Ion Beam Mixing Technique Research Articles

Transfer-free synthesis of graphene-like atomically thin carbon films on SiC by ion beam mixing technique

Abstract Here we demonstrate the synthesis of graphene directly on SiC substrates at 900 °C using ion beam mixing technique with energetic carbon cluster ions on Ni/SiC structures. The thickness of 7–8 nm Ni films was evaporated on the SiC substrates, followed by C cluster ion bombarding. Carbon cluster ions C4 were bombarded at 16 keV with the dosage of 4 × 1016 atoms/cm2. After thermal annealing process Ni silicides were formed, whereas C atoms either from the decomposition of the SiC substrates or the implanted contributes to the graphene synthesis by segregating and precipitating process. The limited solubility of carbon atoms in silicides, involving SiC, Ni2Si, Ni5Si2, Ni3Si, resulted in diffusion and precipitation of carbon atoms to form graphene on top of Ni and the interface of Ni/SiC. The ion beam mixing technique provides an attractive production method of a transfer-free graphene growth on SiC and be compatible with current device fabrication.

Optical properties of AlGaN nanowires synthesized via ion beam techniques

AlGaN plays a vital role in hetero-structure high electron mobility transistors by employing a two-dimensional electron gas as an electron blocking layer in multi-quantum well light emitting diodes. Nevertheless, the incorporation of Al into GaN for the formation of the AlGaN alloy is limited by the diffusion barrier formed by instant nitridation of Al adatoms by reactive atomic N. The incorporation of Al above the miscibility limit, however, can be achieved by the ion beam technique. The well known ion beam mixing (IBM) technique was carried out with the help of Ar+ irradiation for different fluences. A novel approach was also adopted for the synthesis of AlGaN by the process of post-irradiation diffusion (PID) as a comparative study with the IBM technique. The optical investigations of AlGaN nanowires, synthesized via two different methods of ion beam processing, are reported. The effect of irradiation fluence and post-irradiation annealing temperature on the random alloy formation was studied by the vibrational and photoluminescence (PL) spectroscopic studies. Vibrational studies show one-mode phonon behavior corresponding to the longitudinal optical (LO) mode of A1 symmetry [A1(LO)] for the wurtzite phase of AlGaN nanowires in the random alloy model. A maximum Al atomic percentage of ∼6.3%–6.7% was calculated with the help of band bowing formalism from the Raman spectral analysis for samples synthesized in IBM and PID processes. PL studies show the extent of defects present in these samples.

Effect of heat treatment on surface composition of hydrogen implanted C-SiC coatings

C-SiC coatings were prepared on stainless steel substrate by the middle frequency magnetron sputtering (MFMS) and ion beam mixing technique. After deposition, these samples were implanted by 5 keV hydrogen ion beam at a dose of 1×1018 ion/cm2. Some samples were heat treated at different temperatures from 273 K to 1173 K separately. The surface morphology, surface concentration of the elements of the C-SiC coatings and element iron from substrate as well as their depth profiles were checked with SEM, XPS and SIMS analyses. The results show that the composition of the coatings is changed due to heat treatment at different temperatures. The C-50%SiC coating with an excellent hydrogen resistant property can act as hydrogen barrier at the temperature below 723 K. But the hydrogen resistant property of the coating becomes bad when it is used at the temperature of 1023 K.

Study on synthesis of magnetic nanocomposite (Ni-Teflon) by swift heavy ion beam mixing

The present work envisages synthesis of magnetic nanocomposites by ion beam mixing technique using swift heavy ion irradiation of Ni-Teflon bilayer system and its magnetic characterizations. The nanocomposite is characterized by Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM), scanning probe microscopy (SPM) and superconducting quantum interference device (SQUID) magnetometer. Cross-sectional TEM and magnetic force microscopy (MFM) results confirm the formation of nanocomposite. Magnetic characterizations reveal that nanocomposite exhibits ferromagnetic behavior with an increase in the coercivity, which is attributed to the formation of Ni nanoparticles. The coercivity of the nanocomposite is found to be 112 Oe at room temperature which is two orders of magnitude larger than that of the bulk Ni (0.87 Oe). Copyright © 2011 VBRI press.

