Nobuteru Tsubouchi

Nano-indentation testing for plasma-based ion-implanted surface of plastics

We have developed a technique to modify the surface of plastics to improve the hardness. Carbon ions were implanted with 20 and 10 keV energy into the plastic surface using the conventional ion-implantation and the plasma-based ion-implantation methods. The modified surface was loaded to 1 mN and unloaded using the diamond tip of the nano-indentation equipment. We found that the deformation of the modified surface was elastic deformation. According to the surface Youngs modulus FEM simulation of plastics, surface Youngs modulus was improved from 1.8 to 25 GPa using the plasma-based ion-implantation process.

Simultaneous mass-analyzed positive and negative low-energy ion beam deposition apparatus

Abstract We have developed a new concept low-energy ion beam deposition apparatus. This machine can generate mass-analyzed very low energy ion beams with positive and negative charges at the same time. It is possible to deposit these ions not only simultaneously but also alternatively. The name is Taotron and the nickname is PANDA (Positive And Negative-ions Deposition Apparatus). The aiming specifications of this apparatus are: (1) available positive ions are H, B, C, N, O, Si, Fe, etc. and negative ions are H, B, C, O, Si etc., (2) ion energy range covers 10 eV to 20 keV, (3) typical ion beam current is ≥ 10 μA (for 10 eV oxygen ions with both charges) and the beam size is ≥ 10 mm ⊘, (4) the base pressure of the deposition chamber is in the order of 10 −8 Pa and the pressure during deposition is in the order of 10 −6 Pa.

Carbon nitride thin films formed by low energy ion beam deposition with positive and negative ions

Abstract Carbon nitride became an attractive system for the search of new functional materials since the existence of crystalline carbon nitride was predicted in 1989. Up to now the research in this field is focused mainly on the realization of the hexagonal phase of C3N4, whose properties have been proposed to be of low-compressibility, having a high thermal conductivity, a high optical band gap and insulating character. Ion beam deposition with mass analyzed positive and negative ions is a new technique for depositing thin films under well characterized conditions. With the Positive And Negative ion Deposition Apparatus (PANDA) the simultaneous deposition of low energy carbon and nitrogen ions under ultrahigh vacuum conditions is possible. Depositions were performed on silicon wafers under change of ion species and transport ratios. Rutherford backscattering was used as well as infrared and Raman spectroscopy in order to get compositional and structural information of the deposited thin films. The results are presented together with an overview of carbon nitride solids reported in the literature.

A nitrogen doped low-dislocation density free-standing single crystal diamond plate fabricated by a lift-off process

A nitrogen-doped single crystal diamond plate with a low dislocation density is fabricated by chemical vapor deposition (CVD) from a high pressure high temperature synthetic type IIa seed substrate by ion implantation and lift-off processes. To avoid sub-surface damage, the seed surface was subjected to deep ion beam etching. In addition, we introduced a nitrogen flow during the CVD step to grow low-strain diamond at a relatively high growth rate. This resulted in a plate with low birefringence and a dislocation density as low as 400 cm−2, which is the lowest reported value for a lift-off plate. Reproducing this lift-off process may allow mass-production of single crystal CVD diamond plates with low dislocation density and consistent quality.

Macroparticle-Free Ti–Al Films by Newly Developed Coaxial Vacuum Arc Deposition

Titanium aluminide thin films are deposited on glassy carbon substrates by the coaxial vacuum arc deposition process. A rod-shaped Ti–Al alloy is employed as the evaporation source. In our vacuum arc system, because the spatial position of plasma on the surface of the evaporation source can be controlled by pulsed arc discharge, the thickness of the Ti–Al film can be controlled at nanometer scale. Amorphous stoichiometric Ti–Al films are synthesized from one Ti–Al alloy target at room temperature by changing the number of pulses of the arc discharge. Multilayered Ti and Al films could also be fabricated by changing the target and the number of pulsed arc discharges.

High energy resolution PIXE with high efficiency using the heavy ion microbeam

Abstract An X-ray crystal spectrometer using a position sensitive proportional counter combined with tandem microbeam line at Osaka National Research Institute have been developed. This system realizes high energy resolution PIXE analysis using a heavy ion microbeam (E

Low-resistance p+ layer formation into diamond using heavily B ion implantation

We examine the B dosage dependence of the lattice and electronic structures of a heavily B doped layer formed by multiple-energy B-implantation into diamond (up to 1.7×1017Bcm−2) at an elevated temperature. The resultant highly B doped diamond layer exhibits p-type conduction with very low sheet resistance of 90Ω∕◻ (0.25μm thickness) and low resistivity of 2.3mΩ cm and has temperature-independent transport properties. This suggests that a high-temperature ion implantation technique allows the formation of diamond as a p-type degenerate semiconductor with metallic conduction and provides a useful tool for selective doping required for practical diamond device processing.

Large Single Crystal Diamond Plates Produced by Microwave Plasma CVD

Recent developments in producing large single crystal CVD diamond plates are reviewed. The developments consist of synthesis of large single crystal diamond and production of single crystal diamond plates from the bulk diamond by the lift-off process. Combining these developments, half-inch single crystal CVD diamond plates have been successfully produced.

Optical properties of carbon and carbon nitride films prepared by mass-separated energetic negative carbon and carbon nitrogen ions

Carbon and carbon nitride (CN) films were prepared under ultrahigh vacuum condition by ion beam deposition using isotopically mass-separated, energetic (50–400 eV) negative 12C2− and 12C14N− ions, respectively. The optical properties as well as structures and chemical composition of the films have been characterized and discussed as a function of the kinetic energy of C2− and CN− ions. The structures of carbon and CN films in this study were hydrogen-free amorphous carbon (a-C) like. The N/C composition ratio of the CN films was N/C∼0.4, although the arrival ratio of N/C was N/C=1. The CN film properties depended weakly on kinetic energy of CN− ions, while on a-C films there were kinetic energy dependence of C2− ions of optical constant observed.

Enhanced annealing of damage in ion-implanted 4H-SiC by MeV ion-beam irradiation

The effect of ion-beam annealing for implantation-induced damage in single-crystalline 4H silicon carbide has been studied. Four sets of samples, implanted with two types of ions (C or Si) and two different damage levels (complete or incomplete amorphization), were prepared to investigate the influence of damaging conditions. The damaged samples were irradiated with a 3-MeV Ge ion beam at 600 °C in the range of 1×1015–2×1016cm−2 to induce the ion-beam annealing. Some of the damaged samples were thermally annealed without the Ge irradiation to evaluate pure thermal effects. Rutherford backscattering/channeling for these samples revealed substantial enhancements of damage annealing under the MeV ion-beam irradiation. The enhanced annealing effect was stronger for the incompletely amorphized samples than for the completely amorphized samples. For both cases, the annealing effects almost saturated with increasing ion fluence. The results suggest the competition between the annealing and damaging effects induc...