scholarly journals Experimental Study on the Biological Effect of Cluster Ion Beams in Bacillus subtilis Spores

2019 ◽  
Vol 3 (2) ◽  
pp. 8 ◽  
Author(s):  
Yoshihiro Hase ◽  
Katsuya Satoh ◽  
Atsuya Chiba ◽  
Yoshimi Hirano ◽  
Shigeo Tomita ◽  
...  
Keyword(s):  
Biological Effect ◽  
Biological Effects ◽  
Model Organism ◽  
Lethal Effect ◽  
Molecular Ions ◽  
Ion Beams ◽  
Cluster Ions ◽  
Significant Difference ◽  
Cluster Ion Beams ◽  
Cluster Ion

Cluster ion beams have unique features in energy deposition, but their biological effects are yet to be examined. In this study, we employed bacterial spores as a model organism, established an irradiation method, and examined the lethal effect of 2 MeV C, 4 MeV C2, and 6 MeV C3 ion beams. The lethal effect per particle (per number of molecular ions) was not significantly different between cluster and monomer ion beams. The relative biological effectiveness and inactivation cross section as a function of linear energy transfer (LET) suggested that the single atoms of 2 MeV C deposited enough energy to kill the spores, and, therefore, there was no significant difference between the cluster and monomer ion beams in the cell killing effect under this experimental condition. We also considered the behavior of the atoms of cluster ions in the spores after the dissociation of cluster ions into monomer ions by losing bonding electrons through inelastic collisions with atoms on the surface. To the best of our knowledge, this is the first report to provide a basis for examining the biological effect of cluster ions.

Bombarding Effects of Gas Cluster Ion Beams on Sapphire Surfaces; Characteristics of Modified Layers and their Mechanical and Optical Properties

1995 ◽  
Vol 396 ◽  
Author(s):  
D. Takeuchi ◽  
J. Matsuo ◽  
I. Yamada
Keyword(s):  
Ion Beams ◽  
Solid Surfaces ◽  
Cluster Ions ◽  
Cluster Bombardment ◽  
Damage Layer ◽  
Significant Difference ◽  
Unique Material ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Average Size

AbstractGas cluster ions contain tens, hundreds or even more than thousands of atoms or molecules as ionized particles. It has been shown that the bombarding effects of gas cluster ions on solid surfaces are quite different from those by monomer ions and involve unique material processing characteristics. In order to make clear the bombarding effects, a study of surface modification of sapphire by Ar and CO2 gas cluster ion beams has been performed. Thickness of the damaged layer and surface roughness produced on sapphire depends strongly on cluster ion energy. Damage layer thickness on a sapphire surface bombarded by 150 keV clusters with average size of about 3000 atoms was 40Å. No significant difference was observed in IR transmittance after cluster bombardment. Mechanical properties of sapphire surfaces can be changed by cluster irradiation at a dose of 1011 ions/cm2.

Irradiation Effects of Ar-Cluster Ion Beams on Si Surfaces

1993 ◽  
Vol 316 ◽  
Author(s):  
G. H. Takaoka ◽  
G. Sugahara ◽  
R. E. Hummel ◽  
J. A. Northby ◽  
M. Sosnowski ◽  
...  
Keyword(s):  
Cluster Size ◽  
Ion Beams ◽  
Cluster Ions ◽  
Irradiation Effects ◽  
Damage Layer ◽  
Ion Energies ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
The Mean

ABSTRACTThe effects of energetic Ar cluster ion impacts on Si(111) surfaces have been studied for cluster energies up to l5keV. The mean cluster size was about 1000 atoms, and the smaller sizes could be systematically excluded. Si samples irradiated at different cluster ion energies were analyzed by RBS, ellipsometry, and differential reflectometry. Implantation of Ar in samples irradiated with cluster ions was found by RBS to be detectable, but very small in comparison with samples irradiated with monomer ions of the same energy. The thickness of the damage layer as measured by both ellipsometry and differential reflectometry was also much smaller in the cluster ion irradiated samples.

