State of Upright Metal-Coated Carbon Nanotwists Treated by Dielectric Barrier Discharge

We have used carbon nanotwists (CNTws) as a base material of field emitter (FE), and CNTws were treated with dielectric barrier discharge (DBD) to make CNTws stand up on substrate [1]. In this study, we coated metal on the surface of FE [2] and then treated the FE with DBD. FE was prepared by screen-printing of the CNTw paste to Si or indium-tin-oxide (ITO) substrate. Cu or Pt film was coated on the FE surface by an ion coater, and Al film coated by vacuum evaporation. A thickness was 10 nm. The experimental conditions for the DBD treatment were as follows: discharge gas, N$_{2}$; gas flow rate, 2 L/min; discharge output power, 300 W; process time, 30 s; and gap distance, 0.75 mm. Lengths of upright CNTws ($L_{CNTw})$ between dots with Al, Cu, and Pt were 2.7 $\mu $m, 6.9 $\mu $m, and 8.1 $\mu $m, respectively. $L_{CNTw}$ on the dot with Al, Cu, and Pt coatings were 2.4 $\mu $m, 2.3 $\mu $m, and 1.7 $\mu $m, respectively. The FE characteristics of the CNTw coated with Cu film were as follows: the threshold electric field, 2.4 V/$\mu $m; the emission current density at 9 V/$\mu $m, 555.8 $\mu $A/cm$^{2}$. \\[0pt] [1] Y. Hosokawa, et al., \textit{J. Phys. D: Appl. Phys.}, \textbf{41}, 205418, 2008 \\[0pt] [2] Whikun Yi, et al., \textit{Adv. Mater.,} \textbf{14}, 1464, 2004