Vapor Vacuum Arc Ion Source Research Articles

Rhenium ion beam for implantation into semiconductors

At the ion source test bench in Institute for Theoretical and Experimental Physics the program of ion source development for semiconductor industry is in progress. In framework of the program the Metal Vapor Vacuum Arc ion source for germanium and rhenium ion beam generation was developed and investigated. It was shown that at special conditions of ion beam implantation it is possible to fabricate not only homogenous layers of rhenium silicides solid solutions but also clusters of this compound with properties of quantum dots. At the present moment the compound is very interesting for semiconductor industry, especially for nanoelectronics and nanophotonics, but there is no very developed technology for production of nanostructures (for example quantum sized structures) with required parameters. The results of materials synthesis and exploration are presented.

Al Ion Implantation of SiC Coated Carbon Fiber-Reinforced SiC Matrix Composites by Metal Vapor Vacuum Arc Ion Source

SiC coated carbon fiber-reinforced SiC matrix (C/SiC) composites were implanted with aluminum ions by metal vapor vacuum arc ion source to improve their oxidation resistance. Depth profile of the aluminum ions in the SiC coated C/SiC composites was checked by Auger electronic energy spectrum. Oxidation tests were performed in flowing dry air at 1300°C on the SiC coated C/SiC composites. The samples with ion implantation exhibited lower weight loss than those without aluminum ion implantation. The surface morphologies of the samples were obtained by scanning electronic microscope. As compared with the mechanical properties of the samples without ion implantation, those of ion-implanted samples changed little.

Optical Limiting Properties of Ag-Cu Metal Alloy Nanoparticles Analysis by using MATLAB

Ag-Cu alloy nanoparticles were formed by sequential ion implantation (Ag and Cu) in silica using a metal vapor vacuum arc (MEVVA) ion source. Third-order nonlinear optical properties of the nanoparticles were measured at 1064 nm excitations using the Z-scan technique. Curve fitting analysis, based on the MATLAB features for Ag-Cu alloy nanoparticle optical limiting experiments, is used. The results show that Ag-Cu alloy nanoparticles display a refractive optical limiting effect at 1064nm.

Nonlinear optical response of silica doped with copper nanoclusters under 1064 nm laser excitation

Metal nanocluster composite glass was formed by Cu ion implantation into silica using metal vapor vacuum arc (MEVVA) ion source. The microstructural properties of the nanoclusters were analyzed by optical absorption spectra and transmission electron microscopy (TEM). Third-order nonlinear optical properties of the nanoclusters were measured at 1064 nm excitations using Z-scan technique. The nonlinear refraction index, nonlinear absorption coefficient, and the real and imaginary parts of the third-order nonlinear susceptibility were deduced. The mechanisms responsible for the nonlinear response were discussed. Third-order nonlinear susceptibility χ (3) of this kind of sample was determined to be (4.2 ± 1.0) × 10 − 8 esu.

Si Ion Implantation-Induced Defect Photoluminescence in Silica Films

Dry and wet oxidation silica films doped with silicon ions were prepared using metal vapor vacuum arc (MEVVA) ion source implanter. The does of Si ion beams were kept constant at 3×1016 /cm2 and the energy varied from 42KeV to 70KeV. Five photoluminescence (PL) bands at the wavelength of 560nm, 580nm, 620nm, 650nm and 730nm have been observed at room temperature in all samples. The results of XRD showed none of Si nanocrystals were formed in the as-implanted silica films and originations of the PL bands were defects introduced by implantation. The 560nm PL band originated from oxygen surplus defect small peroxy radical (SPR), whereas the PL bands which ranges from the wavelength of 620nm to 730nm were attributed to non bridge oxygen hole center (NBOHC). Elevating implantation energy resulted in intensity increasing of 560nm PL band of dry oxidation samples but had inverse effects on wet oxidation samples. Influence mechanism of implantation energy on the defect photoluminescence was discussed in this article.

Effect of high-energy carbon ion implantation on Ti–Al–Si–N coatings by metal vapour vacuum arc

Due to the combination of high hardness, good thermal stability and oxidation resistance, Ti–Al–Si–N coatings have become an excellent candidate for use as high speed machining coatings. Nowadays ion implantation has been employed to alter the near-surface structure and properties of semiconductors, metals and metal alloys without the loss of bulk properties. The present research investigated the effect of carbon ion implantation on the structural, mechanical and tribological properties of the Ti–Al–Si–N coatings prepared by reactive unbalanced magnetron sputtering. Carbon implantation was carried out by metal vapour vacuum arc ion source (MEVVA) with different carbon ion doses. After implantation, the samples were investigated systematically by means of the Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), cross-sectional transmission electron microscopy (TEM), X-ray photo-electron spectroscopy (XPS), surface profilometry (PGI), nano-indentation measurement and ball-on-disk test etc. The results showed that the implantation depth, chemical composition, microstructure and nanohardness depended strongly on the implanted carbon doses. In addition, a great improvement on the tribological performance was observed with the post-treatment process of carbon ion implantation.

