtained using a lift-off process by dissolving the resist in acetone. SWCNT growth was made in quartz tube furnaces at 800°C and employing ethylene as the carbon feedstock. It was found that the Al buffer layer in our experimental condition can not increase the number of SWCNT. However, when Mo buffer layer was used instead of Al buffer layer, SWCNTs were grown on the Molybdenum buffer layer. We changed different pretreatment time and hydrogen gas flow to clarify the relationship between size of nano catalyst particles and hydrogen concentration. We used scanning electron microscopy (SEM), Raman spectrum, and atomic force microscopy (AFM) to confirm that pretreatment can adjust the nano catalyst particles size as a result improve the SWCNT quality. Finally, the linear I-V curve was demonstrated for the was metallic properties of SWCNT in our experimental condition.