Laser surface treatment of screen-printed carbon nanotube emitters for enhanced field emission

This paper investigates the surface treatment of screen-printed carbon nanotube (CNT) emitters using a 248 nm (KrF) excimer laser. The field emission characteristics of the CNT emitters are measured following irradiation using laser fluences ranging from 80 to 400 mJ/cm2. The results show that the turn-on electric field, the current density, and the distribution of the emission sites are highly dependent on the value of the laser fluence and are optimized at a fluence of 150 mJ/cm2. Two distinct laser fluence regimes are identified. In the low fluence regime, i.e. 80-150 mJ/cm2, the surface treatment process is dominated by a photo ablation mechanism, which results in the gradual removal of the binding material from the cathode surface and leads to an improvement in the emission characteristics of the CNT cathodes with an increasing fluence. However, in the high fluence regime, i.e. 150-400 mJ/cm2, the thermal ablation mechanism dominates; resulting in a removal of the CNTs from the cathode surface and a subsequent degradation in the emission characteristics.