Ion Beam Mixing Effects Research Articles

Ion beam mixing effects in Ag precipitates embedded in MgO crystals

Ion beam mixing effects in Ag precipitates embedded in MgO crystals

Anodic polarization study of the effect of double ion beam mixing on Duralumin corrosion behavior

Protecting films were formed on a Duralumin matrix by using single ion beam mixing (IBM), double IBM and an oxidizing treatment, single anodic polarization and annular polarization curves of all samples were measured in 3% NaCl solution. The pitting resistance of the Cr rich surface alloy produced by double mixing is far better than the protecting films formed by single mixing or by oxidizing treatment. RBS analysis showed that the Cr rich alloy layer formed by double IBM mixed well with the matrix.

Ion beam mixing effects in krypton-irradiated FePd bilayers

We report the results of a study on ion beam mixing effects occurring in 200 keV krypton-irradiated FePd metallic systems. Different techniques were used to characterize the mixed layers: Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy. We observed that the thickness of the mixed region is mainly connected with the thickness of the evaporated palladium layer. After irradiation at the highest dose (2.5 × 10 16 Kr cm −2) different techniques confirm the presence in the mixed layer of the FePd 3 intermetallic phase. The part of the iron film which does not mix with palladium undergoes an α → γ phase transformation.

Effects of ion-beam mixing on the performance and reliability of devices with self-aligned silicide structure

The uniformity of Ti silicide resistance has been greatly improved by using an ion-beam mixing technique. The integrity of both MOS capacitors and p-n junction diodes has been improved. N-channel MOS field-effect transistors fabricated with this technique show better electrical characteristics, less electron trapping in the gate oxide, and better hot-carrier resistance than with devices made without the use of ion-beam mixing. >

Effect of ion beam mixing on the evolution of arsenic from the Au-GaAs system

Effect of ion beam mixing on the evolution of arsenic from the Au-GaAs system

Ion beam mixing effects in Ag precipitates embedded in MgO crystals

MgO single crystals have been implanted at room temperature with 8 × 10 16 Ag cm −2 of 180 keV energy. After 973 K thermal annealing, Ag atoms precipitate in the MgO matrix. The MgOAg samples were then irradiated at 77 K with 800 keV xenon up to 1.7 × 10 16 ions cm −2. The modification of the metallic precipitated phase induced by such ionic bombardment, has been characterized by optical absorption spectroscopy (OAS) and transmission electron microscopy (TEM). The evolution of the optical spectra with xenon bombardment has been interpreted in terms of silver precipitate dispersion induced by ion beam mixing effects. The inhibition of atomic diffusion or radiation induced diffusion, due the low sample temperature during irradiation, increases the efficiency of atomic mixing effects. TEM observations confirm this assumption.

Use of the scratch test to measure changes in adhesion of Cr/Al2O3 due to ion beam mixing

The scratch test is widely used to measure the adhesion of thin films to their substrates. The adhesion improvement with ion beam mixing is difficult to quantify, however, because the mixing process itself introduces changes into the system that affect the measurement of adhesion by the scratch test. This paper described the effect of ion beam mixing on the test parameters and analyzes the results of tests on ion bombarded chromium films on sapphire substrates. The measured force to remove the Cr film increased by more than 1900% due to the ion beam treatment. Changes in the system parameters account for an increase of less than 5%, leading to the conclusion that the ion beam treatment caused a major increase in the bond strength.

Combined Effect of Ion Implantation and Ion Beam Mixing on Metal Surface

ABSTRACTThe article is an account of the development of a new technique to improve the surface properties of materials by ion beam bombardment combined effect of ion implantation and ion beam mixing.Ti+ ion beam has been used to mix the surface of Cr-deposited on to Fe or to implant Ti+ into the surface of Fe. By comparing the electrochemical properties, it has been shown that the corrosion resistance of Cr-deposited Fe surface mixed with Ti + ion beam is much better than that of Ti+ ion implanted Fe surface, the critical current density Ic and minimum anodic passive current density Im are decreased by one order of magnitude in deacrated 1M CH3 -COONa-CH3 COOH solution (pH 7.3, 25°C). AES and SIMS observation show Nhat the gombined effect of implantation and mixing has been really achieved.

