以熱蒸鍍法成長鉍奈米線之研究

Abstract

在本篇論文中，我們在高真空的腔體內利用熱蒸鍍法，藉由無催化劑的機制成長鉍奈米線。 研究主要先是透過X-光繞射(X-ray diffraction, XRD)來量測不同溫度時鉍薄膜的厚度，由此推測玻璃上鉍薄膜成長速率，之後透過掃描式電子顯微鏡(Scanning Electron Microscope, SEM)來解釋XRD圖變化的原因以及表面型態，接著研究同方法下在不同基板上的變化，包括雲母、石墨及巴克明斯特富勒烯（C60），發現單以此方法不容易長線。 由於在C60薄膜上的成果較好，因此嘗試先在低溫下鍍一層薄膜後，再於高溫下長線，成功得到多且長的鉍奈米線，其後嘗試用相同方法長於其他基板上，發現不能直接套用相同條件。 接著為了驗證成長機制的猜測，透過原子力顯微鏡（atomic force microscope, AFM）檢視基板表面情況。 最後，把成長結果較佳的基板透過接觸的方式，將奈米線移轉到測量用的基板，利用電子微影技術畫出測量電性用的電路，由此測量出不同直徑時鉍奈米線的電阻率變化。

In this study, we grew Bi nanowires through thermal evaporation and catalyst-free mechanism in the high-vacuum chamber. First, we used XRD to measure the thickness of the Bi films grown at different temperatures. From this, we can calibrate the deposition rate of Bi on glass. Then, through SEM, we can observe the morphology of the sample surface. Using the same deposition procedure on other substrates, including mica, graphite and C60, we found that this method was not effective for growing Bi nanowires. Since the result on the films of C60 was better, we tried to coat a thin film at low temperature first, and then grew nanowires at high temperature. It was successful in growing many long Bi nanowires. Then, applying the same method to other substrates, we found that it did not work well under the same conditions. Next, in order to verify the proposed growth mechanism, we used AFM to check the surface of the substrates. At last, contact transfer of the nanowires from the substrates had better result for the C60 substrates. We used electron beam lithography system to fabricate the circuit for electrical tests so we can compare the resistivity of Bi nanowires of different diameters.