A Study of the Structural, Mechanical and Tribological Properties of Ti-Al-N Coatings Post-Treated by Carbon Implantation

Carbon ion implantation has often been considered as an additional method to further improve the wear, corrosion and oxidation resistance of hard coatings on tools or machine parts. The present research investigates the effect of carbon implantation on the structural and mechanical properties of the sputter-deposited solid solution Ti-Al-N coatings. The carbon implantation was carried out by using metal vapour vacuum arc ion source (MEVVA) with solid cathode at energies of 5 and 50 keV, and a dose of 6×1017 atoms cm-2. The mechanical and the microstructure properties of the implanted layer were identified by a variety of analytic techniques, such as nano-indentation, x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) etc. Additionally, the wear performance of the samples was evaluated by a typical ball-on-disk tribometer in dry conditions. The results showed that the coatings with high energy carbon implantation exhibited an enhanced hardness. The improved hardness could be attributed to the formation of TiC phase, as indicated in XPS. In the sliding tests, the coatings with the post-treatment of carbon implantation showed an improved tribological property in terms of friction coefficient and wear rate. The friction coefficient could be reduced from 0.6 to 0.1. The coatings had ten-fold better wear resistance than the coating without ion implantation.

A micro X-ray fluorescence analysis method using polycapillary X-ray optics and grazing exit geometry

Grazing exit X-ray fluorescence (GE-XRF), which has unique advantages in surface and film analysis, is a development of XRF related to total reflection XRF. The combination of polycapillary X-ray optics with total reflection geometry in the detection path allows micro analysis in thin layer characterization. This technique was applied to analyze a series of titanium and iron layers which were deposited on GaAs single crystal by metal vapor vacuum arc ion sources. Thickness and density of the layers result from fitting the experimental data to model calculations, and the information of layer uniformity can be acquired by two-dimensional scan analysis. The GE-XRF method has application for complete layer characterization and process control during the layer deposition.

CHARACTERIZATION OF SURFACE COMPOSITION AND MICROSTRUCTURE OF H13 STEEL IMPLANTED BY Ti IONS USING MASKING IMPLANTATION PROCEDURE

Ti and C ions extracted from a metal vapor vacuum arc ion source (MEVVA) were implanted into H13 steel using a masking procedure to ensure reproducible conditions for testing and subsequent analysis. An optical interference microscope and pin-on-disc apparatus investigated the wear and friction characteristics of the steel. The Ti concentration depth profile from Rutherford backscattering spectroscopy was compared with that calculated by a TRIDYN code. It was observed by grazing-angle X-ray diffraction and transmission electron microscopy that carbide of Ti appeared in the doped region. The concentration depth profile and microstructure analysis can serve to illuminate the wear resistance improvement mechanisms of the Ti -implanted steel.

Correlation between impurities in Fe–Si amorphous layers synthesized by Fe implantation and photoluminescence property of β-FeSi 2 precipitates in Si

Completely amorphous Fe–Si layers are formed by Fe implantation into Si substrate at a dosage of 5×10 15 cm −2 using a metal vapor vacuum arc (MEVVA) ion source under 80 kV extraction voltage and cryogenic temperature. After thermal annealing, β-FeSi 2 precipitates are formed in Si matrix. The influence of impurities in these amorphous Fe–Si layers on the photoluminescence (PL) from β-FeSi 2 precipitates is investigated. PL is found to be significantly enhanced by optimizing the impurity concentration and annealing scheme. After 60 s of rapid thermal annealing (RTA) at 900 °C, β-FeSi 2 precipitates in medium boron-doped Si substrate give the strongest PL intensity without boron out-diffusion from them.

Fabrication of silicon carbide nanowires/carbon nanotubes heterojunction arrays byhigh-flux Si ion implantation

An array of silicon carbide nanowire (SiCNW)–carbon nanotube (CNT) heterojunctionswas fabricated by high-flux Si ion implantation into a multi-walled carbon nanotube(MWCNT) array with a metal vapor vacuum arc (MEVVA) ion source. Under Siirradiation, the top part of a CNT array was gradually transformed into an amorphousnanowire array with increasing Si dose while the bottom part still remained aCNT structure. X-ray photoelectron spectroscopy (XPS) analysis shows that theSiC compound was produced in the nanowire part even at the lower Si dose of5 × 1016 ions cm−2, and the SiC amount increased with increasing the Si dose. Therefore, the fabrication of aSiCNW–CNT heterojunction array with the MEVVA technique has been successfullydemonstrated. The corresponding formation mechanism of SiCNWs was proposed.