イオンビームミキシングにおける粒成長機構 Ａｌ‐Ｍｎ系を中心に

The kinetics and grain growth mechanism in ion beam mixing have been investigated for the AI-Mn system. First, we determined the temperature dependence of mixing rate using Rutherford backscattering and then the phases formed by ion beam mixing were characterized by x-ray and electron diffraction analyses. The present experiments demonstrate that the residual diffusive motion is the decisive factor for direct formation of the various phases of intermetallic AI-Mn alloys. The residual diffusivity depends strongly on the mixing temperature and its relaxation time ranges from 10-12 up to l0-6 sec or longer. Finally, a model describing the ion beam mixing effect is proposed.

Effects of ion-beam mixing on the epitaxial growth of MoSi2 on (111)Si

Both plan-view and cross-sectional transmission electron microscopy as well as sheet resistance measurement have been applied to study the effects of As+ ion-beam mixing on the epitaxial growth of MoSi2 on (111)Si. Significant improvement in the epitaxial growth of MoSi2 on (111)Si and lower electrical resistivity of the MoSi2 overlayer were found as a result of ion-beam mixing. Island formation was almost completely alleviated in samples implanted under suitable conditions and subsequently annealed up to 1100 °C. The dispersion of impurities near the Mo/Si interface and/or the generation of defects as a result of the ion-beam mixing are thought to be particularly beneficial to the growth of MoSi2 epitaxy on silicon. The ineffectiveness of the ion-beam mixing for the improvement of the silicon surface coverage in some instances is attributed to the more pronounced accumulation of As atoms at the MoSi2/Si interface to increase the interface energy so that island formation becomes energetically more favorable.

Ion beam mixing effects in the Ar +-irradiated Fe/SiO 2 system

Ion beam mixing effects at the metal/insulator interface have been studied by irradiating at room temperature the Fe film/SiO 2 substrate system with 100 keV Ar ions in the fluence range 3 × 10 15 – 1.3 × 10 17 ions/cm 2. The aim of the work was to quantify the ion induced mixing of Fe atoms and clarify the mechanisms involved in the atomic transport processes. SEM analyses of the irradiated surfaces reveal ion beam induced surface morphological modifications as hole formation in the Fe film and Fe island growth. Computer controlled image analyses allowed us to evaluate the Fe coverage at any irradiation fluence, φ , and to introduce a fluence dependent “coverage” factor ƒ(φ) in calculations. The amount of mixed Fe atoms, Q m, has been measured by 1.8 MeV He + Rutherford backscattering, after a chemical etching procedure to remove the unmixed Fe film. The mixing process is well described by the relation Q = Aφ + B√ φ, indicating that both collisional and diffusive mechanisms are effective. The relative influence of these two main mechanisms has been evaluated by determining the coefficients A and B, taking into account the morphological effects expressed by the “coverage” factor ƒ(φ).

The effect of ion beam mixing on MoSi 2 formation

Thin Mo films on Si were mixed by As * ion bombardment at room temperature. This results in an amorphous intermixed layer of varying composition and, at greater depth, in the amorphization of silicon. The formation of MoSi 2 from these implanted structures by thermal reaction has been studied by glancing angle Rutherford backscattering and in situ annealing. These experiments show that ion beam mixing of the interface disperses the interfacial oxide, which is present between Mo and Si and initially a homogeneous reaction occurs. However, when the amorphized silicon has regrown epitaxially, the reaction becomes inhomogeneous or even stops. The dispersed oxygen is apparently snowploughed in front of the interface of amorphous and crystalline silicon leading to a restoration of the oxide barrier.

