Field emission (FE) of electrons from a multiwall carbon nanotube (MWNT) with a closed cap provides field emission microscope (FEM) images showing of bright pentagonal rings when the surface of a MWNT cap is clean. Adsorption of a gas molecule onto a clean pentagon brings about a change in the FEM images from the pentagonal ring to a bright spot with a sudden increase in emission current. In this work, aluminum (Al) was deposited on MWNT field emitters and its effects on FE properties were studied by FEM. A considerable improvement of emission stability was obtained by Al-deposition, and an atomically-resolved image of an Al cluster with face-centered structure was observed by FEM.
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