Surface Planarization with Gas Cluster Ion Beams and Application to Wide-Bandgap Semiconductors

2018 ◽  
Vol 12 (2) ◽  
pp. 170-174 ◽  
Author(s):  
Noriaki Toyoda ◽  
Keyword(s):  
Wide Bandgap ◽  
Ion Beams ◽  
Cluster Ions ◽  
Irradiation Effects ◽  
Atomic Ions ◽  
Smoothing Effects ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Multiple Collisions ◽  
Bandgap Semiconductors

In this study, the fundamental sputtering effects of gas cluster ion beams (GCIBs), especially for surface planarization, are reported. Because gas cluster ions are aggregates of thousands of gas atoms, the collision process for a GCIB, with dense and multiple collisions, differs from that of atomic ions via collision cascading; thus, GCIBs have many unique irradiation effects. Among them, the low-damage and surface smoothing effects are beneficial for the planarization of wide-bandgap semiconductor wafers. The planarization of SiC, diamond, and GaN has been demonstrated using GCIB irradiation.

Secondary Ion Mass Spectrometry with Gas Cluster Ion Beams

2000 ◽  
Vol 647 ◽  
Author(s):  
Noriaki Toyoda ◽  
Jiro Matsuo ◽  
Takaaki Aoki ◽  
Shunichi Chiba ◽  
Isao Yamada ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Ion Beam ◽  
Md Simulations ◽  
Ion Beams ◽  
Cluster Ions ◽  
Ion Mass Spectrometry ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Secondary Ion

AbstractSecondary Ion Mass Spectrometry (SIMS) with Gas Cluster Ion Beams (GCIB) was studied with experiments and molecular dynamics (MD) simulations to achieve a high-resolution depth profiling. For this purpose, it is important to prevent both ion-mixing and the surface roughening due to energetic ions. As the Ar cluster ion beam shows surface smoothing effects and high secondary-ion yield in the low-energy regime, the cluster ion beam would be suitable for the primary ion beam of SIMS. From MD simulations of Ar cluster ion impact on a Si substrate, the ion-mixing is heavier than for Ar monomer ions at the same energy per atom, because the energy density at the impact point by clusters is extremely high. However, the sputtering yields with Ar cluster ions are one or two orders of magnitude higher than that with Ar monomer ions at the same energy per atom. Comparing at the ion energy where the ion-mixing depths are the same by both cluster and monomer ion impacts, cluster ions show almost ten times higher sputtering yield than Ar monomer ions. Preliminary experiment was done with a conventional SIMS detector and a mass resolution of several nm was achieved with Ar cluster ions as a primary ion beam.

Range and Damage Distribution in Cluster Ion Implantation

1996 ◽  
Vol 438 ◽  
Author(s):  
I. Yamada ◽  
J. Matsuo ◽  
E. C. Jones ◽  
D. Takeuchi ◽  
T. Aoki ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Defect Formation ◽  
Incident Beam ◽  
High Energy ◽  
Ion Beams ◽  
Cluster Ions ◽  
Attractive Alternative ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Dopant Redistribution

AbstractCluster ion implantation is an attractive alternative to conventional ion implantation, particularly for shallow junction formation. It is easy to obtain high-current ion beams with low equivalent energy using cluster ion beams. The implanted boron distribution in 5keV B10H14 implanted Si is markedly shallower than that in 5keV BF2 ion implanted Si. The implanted depth is less than 0.04 μm, indicating that cluster ion implantation is capable of forming shallow junctions. The sheet resistance of 3keV B10H14 implanted samples falls below 500 Ω/sq after annealing at 1000°C for 10s. Shallow implantation can be realized by a high energy cluster beam without space-charge problems in the incident beam. Defect formation, resulting from local energy deposition and multiple collisions, is unique for cluster ions. The thickness of the damaged layer formed by cluster ion bombardment increases with the size of the cluster, if implant energy and ion dose remain constant. This is one of the nonlinear “cluster effects,” which may allow some control over the implant damage distributions that accompany implanted ions, and which have been shown to have a great effect on dopant redistribution during annealing

