The effect of surface treatments on the field emission characteristics of patterned carbon nanotubes on KOVAR substrate

The field emission characteristics of patterned carbon nanotubes (CNTs) the average diameter of which is 16 nm cathodes on substrates with different surface treatments were investigated. The surface treatments of the substrate were performed by nickel electroless plating and palladium coating, which is an activation procedure of electroless plating. CNTs were patterned on the surface-treated substrate with radius of 200 μm through conventional photolithography process. Two deposition methods, electrophoresis deposition and spray deposition, were used to investigate the effects of deposition methods on field emission characteristics of the cathodes. It was revealed that the two deposition methods showed similar turn-on field trends, which means that the different surface morphologies of the substrates have more influence on the field emission characteristics than the different deposition methods performed in this study. Through the surface treatments, the roughness of the surface increased and cathodes with a high roughness factor showed better field emission characteristics compared to non-treated ones.