Comparative study on atomically heterogeneous surface with conical arrays of field emitters generated using plasma based low-energy ion beams

A comparative study of the field emission properties of conical arrays of atomically heterogeneous, self-organized, micro–submicro–nanodimensional structures, irradiated at normal incidence by high flux of 2 keV argon ( flux = 6.47 × 10 15 cm − 2 s − 1) and krypton ions ( flux = 4.81 × 10 15 cm − 2 s − 1) on copper substrates, without employing any external seeding, is presented. The variation in surface structural growths with ion beam fluence is investigated using scanning electron, atomic force, and transmission electron microscopy. The exposed surfaces are atomically heterogeneous due to the presence of embedded argon and krypton ions in the interstitial layers ( ≈nm) as observed from the x-ray photoelectron spectroscopy analysis. Kelvin probe force microscopy is employed to analyze the variation in local work function caused by surface deformities and implantation of inert gaseous ions. The conical arrays are naturally selected field emitter sources, and their field enhancement factor is calculated from the Fowler–Nordheim equations. The argon ion treated substrate at a fluence of 4.85 × 10 18 cm − 2 gives rise to uniformly distributed structures and has a low turn-on voltage of 2.76 kV with an electron emission current of 0.58 nA. Among the krypton ion irradiated substrates, the sample irradiated at the highest fluence of 5.12 × 10 18 cm − 2 produces self-organized conical arrays having uniform dimension, orientation, distribution, and even a higher electron emission current of 0.81 nA with a lower turn-on voltage of 2.12 kV. Thus, it may be concluded that krypton ion irradiation provides better generation of naturally selected arrays of field emitters.