Enhanced corrosion resistance of WC-Co with an ion beam mixed silicon carbide coating

Strong adhesion of a silicon carbide (SiC) coating to a WC-Co substrate was achieved through an ion beam mixing technique and the corrosion resistance of the SiC coated WC-Co was investigated by means of a potentiodynamic electrochemical test. In a 1 M NaOH solution, the corrosion current density of SiC-coated WC-Co after heat treatment at 500 °C was about 50 times lower than that for the as-received WC-Co. In addition, the corrosion resistance systematically increases with increasing the SiC coating thickness. On the other hand, for a 0.5 M H 2SO 4 solution, the corrosion current density for SiC-coated WC-Co was about 3 times lower than that for the as-received WC-Co. We discuss the physical reasons for the changes in the corrosion current density with the different electrolytes.

Silicon Nanocluster Prepared Using Ion Beam Mixing Technique

In this work, we present the results of modification of absorption band gap of Silicon nanoclusters (Si-nc) prepared by ion beam mixing on pre-irradiated fused silica. 30 keV Ar+ ions at fluences of 5 x 10(16) to 4 x 10(17) cm(-2) were used to create defects in fused silica glass before introducing Si atoms in the substrate. Si was introduced in the substrates by ion beam mixing using 30 keV Ar+ ions at fluence 1 x 10(17) cm(-2). From UV-Vis absorption spectra, band-gap of Si-nc has been determined for samples prepared at different ion beam-mixing parameters. The absorption edge shifts towards higher energies and size of the silicon nanoclusters decreases with an increase in ion beam fluence used for pre-mixing irradiation.

Formation, Dynamics, and Characterization of Nanostructures by Ion Beam Irradiation

Ion beam irradiation is a potential tool for phase formation and material modification as a non-equilibrium technique. Localized rise in temperature and ultra fast (∼10−12 s) dissipations of impinging energy make it an attractive tool for metastable phase formation. As a matter of fact, a major component of materials science is dominated by ion beam methods, either for synthesis of materials or for its characterization. The synthesis of nanostructures, and their modification by ion beam technique will be discussed in this review article. Formation of nanostructures using ion beam technique will be discussed first. Depending on species (e.g., mass and charge state) and energy range, there are various modes for an energetic ion to dissipate its energy. The role of the electron will also be covered in this article as a basic principle of its interaction with matter, which is same as for an ion. By using a simple reactive ion beam or electron induced deposition, a secondary phase can be nucleated by ion beam mixing techniques, either by using inert gas irradiation or reactive gas implantation on any desired substrate. Nucleation of secondary phase can also be executed by electron irradiation and direct implantation of either negative or positive ions. Post implantation annealing processes are required for the complete growth of clusters formed in most of these ion irradiation techniques. Implantation processes being inherently a non-equilibrium technique, defects always have a role to play in phase formation, amorphization, and beyond (blister formation). When implanted with large energy, even electrons, one of the lightest charged particles, also manifest these properties. Electronic and nuclear energy losses of the impinging charged particle play a crucial role in material modification. Doping a nanocluster, however, is still a controversial topic. Some light will be shed on this topic with a discussion of focused ion beam.

In situ photoelectron spectroscopy study of TiCxNy films synthesized through reactive ion beam mixing

Oxygen-free TiCxNy films have been prepared using the reactive ion beam mixing technique. A 400 Å thick film of Ti was deposited on a float glass substrate and then coated with a 80 Å Carbon layer. These bilayer structures were irradiated by 4 keV nitrogen ions for different nitrogen doses. In situ core level x-ray photoelectron spectroscopy (XPS) measurements were carried out to characterize these films. XPS results revealed that after nitrogen ion bombardment a sufficient amount of nitrogen was introduced in the Ti/C bilayer. On the basis of the binding energy parameters of the Ti 2p, N 1s and C 1s core levels and their shifts from the elemental position, the formation of compound TiCxNy near the surface is confirmed. The XPS result of formation of TiCxNy is supported by x-ray diffraction measurements.

