Carbon nanotubes field emission enhancement using a laser post treatment

This paper reports the fabrication of a cold cathode based on carbon nanotubes (CNTs) using a combined chemical vapor deposition technique and a laser processing treatment. The CNTs are exposed to a focused 514 nm continuous-wave laser at varying power, and the changes of the CNTs characteristics after each laser treatment are investigated by Raman spectroscopy and scanning electron microscopy. It is seen that a laser treatment at 70 mW produces an improved emitter, characterized by an increase of the field emitted current up to 350 times, which obtains a maximum current density of 0.13 A/cm2. The CNT deposit exhibits good time stability and a good resistance under high applied electric fields up to 33 V/μm. The results obtained in terms of current density make the laser treatment an excellent process for increasing the performance of cathodes to be used in electron guns for vacuum tubes where high current densities are required.