The Effect of Formation Conditions on the Structural and Electrical Properties of Ultrathin Cobalt Silicide Films

ABSTRACTWe have studied the dependence of the structural and electrical properties of ultrathin cobalt silicide films on the annealing temperature and deposited Co thickness.We recently reported that coherent, electrically continuous films of CoSi2 could be grown on Si(111) with thicknesses as small as 1 nm.1 The thinnest of these films had a high density of pinholes which covered about 20% of the area of the substrate. The resistivity of the films increased dramatically with decreasing thickness in a manner which was qualitatively consistent with quantum size effects. In order to investigate the dependence of both the pinhole density and the resistivity of ultrathin CoSi2 films on Si(111), we have deposited different thicknesses of Co onto near room temperature (<100°C) Si(111) substrates and have annealed the samples at different temperatures in order to study the effect of silicide formation conditions on the structural and electrical properties of the resulting films.Co layers were deposited onto Si(111) wafers in a molecular beam epitaxy apparatus as described previously.1 In our earlier work, CoSi2 was formed by heating the sample to ∼600°C for a few seconds after Co deposition. Because higher temperature anneals are known to lead to pinhole formation in thicker films,2 annealing temperatures in the present experiments were constrained to be 600° or less. The reaction time was on the order of 5 minutes. The layers were examined using plan-view transmission electron microscopy (TEM) in order to avoid beam heating and ion beam mixing effects which might cause artefacts in cross-section TEM observation.The results of our experiments are summarized in Figure 1. The figure indicates the silicide phases found in a film as a function of deposited Co thickness and annealing temperature. The numbers in each square correspond to the residual resistivity, ρo, measured for each film. Perhaps the most striking finding of this study is the abrupt change in the structure of the films between 0.7 and 1.4 nm of deposited Co. For all temperatures investigated (including near room temperature), films formed by depositing less than 1 nm of Co form CoSi2 immediately upon deposition. (For films approaching this thickness, there is also a small amount of Co2Si which persists at all temperatures

Effect of ion beam mixing on wear and friction of Fe-Ti multilayered structure on AISI 304 stainless steel

Dry sliding properties of ion beam mixed multilayered Fe-Ti structures deposited on AISI 304 stainless steel were studied over the composition range 0–100% Ti using samples with a linearly varying composition of constituents. Our measurements revealed that a ductile surface was formed with good sliding properties over the wide composition range by ion beam mixing of deposited layers. These beneficial effects were not obtained on as-deposited samples or by ion bombardment of either a substrate or pure iron layer deposited on a substrate. Thus, it is concluded that both the ion beam processing and composition as well as the resulting microstructure are essential for improved tribology.

Sliding life enhancement of a WS2 sputtered film by ion beam mixing

The ion beam mixing effect on the tribological properties of the WS2 sputtered film is investigated. The film morphology and crystal structure related to the tribological properties are also examined. It is determined that a film so prepared has both lower friction and longer sliding life than an as-sputtered WS2 film. Scanning electron micrograph and reflection high-energy electron diffraction examinations suggest that the ion beam mixing effect can be attributed to crystalline precipitate formation resulting from recrystallization caused by the implantation.

Ion beam mixing effects on the high temperature oxidation resistance of iron and nickel

Iron or nickel substrates were coated with thin films of tin (or boron) and bombarded with 100 keV Xe + ions (or N + ions). Surface modifications were studied using scanning electron microscopy, X-ray diffractometry and Auger electron spectroscopy. The high temperature oxidation of the specimens was studied by two series of experiments. Mass gain data and the observed resulting oxide morphology and composition indicated that the treated surfaces inhibit oxidation in air. Oxidation of other samples in the pre-chamber of the spectrometer and Auger analysis of these samples confirmed the improved oxidation resistance.

