發展桌上型電子顯微鏡場發射式電子槍

隨著科技的進步，電子顯微鏡已經成為在物理、化學、生物、材料等各個不同領域中，不可或缺的觀測研究工具。在電子顯微鏡光源中，可分為熱游離式及場發射式二種，主要差別在於產生電子方式的不同。場發射式電子槍的針尖一般其半徑曲率為熱游離式的十分之一到百分之一倍，因此可得到更小的光源，再經過透鏡聚焦後形成極小的光斑，因此其輝度遠大於熱游離式光源。另外場發射光源和熱游離式相比頻率幾近單頻光，能量散佈較小，故在相干性的部分較佳，能夠得到較高的解析度。雖然場發射式電子槍有以上優點，但由於場發射式電子槍針尖很容易與空氣中的雜質產生反應，使得產生針尖的鈍化，影響場發射的效率，所以場發射式電子槍須要在極高的真空環境下進行運作。本研究目的，在於自行製作場發射式電子槍，取代原有的熱游離式電子槍，裝載在本實驗室設計的桌上型電子顯微鏡，提高電子顯微鏡的解析度。在本論文中我們利用電解加工的方式成功製作出場發射式電子槍針尖，其電子槍針尖曲率半徑約在100nm左右，並且其重製率也很高。最後也進行沉積氧化鋯在場發射式電子槍針尖上，完成蕭基式場發射電子槍；在經由原桌上型電子顯微鏡機台的調整、更動，完成冷、熱場發射式的電子顯微鏡的開發。

關鍵字

場發射；鎢絲；電化學；氧化鋯；蕭基式

並列摘要

With the development of technology, electron microscope has become an important observational tool in different major such as physics, chemistry, biology, and materials engineering. The source of electron microscope, it usually divide into two types, thermionic type and field emission type. Field emission type electron source usually have smaller tip radius than thermal type, so it can produce smaller electron source. Then, electron beam pass by condenser lens, a small spot size source is formed. Therefore, the brightness of the electron gun is much brighter than thermal type source. In addition, field emission source spectral energy distribution is close to monochromatic, and has smaller energy spread. So field emission source has better coherence that lead it obtain higher resolution. Although field-emission type electron gun have above advantages, but it need to maintain in high vacuum condition. Because the tip of the field emission electron gun can easily react with impurities in the air, and lead the needle tip blunt. When the needle tip is blunt, it will cause the field emission gun poor efficiency. So the field emission type electron gun needs lots of high vacuum equipment to maintain it stay in high vacuum condition and high efficiency. The purpose of this research is using cheaper and more convenient ways to produce a field emission electron gun tip. And then set it up on our lab’s group made Desktop Electron Microscope to improve the resolution. In this paper, we successfully fabricated a field electron gun tip using electrolytic machining. The radius of curvature of the electron gun tip is about 100 nm or less, and its reproduction rate is also high. Finally, we also tried to deposit ZrO on the tip to make thermionic (Schottky) type field electron gun. After that, we also design some components installed on our Desktop Electron Microscope to finish field emission microscope.

並列關鍵字

Field emission ； Tungsten ； Electrochemistry ； Zirconium oxide ； Schottky type

參考文獻

1. Schumacher, E. F., Microscopy for Materials Characterization: Illuminating Structures With Light and Electrons. AMERICAN LABORATORY 2014, 46 (7), 24-26.

Google Scholar

2. Crewe, A.; Eggenberger, D.; Wall, J.; Welter, L., Electron gun using a field emission source. Review of Scientific Instruments 1968, 39 (4), 576-583.