Surface morphology evolution of amorphous Fe–Si layers upon thermal annealing

Changes in the surface morphology of ion-beam-synthesized amorphous Fe–Si layers after rapid thermal annealing (RTA) and furnace annealing (FA) were investigated using atomic force microscopy and transmission electron microscopy. Completely amorphous Fe–Si layers were formed by Fe implantation at a dosage of 5 × 1015 cm−2 using a metal vapour vacuum arc ion source under 80 kV extraction voltage and cryogenic temperature. After RTA at 850 °C, β-FeSi2 precipitates in Si are completely aggregated from this amorphous Fe–Si layer and the surface of the implanted layer remains flat. To date, no obvious photoluminescence (PL) spectrum has been reported from RTA treated β-FeSi2 precipitates. However, after annealing at 850 °C for 40 s, high-quality β-FeSi2 precipitates in Si are obtained which clearly show 1.5 µm PL at 80 K for the first time. Even though additional long-term FA at 850 °C can enhance PL intensity to a limited extent, the longer thermal treatment induces the outdiffusion of β-FeSi2 precipitates and degrades the surface flatness.

Origin of Ferromagnetism in Co-Ion-Implanted Anatase TiO2 Thin Films

Ferromagnetic Co-doped anatase TiO2 films were prepared by implantation of Co ions into TiO2 thin films using a metal vapor vacuum arc ion source at various beam currents. The saturation magnetization (Ms) of these films increased with annealing temperature. The maximum Ms observed was about 2.3 µB/Co. High-resolution transmission electron microscopy and X-ray photoelectron spectrometry were performed to study the possible origin of the ferromagnetism. It is believed that the high magnetic moment values observed are associated with Co atoms doped to the Ti2+ sites and the intermediate spin state.

COMPARISON OF WEAR RESISTANCE MECHANISMS OF DIE STEEL IMPLANTED WITHCANDMoIONS

Mo and C ions extracted from a metal vapor vacuum arc ion source were implanted into the surface of die steel (H13) to compare the wear resistance mechanisms of the implanted samples, respectively. The concentration depth profiles of implanted ions were measured using Rutherford backscattering spectroscopy and calculated by a code called TRIDYN. The structures of the implanted steel were observed by X-ray photoelectron spectroscopy and grazing-angle X-ray diffraction, respectively. It was found that the conventional heat-treated H13 steel could not be further hardened by the subsequent implanted C ions, and the thickness of the implanted layer was not an important factor for the Mo and C ion implantation to improve the wear resistance of the H13 steel. Mo ion implantation could obviously improve the wear resistance of the steel at an extraction voltage of 48 kV and a dose of 5 × 1017cm-2due to formation of a modification layer of little oxidation with Mo2C in the implanted surface.

Field emission from gadolinium silicide prepared by ion implantation with electron beam annealing

A silicon-based field emission cathode, the rare earth silicide GdSi2 was prepared by implanting Gd ions into silicon using a metal vapor vacuum arc ion source and subsequently annealed by electron beam. For as-implanted samples, turn-on field was about 21V∕μm at a current density of 1μA∕cm2 and a field emission current density of 1mA∕cm2 was reached at an applied field of 34V∕μm. After annealing, the turn-on field could be as low as 9V∕μm and the current density of 1mA∕cm2 can be reached at an applied field of 14V∕μm. X-ray diffraction with x-ray photoelectron spectroscopy analyses and atomic force microscopy were used to characterize microstructure changes of the samples. The results showed that these excellent field emission characteristics were attributed to the GdSi2 compounds formed in the samples. The field emission mechanism was discussed in terms of Fowler-Nordheim (FN) theory. It was found that FN plots could be divided into two segments obviously, and this was perhaps because of the thermal effect in the process of field emission.

Post-annealing effect on the microstructure and photoluminescence properties of the ion beam synthesized FeSi2 precipitates in Si

FeSi2 precipitates with various structural properties embedded within silicon matrix were formed by iron ion implantation using a metal vapor vacuum arc ion source followed by thermal annealing at various conditions. The microstructure and phase properties of the implanted samples were studied by transmission electron microscopy. The orientation relationships and thus the interfacial coherence between the FeSi2 precipitates and the Si matrix were observed to change with the annealing conditions. A good correlation is identified in-between the structural properties and the photoluminescence properties of these samples.