High-speed Processing with Reactive Cluster Ion Beams

2004 ◽  
Vol 843 ◽  
Author(s):  
Toshio Seki ◽  
Jiro Matsuo
Keyword(s):  
High Speed ◽  
Ion Beam ◽  
Beam Current ◽  
Ion Beams ◽  
High Rate ◽  
Cluster Ions ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Sputtering Yield ◽  
Reactive Cluster

ABSTRACTCluster ion beam processes can produce high rate sputtering with low damage in comparison with monomer ion beam processes. Especially, it is expected that extreme high rate sputtering can be obtained using reactive cluster ion beams. Reactive cluster ion beams, such as SF6, CF4, CHF3, and CH2F2, were generated and their cluster size distributions were measured using Time-of-Flight (TOF) method. Si substrates were irradiated with the reactive cluster ions at the acceleration energy of 5–65 keV. Each sputtering yield was increased with acceleration energy and was about 1000 times higher than that of Ar monomer ions. The sputtering yield of SF6 cluster ions was about 4600 atoms/ion at 65 keV. With this beam, 12 inches wafers can be etched 0.5 μm per minute at 1 mA of beam current. The TOF measurement showed that the size of SF6 cluster was about 550 molecules and the number of fluorine atoms in a SF6 cluster was about 3300. If the sputtered product was SiF, the yield has to be less than 3300 atoms/ion. These results indicate that the reactive cluster ions etch targets not only chemically, but also physically. This high-speed processing with reactive cluster ion beam can be applied to fabricate nano-devices.

Sputtering yield measurements with size-selected gas cluster ion beams

2009 ◽  
Vol 1181 ◽  
Author(s):  
Kazuya Ichiki ◽  
Satoshi Ninomiya ◽  
Toshio Seki ◽  
Takaaki Aoki ◽  
Jiro Matsuo
Keyword(s):  
Cluster Size ◽  
Ion Beams ◽  
Cluster Ions ◽  
Energy Conditions ◽  
Si Substrates ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Sputtering Yield ◽  
Sputtering Yields ◽  
Good Agreement

AbstractAr cluster ions in the size range 1000�16000 atoms/cluster were irradiated onto Si substrates at incident energies of 10 and 20 keV and the sputtering yields were measured. Incident cluster ions were size-selected by using the time-of-flight (TOF) method. The sputtering yield was calculated from the sputtered Si volume and irradiation dose. It was found that the sputtering yields decreased with increasing incident cluster size under the same incident energy conditions. The integrated sputtering yields calculated from the sputtering yields measured for each size of Ar cluster ions, as well as the cluster size distributions, were in good agreement with experimental results obtained with nonselected Ar cluster ion beams.

High-speed Processing with Cluster Ion Beams

2003 ◽  
Vol 792 ◽  
Author(s):  
Toshio Seki ◽  
Jiro Matsuo
Keyword(s):  
High Speed ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Ion Beams ◽  
High Rate ◽  
Cluster Ions ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Sputtering Yield ◽  
Reactive Cluster

ABSTRACTCluster ion beam processes can produce high rate sputtering with low damage in comparison with monomer ion beam processes. Especially, it is expected that extreme high rate sputtering can be obtained using reactive cluster ion beams. High current SF6 cluster ion beams were recently obtained with new modifications in the basic cluster ion beam technique. The cluster size distribution was measured with Time-of-Flight (TOF) method and the mean size of cluster was about 500 molecules. Si substrates were irradiated with SF6 cluster ions at the acceleration energy of 5–45 keV. Sputtering yield with SF6 cluster ions was increased with acceleration energy and was about 2300 atoms/ion at 45 keV. The sputtering yield was about 1000 times higher than that of Ar monomer ions and was also higher than that of Ar cluster ions. It was found that reactive sputtering occurred with SF6 cluster ion irradiation. These results indicate that high-speed fabrication can be realized with reactive cluster ion irradiation at high energy.

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