Improvement of Corrosion Resistance and Structural Change in 304 Stainless Steel by means of Ion-Mixing

High-energy ion-beam mixing technique was applied for the surface modification of austenitic stainless steel, followed by electrochemical characterization and microstructural observation. The co-mixing of silicon and chromium resisted the passivation current to 1/1000 relative to the un-modified condition. The corrosion resistance improved remarkably. Microstructural observation revealed that the enhanced diffusion and induced amorphous structure introduced by the co-mixing of silicon and chromium, which played a very important role in the improvement of electrochemical behavior at surface.

The microstructure of transparent and electrically conducting titanium nitride films

The microstructure of electrically conducting and transparent titanium nitride (TiN) films, produced by the dynamic ion beam mixing technique, have been studied. These films consist of small grains of TiN and an amorphous layer. The film is continuous and does not react with the substrate. This paper discusses the morphology and properties of TiN films and their nucleation process.

Recoil implantation of boron into silicon for ultrashallow junction formation: Modeling, fabrication, and characterization

An ion-beam mixing technique is used to fabricate ultrashallow p+/n junctions. In this method, a thin boron layer is first sputter deposited onto the Si wafer surface. Then a 10–40 keV Ge ion beam or −3 kV Ar plasma source ion implantation (PSII) is used to knock the boron atoms into the Si substrate by means of ion-beam mixing. For the thin (0.7 nm) boron layers used in this effort, a selective etch for the removal of boron is unnecessary. Sub-100 nm p+/n junctions have been realized with this method. Numerical simulations, performed to predict the recoiled boron profiles, show good agreement between the simulated and measured data.

イオンビームミキシング法によって作製したＴｉ‐Ｎ系膜の残留応力と諸特性

The residual stress and various characteristics of Ti-N films coated on the surface of SKH51 substrate by ion beam mixing technique were examined. As a result, it was found that the wear characteristic of the films in which Ti2N phase coexisted with TiN phase was better than that of the TiN single phase films, though the dynamic hardness of the former films was lower than that of the latter films. When a small amount of Ti2N phase existed in TiN phase matrix, both the residual stress and the particle size of TiN phase showed a minimum. As to the TiN+Ti2N two phase films coated with the same N/Ti supply ratio, the specific wear rate was decreased when the residual stress of the film was increased.

Titanium nitride for transparent conductors

The transparency of thin films of the electroconductive titanium nitride was demonstrated. Titanium nitride has a high hardness and a high resistance against corrosion, and it is electroconductive. Its color is gold, and it is usually not transparent. Materials can be transparent if they are much thinner than the wavelength of visible light. Formerly, there was no technique available to form such a thin TiN film which is also electroconductive, because very thin TiN crystals grow as small islands. However, by using the dynamic ion beam mixing technique, we succeeded in forming continuous, transparent, and conductive TiN films.

ダイナミックミキシング法による窒化チタン厚膜の形成

ダイナミックミキシング法による窒化チタン厚膜の形成

Development of a crack gauge by using ion beam mixing

The ion beam mixing technique has been applied to develop a crack gauge. This gauge consists of an array of insulator/conductor bands on an insulating substrate which is attached to the test piece. The principle of a gauge is based on the measurement of resistance change brought by cutting of conductive bands due to crack growth in the test piece. An array of insulator/conductor sets was formed by ion bombardment on a thin conductor layer which had been evaporated onto the insulator substrate. For the insulator substrate, SiO 2 was used, and Ru was the conductor. An array pattern was produced with a mask by separating the ion beam. To confirm our idea, a crack gauge of 8×8 mm was fabricated on a compact tension test piece of stainless steel. The spacing of the conductive bands of 0.1 mm width was 0.1 mm. To measure the resistivity, thin multilayers of Si(5 nm)/Ru(50 nm)/Si(30 nm)/SiO 2(300 nm) films were mixed by 300 keV Xe + ions. The resistivity of the mixing region was found to change drastically at the dose of 7 × 10 16 Xe +/cm 2. When the test piece cracked under tension, the gauge measured the crack length with good accuracy.

