Endu Sekhar Srinadhu

We report on nano-patterning with multiply charged argon ions that facilitates the self-assembly of epitaxial Cu3Si nanostructures. In particular, we show that the impact sites formed from the dissipation of the incident ion potential energy for Arq+ (q=1,4,8) modulate the growth density and growth rate for silicide nanostructures. The observed nanostructure densities were found to vary as q∼0.9 for strain-driven, shape transition-type growth, and the observed growth rates far exceeded those obtained under thermal conditions. Relating the growth density to an underlying sputter yield for SiO2, we find a dependence on the ion potential energy relatively similar to that observed by others for Iq+ ions incident on a thermally grown oxide.

Polymers are widely used in different types of industries ranging from microelectronics, medical to space applications. However, polymer materials are seldom used in their pristine state and are in need of selective surface treatment to induce a specific response which is a challenging and complex task. Adhesion enhancement of polymers is one of the major requirements that can be achieved with ion beam technology at low cost. Surface enhancement involves keeping the bulk properties of materials unchanged and modifying only the surface properties to achieve optimum results. In this review, we illustrate the use of ion beam technology to modify the surface properties of polymers for potential biomedical and microelectronics applications. This review focuses on effects on the adhesion characteristics for different polymer materials of various optimizable parameters such as type of ion used, ion energy regime (low to medium to high) and the ion fluence range.

Polycarbonate targets were irradiated with multicharged ions of argon and oxygen with kinetic energies between 375 eV and 1 keV. Scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) analysis following the irradiations showed evidence of bond-breaking at the polycarbonate surface. The extent of the ion-induced damage indicates that the ion charge state enhances the damage well beyond that observed for similar, low flux singly charged ions. A qualitative comparison with a simple description of the radius of capture for the initial transfer of electrons between the ion and surface is used to understand the multicharged ion effects.