Kanenaga Fujii

Gold nanoparticles ion implanted in glass with enhanced nonlinear optical properties

Silica glass with dispersed colloid Au particles was synthesized by ion implantation. Colloid Au particles were found to grow through an Ostwald ripening mechanism controlled by diffusion in the silica glass. The third‐order nonlinear optical susceptibility χ(3) of this glass was found to be proportional to the fourth power of the radius of the colloid particles or the fourth power of the absorption coefficient at the peak of a plasmon band when the total volume of the colloid particles was constant. Furthermore, χ(3) of the glass was inversely proportional to the third power of the total volume of colloid particles when the absorption coefficient of the plasmon band was constant.

Controllable laser-induced periodic structures at silicon-dioxide/silicon interface by excimer laser irradiation

Laser‐induced periodical microstructure in a Si substrate covered with a thin layer of silicon dioxide has been studied using KrF excimer laser irradiation for controlling the periodicity. It was found that KrF excimer laser irradiation can produce periodical microstructures in SiO2/Si samples by a single pulse if the laser fluence is large enough when the SiO2 thickness is small. When the SiO2 layer is thick and more than one laser pulse is required, circular patterns can be observed due to the interface defects. The periodicity of the ripple structure linearly depends on the SiO2 thickness. The formation of microstructure does not change the thickness of the SiO2 layer and the crystallinity in the Si substrate. The ripple structure formation in the SiO2/Si structure is related to the thermally generated surface waves. The existence of a SiO2 layer on Si substrate can change the surface tension during the melting of the Si interface and hence control the periodicity of the ripple formation. The lateral p...

High-Dose Implantation of MeV Carbon Ion into Silicon

The formation of SiC in silicon wafer by 1.5 MeV C+ implantation to doses of 1.5×1018 ions/cm2 followed by annealing is demonstrated using infrared absorption spectra and Rutherford backscattering (RBS). From the results of He+ backscattering under the channeling condition, the surface layer of Si is observed to remain crystalline even before annealing.

Titanium Nitride Crystal Growth with Preferred Orientation by Dynamic Mixing Method

Titanium nitride films were produced by dynamic mixing method on four kinds of substrates whose crystal structures differed. By the X-ray diffraction it was observed that the four films had the same preferred orientation. Cross-sectional observation with a transmission electron microscope revealed that an amorphous intermixed layer had formed. The profile of crystal growth on the intermixed layer clearly indicated that the growth started from isotropically oriented small grains and progressed gradually to preferentially oriented columnar grains.

Formation of Au Colloid Particles in Silica Glass by Ion Implantation.

Formation of Au colloid particles and their optical property have been investigated in silica glasses implanted with Au + ions at an acceleration energy of 1.5MeV and fluence levels of 10 16 -10 17 ions/cm 2 . The Au colloid particles are formed in the as-implanted glasses. It is inferred that the average radius of Au colloid particles depends on the fluence level, although the fluence level does not affect the distribution of Au atomic concentration. The heat-treatment little affects the Au atomic distribution. The Au colloid particles grow to 4.3nm in average radius during heat treatment. It is revealed that the large nonlinear optical property of the Au + -ion-implanted silica glass is attributed to the high concentration of the Au colloid particles in the narrow region.

Formation of Crystalline SiC Buried Layer by High-Dose Implantation of MeV Carbon Ions at High Temperature

A buried layer of crystalline SiC in silicon wafer is synthesized by 1.5 MeV C+ implantation at a dose of 1.5×1018 ions/cm2 at a high temperature of 880°C. The infrared absorption spectrum and the X-ray diffraction pattern of this sample show formation of 3C-type SiC crystal. The pole figures of X-ray diffraction show that crystallographic orientation of the SiC buried layer is aligned along the lattice of the Si substrate, that is, topotaxial internal growth of crystalline SiC occurs in a single crystal of Si during the high-temperature ion implantation.

Variation of crystallization with arrival ratio in titanium nitride films formed by dynamic mixing method

Abstract The preferred orientation of titanium nitride films with cubic structure produced at about 400 °C by the dynamic mixing method is studied in the range of the arrival ratio Ti/N from 1.0 to 2.6 and in the case of normal incidence of nitrogen ion beam to the substrate surface. The accelerating voltage of nitrogen ions is 30 kV. The current density of nitrogen ions, in which the numerical ratio of atomic to molecular ions is about unity, is kept at a constant, 0.18 mA/cm2, and the deposition rate of titanium is changed. The composition ratio of titanium to nitrogen in the prepared films are roughly unity, in spite of the large difference of the arrival ratio. The preferred orientation varies from the 〈111〉 axis normal to the surface to the 〈100〉 axis normal as decreasing the arrival ratio, though the film prepared with Ti/N = 1.0 includes a small amount of crystals with the 〈111〉 and 〈110〉 axes as the surface normal and amorphous part. Such a variation of the crystallization is considered to arise by the difference in the energy deposition per a titanium atom.

Formation of CuCl ultrafine particles in silica glass by ion implantation

Abstract Silica glass dispersed with CuCl ultrafine particles is prepared by the implantation of 3 MeV 6 × 10 16 Cl 2+ ions cm −2 and 3 MeV6 × 10 16 Cu 2+ ions cm −2 . It is deduced that the implanted Cu ions form mainly ultrafine Cu metallic particles in the as-implanted silica glass. The ultrafine Cu metallic particles react with Cl atoms to form CuCl ultrafine particles by heating up to 900–1000°C. The number of Cu and Cl ions forming the CuCl ultrafine particles is consistent with the fluence levels of these ions. A large number of CuCl ultrafine particles can be dispersed in silica glass.

Control of preferentially oriented crystal growth of titanium nitride effects of nitrogen adsorption and ion-beam irradiation in dynamic mixing process

Abstract Titanium nitride films which are deposited on a Si wafer by titanium evaporation and simultaneous nitrogen ion-beam irradiation have preferred orientations, which depend on Ti atom/N ion arrival ratio. The effects of nitrogen pressure and ion beam irradiation are discussed to clarify the mechanism of the variation of crystallization. Nitridation with adsorbed nitrogen leads to 〈111〉-oriented TiN crystal growth. Ion bombardment induces 〈100〉-oriented TiN crystal growth. This effect is covered by the nitridation with adsorbed nitrogen, for higher nitrogen pressure case. The difference in the growth rates of 〈111〉-oriented crystals and that of 〈100〉-oriented crystals leads to the variation of prefferred orientations, and so the control of the orientation of crystal growth is available.

Film formation of dititanium nitride by the dynamic mixing method

Abstract Coating film formation of titanium nitride is studied by means of the dynamic mixing method, where the deposition rate of titanium and the current density of nitrogen ions are widely changed and, for the first time, films of the pure Ti 2 N phase are prepared in a narrow range of the ratio of the deposition rate of the titanium and the current density of the nitrogen ions, Ti/N. Under the condition that the ratio Ti/N is larger than for Ti 2 N formation, a film consists of three phases: α-Ti, Ti 2 N and TiN. For lower Ti/N, the prepared films are a mixture of two phases: Ti 2 N and TiN. In the case of a much lower Ti/N only TiN films are prepared.