Scanning electron imaging with vertically aligned carbon nanotube (CNT) based cold cathode electron beam (C-beam)

Abstract

A novel cold cathode electron beam based on carbon nanotube (CNT) as an electron source has been developed. The direct grown emitters fabricated as electron source have a huge potential for an electron microscope. An electron sources for high-resolution imaging requires some important parameters such as probe size, emission current, convergence angle, and beam brightness. These parameters influence the performance of an electron microscope, which in turn is heavily is dependent on the electron emission source.In the present work, direct growth CNT, a method of fabrication of emitter as an electron source for high-resolution imaging was studied. This CNT field emitters which has a spherical emitter tip as grown on Si substrate has superior hardness. A direct grown CNT emitter can draw a few micro-amperes of current. The single-CNT emitter shows 9.26 × 1010 A sr−1 m−2 V−1 of reduced brightness at 1.1 μA of emission current and a 10 μm of beam spot diameter on phosphor screen in a diode configuration. These results can be confirmed by SOURCE 2D simulation and also, the electron beam trajectory could be predicted. Finally, we fabricated an optimized electron beam module with CNT cold cathode and measured secondary electron imaging of copper grid mesh with the beam.