Charge injection properties of iridium oxide films produced on Ti-6Al-4V alloy substrates by ion beam mixing techniques

The charge injection capabilities of iridium oxide films, as produced on Ti-6Al-4V alloy substrates by ion-beam mixing techniques, were investigated. Iridium oxide is a valence change oxide, and therefore has high values of charge injection density upon voltage cycling in electrolytes. Because of this property, iridium oxide films are useful as working elements in neural prostheses. Iridium films of three thicknesses, produced by sputter deposition followed by ion beam mixing, were tested in cyclic voltammetry out of 1000 cycles or more. Two surface preparations, mechanical polishing and an acid passivation treatment, were also used as controls. Surface analysis was primarily by Rutherford backscattering spectrometry. Both the ion-beam mixing and the acid pretreatment increased the lifetimes of films, in comparison with the mechanically polished standards. Reductions in charge injection capability, when they occurred, were attributed to loss of iridium from the films, and there was a close correlation between the charge injection density and the iridium inventory.

Ion Beam Treatment of Ohmic Contacts to n-TYPE Hg1-xCdxTe

ABSTRACTThe application of ion beam mixing and ion implantation techniques in the formation of ohmic contacts to n-Hg1-xCdxTe (x = 0.6, 0.7) has been investigated. For experiments in ion beam mixing, an indium layer (15nm thick) on Hg1-xCdxTe wasbombarded with 45keV Te+ ions at doses ranging from 1 × 1013 to 1 × 1016 cm2. Minimum values of specific contact resistance, pc, of 4 × 10-4Ωcm-2 were measured for a dose of 1 × 1016 cm-2 after 200°C annealing; pc was independent of dose in this range. Analysis of the interfaces by Auger depth profile and Rutherford backscattering spectrometry has shown that ion beam mixing produced an enhanced indiffusion of indium. In comparison, samples which were ion implanted with In+ at 50keV prior to metalisation showed a reduction in pc which was strongly dependent on dosage.

Amorphous GCr15Ta film formation by dynamic ion beam mixing and the film properties

Ta-rich surface alloys have been prepared directly on GCr15 bearing steel (corresponding to AISI52100 steel) substrates by the dynamic ion beam mixing technique. An amorphous alloy film of a given composition can be formed when the deposition temperature and the atom-ion arrival ratio are controlled appropriately. The microstructure and composition of such films were examined using TEM, EDX and XPS. Corrosion tests in H 2SO 4 and NaCl solutions, as well as friction and wear tests have shown that the amorphous GCr15Ta alloy films formed by this technology have superior chemical and physical properties.

Ion beam induced adhesion in Al/diamond bilayer

Diamond anvil cells are often used to study phase transitions in materials under high pressure. To probe these transitions, electrodes with low resistance and good adhesion properties are desired. Such electrodes were obtained using ion beam mixing techniques. The diamond anvil was first irradiated with a 100 keV Ar + beam with an ion dose of 10 16 ions/cm 2. Resistance measurements of the irradiated area indicated that ion beam damage induced a low-resistance phase of carbon. A thin Al film (≈ 500 Å) was then deposited on the diamond anvil followed by Ar + irradiation. The deposition and irradiation processes were repeated, followed by resistance measurements after each irradiation. The measurements indicate the formation of a low resistance layer ( R ≈ 10gW). A qualitative test of adhesion was performed by scratching the formed layer with the resistance probes. The resistance of the electrode showed an acceptably small increase as a function of scraping. These results can be understood on the basis of recoil mixing in the Al/diamond system.

Adhesion enhancement in Fe-Al2O3 and Cu-Al2O3 metal-ceramic systems induced by ion beam mixing

The ion beam mixing technique is well adapted to treat metal-ceramic interfaces under low temperature and non-equilibrium conditions. Using this technique, we have mixed Cu-Al2O3 and Fe-Al2O1 interfaces in order to improve the adhesion. Cu and Fe metallic layers having thicknesses of less than ~ 100 nm were deposited on optical grade polished surfaces of sapphire substrates. Ion beam mixing experiments were performed at room temperature with xenon, krypton, argon, and neon ions of various energies and fluences ranging from 1015 to 4 x 1016 ions per cm2. A linear increase of adhesion with ion mixing was observed for all the ions and systems studied. A strong dependence of adhesion on the energy transfer, controlled by the nature and energy of the incident ions, was observed, allowing us to optimize the adhesion enhancement in the particular case of the Nebombarded Fe-Al2O3 interface. The microstructural and chemical effects induced at the interface during the ballistic phase of the mixing process responsib...