Laboratories

National Institute for Materials Science (NIMS), Quantum Beam Center Ion Beam Group
Heavy Ion Laboratory

Type of organization

Contact address

member of laboratory

Research field

Research theme

Purpose and background of research

Heavy ion laboratory in Nanofunction Group aims at achievement of extreme fields interactive with materials, detection/evaluation of quantum interactions between materials and the extreme fields, and development of material functions originated in nano-scale structures. The material function inherent in nano-scale structures is called Nanofunction. The extreme fields we deal with are ions, photons, neutral atoms and ultra-high vacuum. The nanofunctions we aim at are photonics, spintronics due to nanoparticles, nanocoating, nanotransport and nanomechatronics.

Methodology and originality

Heavy Ion Laboratory aims at attaining Extreme Particle Fields strongly interactive with materials and at applying them for materials processings. By in-situ measurements of the highly non-equilibrium processes, the interaction mechanisms including radiation damage are revealed and the understandings are utilized to develop novel functions of materials. This laboratory has established techniques of heavy-ion fields of MeV-mA, which had not been attained before, and also a hybridization technique of high-power photon fields. To focus on the dynamical processes, unique in-situ devices are integrated into the EPF-accelerator system. The Extreme Particle Fields, which have both extreme and non-equilibrium natures, have characteristic features of different freedoms, that is, a mass flow (ions) and pure electronic excitation (photons), and are promising to develop new tools for materials science. As a specific application of high-flux heavy ions, which are comparable with atomic density of gaseous film-growth techniques, we apply the EPF to control spatial structures of metal-nonmetal material systems. Particularly, metal nanocrystals have attracted our attention as promising candidate materials for nonlinear optical properties, such as optical switching, oscillation etc. In our laboratory, we develop nanofabrication technology and novel material functions due to quantum size effects and/or atomic scale structures, on the basis of understandings of fundamental mechanisms of non-equilibrium processes, such as beam-solid interactions, metal atom-point defect interactions and phase transformation, by evaluating atomic structures, time-resolved optical properties and nonlinear susceptibilities.

Major insturments

Result and impact

Heavy Ion Laboratory has succeeded in fabricating a 2D structure of metal nanospheres in a self-organizing manner, with their unique technique of high-current negative ion implantation. The self-assembly under high-energy ion implantation is the first discovery in the ion implantation fields. The nonlinear optical property and the ultrafast response of picoseconds have been achieved for the spatially controlled structures. Metal nanoparticles embedded in transparent insulators are one of the most promising candidates for nonlinear optical elements which are a key of ultrafast telecommunication in the future IT society. Since the optical properties are determined by nanoparticle morphology, such as particle size, number density and spatial distribution, the morphology control of nanoparticles is one the most important engineering issues. Particularly for optical integrated circuits, one of the most important and fundamental structures is a 2D structure or a shallow assembly of nanoparticles. Up to now, various methods, from ceramics-industrial ones to state-o-the art methods, have been applied to fabricate nanoparticles in the insulators. Among those fabrication methods, the ion implantation technique has been regarded as a superb method to provide spatial controllability and as the most promising candidate for industrial applications. However, if one uses common positive ions for the implantation, the insulating surface inevitably builds up surface charges and the Coulomb repulsion impedes precise implantation or even stops the implantation in itself, particularly for ion implantation at low/medium energies (1- several 10's keV). Accordingly, 2D fabrication of nanoparticles by ion implantation had been difficult.