穩定雙重點狀離子/電子源之製造與發射性質研究

Fabrication and Emission Properties of Stable Dual Ion/Electron Point Sources

謝文斌(Wen-Pin Hsieh)

指導教授 ： 王玉麟

國立臺灣大學/理學院/物理研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01681

摘要

我們利用銦鉍合金可製造出一種穩定的雙重點狀離子／電子發射源。把銦鉍合金作為液態金屬離子源時，低熔點的特性使他跟商業化的產品-鎵離子源一樣擁有非常好的離子發射性質。在離子源冷卻凝固之後，我們用場發射電子顯微術去研究其電子發射特性。我們也證明利用電化學蝕刻鎢針，可以改進銦鉍合金的電子發射性質，使它能跟目前所發現到具有最好電子發射特性的金銦合金離子／電子發射源之性質相接近。而在研究強電子發射與發射源表面形貌之間的關係時，我們也觀察到一個有趣的現象﹕鎢針鍍上銦之後，在長時間強電子發射下，原本堅固的鎢金屬會產生原子遷移。而這個遷移傾向於形成一個穩定的特殊幾何結構。我們發現鍍上銦的鎢針在經過這樣的過程之後，可以被用作一個擁有非常好電子發射特性的雙重點狀離子／電子發射源。對於未來更進一步發展單軸聚焦離子／電子束系統來說，銦鉍合金離子／電子發射源的發展以及適當地調控發射源，都是重要的突破。

關鍵字

離子/電子源

並列摘要

We fabricate a stable dual ion/electron point source based on In-Bi alloy. As a liquid metal ion source (LMIS), its emission performance at about 70 – 100℃ is comparable to that of commercial Ga-LMIS. After the In-Bi source is solidified, field electron microscopy is employed to study the pattern of electron emission. In-Bi alloy is inherently soft so that its electron emission is easy to be unstable. To remedy this disadvantage, the In-Bi alloy is loaded onto a sharp tungsten tip fabricated by electrochemical etching. The resulting source exhibits electron emission characteristics comparable to that of Au-In alloy.
We also investigate the correlation between surface morphology of an In/W emitter and its electron emission behavior and observe that, after long-term electron emission, some underlying W migrates to the surface. We attribute the tungsten migration to high electron emission current density. Interestingly, the migration leads to a protrusion with specific geometry on the apex of tip and such an In/W emitter constitutes a dual ion/electron emitter with good electron emission properties. Furthermore, stable ion and electron emission can be interchangeably extracted from the source. Both the successful fabrication of the In-Bi/W and In/W stable dual ion/electron point sources are important steps towards the further development of single-column focused ion/electron beam systems.

並列關鍵字

dual ion/electron point sources

參考文獻

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