Field emission properties of atomically heterogeneous metallic nanostructures created by microwave plasma generated low energy ion beams

The field electron emission from material surface is a well-known quantum mechanical process which has various technological applications in field-emission displays, electron microscopes, electron guns, including vacuum nanoelectronics. In 1928, approximate theoretical description of field emission from bulk material was given by Fowler Nordheim equations. With advent of modern technology, field emitter tips of radius of curvature in the sub-nanometer regime can be processed. One such example of surface processing is surface modification using low energy ion beams, where, not only porosity and emission surface area is increased due to sharp emitter like nanostructure formation, but also there is low energy ion implantation in the host metal lattice. The afore mentioned nonplanar surface emitter geometry added with atomic level heterogeneity due to foreign atom implantation, requires new investigation and an improved level of understanding which are not presently addressed by the existing by Fowler-Nordheim theory. Thus, there is a crucial need to investigate both the theoretical and experimental interrelations of surface geometry, work function, including field emission parameters, of low energy ion beam irradiated metallic surface for better understanding of the present research results. In the research carried out so far, appropriate ion species of requisite energies and flux (obtained from a microwave plasma based ion source) is utilized to create a variety of atomically heterogeneous systems. Presently, optimization of ion beam fluence to get self organized conical submicron structures and consequently nanostructures on various metallic substrates by low energy (2-2.5 keV) Argon ion beams is carried out. Higher ion beam fluence tends to produce uniformity in nanostructures with well defined hillock like patterns. Surface characterization has been carried out using AFM, SEM, and EDX, providing estimation of their shapes, roughness and the percentage of implanted ions. Current voltage measurement experiment for field emission will be carried out using the modified samples and subsequently the applicability of the Fowler Nordheim equations to describe the results will be investigated. In the future, my goal is to observe these modified surface properties with different type of low energy ion species such as He, Ne, H₂ ion beams. The results of metallic substrate surface modification for different type of ion species with varying fluence along with their field emission experimental results will be presented in the conference. (author)