Negative-ion source applications (invited)

Abstract

In this paper heavy negative-ion sources which we developed and their applications for materials science are reviewed. Heavy negative ions can be effectively produced by the ejection of a sputtered atom through the optimally cesiated surface of target with a low work function. Then, enough continuous negative-ion currents for materials-science applications can be obtained. We developed several kinds of sputter-type heavy negative-ion sources such as neutral- and ionized-alkaline metal bombardment-type heavy negative-ion source and rf-plasma sputter type. In the case where a negative ion is irradiated on a material surface, surface charging seldom takes place because incoming negative charge of the negative ion is well balanced with outgoing negative charge of the released secondary electron. In the negative-ion implantation into an insulator or insulated conductive material, high precision implantation processing with charge-up free properties can be achieved. Negative-ion implantation technique, therefore, can be applied to the following novel material processing systems: the surface modification of micrometer-sized powders, the nanoparticle formation in an insulator for the quantum devices, and the nerve cell growth manipulation by precise control of the biocompatibility of polymer surface. When a negative ion with low kinetic energy approaches the solid surface, the kinetic energy causes the interatomic bonding (kinetic bonding), and formation of a metastable material is promoted. Carbon films with high constituent of sp(3) bonding, therefore, can be formed by carbon negative-ion beam deposition.

Biofunctionalization of silicone rubber with microgroove-patterned surface and carbon-ion implantation to enhance biocompatibility and reduce capsule formation

“…20,21 Tsuji et al 22,23 found that a better adhesion of rat mesenchymal stem cells could be obtained by C-ion implantation at a dose of 3×10 15 ions/cm 2 on the surface of silicone rubber and that when this was done using raster graphics, cell growth could be induced along the direction of the pattern. In this study, we found that dermal fibroblasts grow faster and in a more orderly manner in the case of a silicone rubber surface modified with both microgrooves and C-ion implantation; cell adhesion rate was also increased significantly, and there was an increase in the amount of cell adhesion plaque proteins.…”

Nanocluster Ions and Beam Techniques for Material Modification

“…In addition, an ion is a many-electron particle, which represents the abundant varieties of ion species [10][11][12][13][14][15]. For example, many kinds of ions, as well as several charged states of ions, are available.…”

Chemical Modification of Solid Surfaces at Nano-level by Water Cluster Ion Irradiation

“…It represents several features in material processing, one of which is that it can transfer charge, energy and mass employed for material surface treatment. Another feature is that various kinds of species such as atomic, molecular and cluster ions are available [3,4]. In particular, polyatomic ions such as water and alcohol ions contain several kinds of radicals such as hydroxyl and alkyl radicals, and these radicals have an important role in surface modification and chemical erosion of the surface [5,6].…”