Status of conversion electron mössbauer spectroscopy in ion implantation studies

In this paper, some new developments in conversion electron Mössbauer spectroscopy (CEMS) and its recent applications in the study of ion-implanted materials are presented. On-beam CEMS measurements are now possible at temperatures from 4 to 1200 K in ultrahigh vacuum. The range of applications of the 57Fe resonance is rapidly expanding and experiments with 119Sn, 151Eu and 197Au have recently been initiated. A brief survey of current research subjects is presented; this includes local packing and charge transfer effects in iron-implanted alloys, formation of multiple charge states and annealing effects in inorganic insulators, light ion implantation effects in steels, ion beam mixing effects and applications in materials studies for thermonuclear fusion.

Ion beam mixing of FeTi multilayers

Iron and titanium multilayers for which the total thickness was in the range 70–150 nm and the average composition was Fe-50at.% Ti have been ion beam mixed at room temperature with 500 keV Xe + ions. The samples were characterized before and after ion beam mixing with doses from 1×10 15 to 3×10 16 Xe + ions cm −2 by three complementary techniques: Rutherford backscattering spectroscopy of 2 MeV α particles, conversion electron Mössbauer spectroscopy and transmission electron microscopy. A dose of at least 1×10 16 Xe + ions cm −2 is necessary for a significant ion beam mixing effect to be observed and for a dose up to 3×10 16 Xe + ions cm −2 the formation of the compound FeTi occurs. This compound is observed in the form of microcrystallites in spite of the presence of a large amount of impurities such as carbon and oxygen which are known to be easy glass formers.

Phase Transformations In Nickel-Aluminum Alloys During Ion Beam Mixing

ABSTRACTThe effect of ion beam mixing of nickel-aluminum alloys with 500 keV krypton ions has been investigated over a range of temperature, composition, ion dose, and post-irradiation thermal treatments. Samples were formed by aternate evaporation of layers of aluminum and nickel. A portion of these samples was subsequently annealed to form intermetallic compunds. Irradiations were performed at both room temperature and 80 K using the 2 MV ion accelerator at Argonne National Laboratory. Phase transformations were observed during both in situ irradiations in the High Voltage Electron Microscope(HVEM) at Argonne and also in subsequent analysis of an array of irradiated samples. Electron diffraction indicates the presence of metastable crystalline structures not present in the conventional nickel-aluminum phase diagram. Transformations occur at doses as low as 5×1014 cm−2 and continue to develop as the irradiation progresses up to 2×l016 cm−2. Layer mixing is followed through Rutherford Backscattering analysis. Samples are also checked with x-rays and Electron Energy Loss Spectroscopy (EELS). A thermodynamic argument is presented to explain the phase transformations in terms of movements on a free energy diagram. This analysis explains the interesting paradox concerning the radiation hardness of the NiAl[l] phase and the amorphous structure of mixed Ni-50% Al layers[2].

Formation of GaAs Ohmic Contacts by Using Ion Beam Mixing

ABSTRACTIon beam mixing effects on metals and highly doped semiconductors on GaAs for formation of ohmic contacts have been studied. In this study, we have principally selected Pt as metal and Ge as semiconductors electrodes for GaAs. In Pt/GaAs system, we observed alloying phenomena induced by Si+, Ar+, Ge+ ion mixing effects. The amount of GaAs reacted with Pt was found to be proportional to the mass of the incident ions for constant dose. Concernig with the formation of ohmic contacts, only in the case of Si implantation through Pt films, the conversion from Schottky- to ohmic-contact was observed due to ion beam mixing effects. In Ge/GaAs system, we observad the solid state epitaxy for implanted Ge layer by the first annealing at 450°C in the two step annealing, but no activation of the implanted species. For activating implanted species, the second annealing at 800°C was effective. Concerning with the formation of ohmic contacts, we observed that the ohmic I-V characteristics for Ge/GaAs system could be obtainable when the following conditions were satisfied at the same time: 1) high dose implantation of As+ into Ge layer, 2) low dose implantation of Si into Ge/GaAs boundary and 3) relatively short period annealing in the second annealing step. From such study, it is concluded that ion beam mixing in conjunction with rapid annealing would be most promising for forming stable and reproducible ohmic contacts.