Multiwalled carbon nanotube field emitter as an electron source for a microcolumn

Abstract

A multiwalled carbon nanotube (MWCNT) field emitter is developed as the electron source for a microcolumn-based field-emission scanning electron microscope (SEM). A MWCNT is first attached onto a tungsten (W) support tip using the nanomanipulator in the SEM. Then, an electrical bias is applied between the MWCNT field emitter and W tip to improve the contact between them, which lowers the threshold voltage for field emission. An emission current stability test showed that the emission current is stable. The fabricated MWCNT emitter exhibits a high emission current of 12 μA and sample current of around 2 nA, even at a low tip bias of 350 V in the microcolumn. The tip bias is much lower, and the sample current is higher than the equivalent values reported for W tips. The authors acquired images of a 1000-mesh copper grid using the microcolumn-based SEM with a MWCNT field emitter as the source. Our results suggest that MWCNTs should be considered a promising candidate as an electron source for microcolumns.