In recent years, microscale plasmas of mm to μm range have been attracting much attention. Those microplasmas generally operated at high pressure regions, including atmospheric pressure, exhibit characteristics that differ from traditional plasmas at lower pressure regions in their plasma parameters and other parameters originating from their small dimensions. When those characteristics are well combined with the inherent properties of plasmas as reactive, light-emissive and conductive/dielectric media, there appear a variety of potential applications for nano-material syntheses, micromachining tools, microchemical analyses, photonic devices and so on. In this article, the current status and perspective of microplasma research are reviewed from the viewpoints of plasma generation, diagnostics/simulations and new applications, including biomaterial processing.

Plasma spray coating has evolved as a key coating technology for a wide range of industrial engineering such as environmental, energy and biological applications. This is mainly because it enables the deposition of various functional materials and control of the coating interface while maintaining high throughput and ultrafast coating speed characteristics. This technology can still be further developed by introducing novel process principles based on the fundamental understanding of the scientific aspects of this technique. In fact, recently, the controllability in all the aspects involved in the coating process has been improved and new potentials of this processing technique have emerged. As such, the plasma spray technique is anticipated in the near future to evolve into a real next-generation coating technology for new device applications such as large-scale electronics, in which the present technique was formerly not applicable.

Plasma chemical vapor deposition (CVD) and etching using glow discharge are very useful for high technology. However, if all operations must be conducted in a vacuum system, the apparatus and operation costs will be extraor-dinarily high; thus, plasma applications on large materials and gas adsorbed materials such as powder have been impossible in practice. Plasma CVD and surface treatment or cleaning at atmospheric pressure is a promising approach for reducing of costs for mass-production systems. In this paper, we will discuss the basic theory of atmospheric-pressure glow plasma, application studies, and the prospect of plasma systems.

Post scaling technology enabling high-performance in Si-MOSFETs is thoroughly required for next-generation ULSIs. In particular, a technology that induces strain into the channel of a MOSFET is a key to raising mobility. Thin films made from group IV semiconductor materials, such as Ge and Si_1-xGe_x, are available as the suitable stressor for the strained Si channel and now facing the prospect of practical use in MOSFET. On the other hand, the introduction of strain into the device requires a strict control over not only the amount of strain but also its morphology. At the same time, control of dislocations is crucial in terms of their structure, arrangement, and distribution. In this tutorial, we introduce recent developments in strain and dislocation engineering as well as advanced characterization methods for strain-relaxed Si_1-xGe_x layers.

Galactic cosmic rays cause hadronic showers in the terrestrial atmosphere and produce various isotopes. The typical isotope is radiocarbon ¹⁴C. Because the intensity of galactic cosmic rays impinging to the earth depends on the interplanetary magnetic field, which is influenced by solar activity, the production rate of the radiocarbon also reflects the variation of solar activity. In this review, I describe the methods of reconstruction of past solar activity from measurements of radiocarbon and introduce some recent results of the reconstruction.

Original approaches using plasma technology have been performed in order to create carbon-based nanostructures with new properties, as the basis of which various types of unique plasma sources are devised, such as pair-ion plasma, alkali-fullerene plasma, alkali-halogen plasma, microelectrolyte plasma, solution-phase discharge plasma. As a result of the nanoscopic process control of these plasmas, we have succeeded in creating novel nanostructures such as fullerene dimers, purified alkali-metal and atomic-nitrogen encapsulated fullerenes, freestanding individual pristine single-walled carbon nanotubes (SWNTs), ’alkali-metal/fullerene’ junction structure encapsulated SWNTs, and biomolecular-DNA encapsulated SWNTs. Solely C60 and Cs encapsulated SWNTs are found to give rise to p- and n-type semiconducting properties, respectively.

In this paper, we present the production of nanoparticles using reactive plasmas and its application to the deposition of nanocomposite films, as a method of mass producing three-dimensional nanostructures. In this method, nanoparticles several nm in size with a small size dispersion are produced in the gas phase using reactive plasmas, and then the nanoparticles and radicals are codeposited on a substrate. This method realizes a one-step deposition of nanoparticle composite films with a k value of 1.7-3.5 in a controllable way.

Recently, it has been found that femtosecond pulse laser-matter interactions differ in the physics of the ablation mechanism from nanosecond laser ones. As its features, femtosecond laser ablation enables us to realize a periodical nanostructure formation on a solid surface and an ablation rate of angstrom order. Femtosecond laser ablation is useful for surface modification with useful functionality. The femtosecond laser ablation of a carbon nanotube (CNT) cathode is demonstrated. The electron emission from the modified CNT cathode is turned on at an electric field of 1.8V/μm, which is approximately half that for the original CNT cathode. In this article, the results of the modified CNT cathode are presented and future prospects are shown.

Large-area-uniformly plasma under nitrogen atmospheric pressure has been generated using a high-voltage pulse electric field. 　The plasma has been put to practical use effectively applied to the removal of organic contaminants on the surface of a LCD glass substrate and the surface modification of a printed circuit. 　In this study, the mechanism underlying surface cleaning with the atmospheric-pressure nitrogen plasma was considered on the basis of the results of optical emission and X-ray Photoelectron Spectroscopy.

The true mechanism of the onset of crystallization is still unclear. Classical nucleation theory (CNT) assumes the concept of “nucleation” in the 1930s¹. It has thus far been impossible to observe directly nano nucleation due to technical difficulties. Here, we show the direct observation of nano nucleation for the first time by overcoming the above difficulties. The real image of nucleation will enable us to control the ultimate structure and physical properties of materials. We discovered a novel morphology of a “spiral” crystal which is named “spiralite”, in the crystallization of polymers under shear flow. The spiralite rotates, showing high and low growth rates (Vspiral(max) and Vspiral(min)). They are seen along directions perpendicular (Z-axis) and parallel (X-axis) to the flow direction, respectively. It is concluded from a kinetic analysis of accerelation of the growth rate, that Vspiral(max) is an evidence of the formation of the oriented melt on the surface of the spiralite along the Z-axis, due to the significant increase in shear rate γ ⋅ (Z) at the interface.

Facet control during the growth of nitride semiconductors is a promising technique for obtaining a high-quality epitaxial GaN layer with low threading dislocation (TD) density. We have reported that facet-controlled epitaxial lateral overgrowth (FACELO) by metalorganic vapor phase epitaxy (MOVPE) for growth of GaN on a sapphire is a useful technique for reducing TD density and enables us to achieve TD densities on the order of 10⁶ cm^-2. AlGaN with high AlN molar fraction and low dislocation density is necessary for fabricating deep-UV emitters and detectors. A reduction in the TD density of AlGaN over the entire area of a surface was achieved by low-pressure MOVPE using a textured epitaxial AlN substrate. The AlN molar fraction of crack-free AlGaN is 0.51, and the TD density is estimated to be 8.8×10⁷cm^-2 from CL measurement, which is two orders of magnitude lower than that of AlGaN grown on a flat AlN epitaxial layer.