Structures and light emission properties of nanocrystalline FeSi 2/Si formed by ion beam synthesis with a metal vapor vacuum arc ion source

Thin layers of nanocrystalline FeSi 2 embedded in Si structures have been formed by Fe implantation using a metal vapor vacuum arc (MEVVA) ion source under various implantation and thermal annealing conditions. The microstructures were studied in details and correlated with the photoluminescence (PL) properties. It is found that higher lattice coherence between the FeSi 2 nanocrystals and the Si matrix is associated with better light emission efficiency. Multiple-cycle implantation schemes were introduced and it is shown that with appropriate process design the dose quenching effect can be suppressed to achieve light emission enhancement in higher dose samples. De-convolution of the PL spectra into two or three peaks was performed and their temperature and excitation power dependence were analyzed. The analysis results indicate that the 1.55-μm emission really originated from FeSi 2 and that the emission peaks are likely donor- or accepted-level-related. MOS structures with the incorporation of implanted nanocrystalline FeSi 2 were fabricated. Electroluminescence (EL) spectra from these devices showed two peak features of which one peak corresponds to FeSi 2 emission and the other corresponds to enhanced Si band-edge emission. Clear room-temperature EL signals from these device structures were observed. A model is proposed to qualitatively understand the temperature dependence of the EL spectra.

Effects of Annealing on Structural and Magnetic Properties of Cobalt Implanted TiO2 Thin Films

AbstractSince the observation of room-temperature ferromagnetism (RTFM) in Co-doped anatase TiO2 [1], there have been many reports on the study of the magnetic properties of Co-doped TiO2 prepared by various methods with diversified results. The origin of the RTFM in these systems is still a topic of controversy today. In this work, TiO2 thin films were prepared by RF sputtering onto thermally grown oxide layers on Si substrates. Cobalt implantation was performed using a metal vapor vacuum arc (MEVVA) ion source to various doses ranging from 3×1015 cm-2 to 4×1016 cm-2. Post-implantation annealing was performed in a vacuum chamber at various temperatures ranging from 400°C to 700°C for 2 hours and 4 hours. Characterization of these films as-implanted and after thermal annealing under various conditions was performed using Rutherford backscattering spectrometry, energy filtered and high-resolution transmission electron microscopy, x-ray diffractometry, x-ray photoelectron spectroscopy, and vibrating sample magnetometry. The dependence of the magnetic properties on the implantation and annealing conditions were studied in detail. Clear RTFM properties were observed. The saturation magnetic moment per implanted Co atom (MS) seems to increase with increasing dose within the implantation dose range in this study. At a fixed dose, the MS value also shows a generally increasing trend with increasing annealing temperature and annealing time. Quite a number of samples showed MS values exceeding the bulk Co value of 1.69 ìB/Co significantly and the maximum MS value observed is about 3.16 µB/Co. Such high MS values indicate that the RTFM must not come from Co clusters alone. Possible origins of the RTFM properties will be discussed in conjunction with the structural properties.

The composition, phase structure and tribological properties of H13 steel implanted with Mo

Mo ions extracted from a metal vapor vacuum arc ion source were implanted into H13 steel with a high implantation dose of 5 × 1017 cm−2 and a pulsed ion beam flux of about 300 μA cm−2. An optical interference microscopy and pin on disc apparatus investigated the wear and friction characteristics of the steel. The Mo concentration depth profile was measured by using Rutherford backscattering spectroscopy. It was observed by X-ray photoelectron spectroscopy and grazing angle X-ray diffraction that carbide of Mo appeared in the doped region. The concentration depth profile and microstructure analysis could serve to illuminate the wear resistance improvement mechanisms of the Mo implanted steel.

Surface properties and microstructure of implanted TiN films using MEVVA ion source

The PVD–TiN film was implanted with titanium and nitrogen ions and the improvement in surface wear resistance was investigated. Ti ion implantation was done using a metal vapor vacuum arc (MEVVA) ion source with an implantation dose of 2 × 10 16 ions/cm 2 and at an extraction voltage of 48 kV. The wear characteristics of the implanted samples were measured and compared with the performance of the unimplanted one by a pin-on-disc apparatus and an optical interference microscope. The structures of the samples were observed by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). A dynamic TRIM called as TRIDYN was used to calculate the concentration depth profiles of implanted ions in TiN to investigate wear resistance mechanisms. The results showed that the improved wear resistance of the TiN film was mainly due to forming of nano-order TiN crystal grains in a thick amorphous layer and the decreased local state number of Ti after Ti ion implantation.