Carbon Ion Implantation Research Articles

Changes in optical and structural properties of AlN after irradiation with C2+ ions of 40 keV

The effect of irradiation with C2+ ions on changes in optical and structural properties of AlN-based ceramics has been studied. The choice of C2+ ions is due to the possibility of modeling defects formation in the surface layers, as well as the formation of carbide phases in the structure during irradiation. According to XRD data, the formation of an impurity phase characteristic of the Rhombohedral Al4C3 is observed in the structure of irradiated samples, the presence of which is due to the implantation of carbon ions into the surface layers of not more than 150 nm. The decrease in the intensity of the TSL spectrum for irradiated samples is due to the appearance of defects, as well as an increase in the concentration of impurity atoms. That leads to the substitution of Al and N atoms in the structure. At the irradiation dose of 1015 ion/cm2, there is a sharp increase in the absorption spectrum and the magnitude of the optical absorption.

Reprint of “Lattice damage and expansion in RbTiOPO4 crystals induced by carbon ion implantation”

In this work, we report on the lattice damage and expansion in RbTiOPO4 induced by carbon ion implantation over a range of fluence from 2 × 1013 to 5 × 1013 ions/cm2. The samples were analyzed by means of Rutherford backscattering channeling spectrometry using both 1.4 MeV and 2.5 MeV He+ ions at a backscattering angle of 170°. The crystal lattice damage and strain of RbTiOPO4 samples with different fluencies were studied using the high resolution X-ray diffraction. The lattice expansion induced by ion implantation in the channel waveguide was measured by atomic force microscopy. The RbTiOPO4 waveguides formed by ion implantation keep perfectly transparent as shown in the transmission spectrum, indicated that few color centers remain in the ion implanted region after annealing. Surface indices nx, ny and nz of the samples as a function of ion fluence were studied. The relationship between concentration of displacements per atoms and effective refractive indices in RbTiOPO4, KTiOPO4 and KTiOAsO4 “barrier + well-enhanced” waveguides was investigated.

Decorative black coatings on titanium surfaces based on hard bi-layered carbon coatings synthesized by carbon implantation

New approaches to synthesize decorative black coatings on metallic surfaces are of significant research and commercial interest to manufacturing industries. In this work, decorative hard black coatings were deposited on a titanium surface by carbon ion implantation at ambient temperature. A 10 keV C+ beam was implanted on a Ti substrate to a fluence of 1–1.25 × 1018 C cm−2. Rutherford backscattering spectrometry and transmission electron microscopy results show that the implantation resulted in a bi-layered coating structure with a ~50 nm amorphous carbon layer at the surface followed by a ~50 nm amorphous titanium carbide intermixing layer deposited on top of a crystalline Ti surface. Raman spectroscopy confirms the formation of carbide intermixing layer and shows that the amorphous carbon layer has 15–20% sp3 content. Nanoindentation measurements show that the surface hardness of the implanted surface has increased by 72%, from 3.7 to 6.6 GPa, upon carbon implantation. Scratch tests further demonstrate a reduction in coefficient of friction in the implanted surface by 25%, signifying an improvement in wear-resistance of the coated materials. Colorimetry measurements reveal that carbon implantation reduces the luminosity of the Ti surface from 77 to 49 and chromaticity from 4.67 to 1.36, confirming incorporation of black color on Ti surface. The results demonstrate that C implantation onto a Ti surface at high fluence results in a black coating with high surface hardness and wear-resistance that can be employed in decorative surface applications for manufacturing industries.

Effect of intense electron and ion irradiation on optical absorption of boron carbide thin films

ABSTRACTThe energetic characteristics of growth and radiation defects (RDs) in boron carbide films deposited by reactive magnetron sputtering on a steel substrate and irradiated with powerful electron and pulsed ion beams were investigated. The relationship between the characteristics of point RDs, the degree of distortion of the electronic structure and the characteristics of interband and exponential absorption was established. The absorption spectra of the films were due to electronic transitions between the defects energy states localized in the band gap and interband transitions. The stability of characteristics to electron irradiation was due to the high concentration of growth defects, distributed along the boundaries between the structural fragments. Short-pulse implantation of carbon ions stimulates partial annealing of intrinsic RDs and their redistribution and formation of thermally stable complexes from defects. Boron carbide films significantly exceed the radiation resistance of sodium calcium silicate glass, but are slightly inferior to the films of aluminum and silicon nitrides, obtained by magnetron deposition.

Enhancement of superconducting parameters of MgB2 by low energy carbon ion implantation

The aim of work is to study the effects of carbon ion implantation on enhancement of superconducting properties of MgB2. Pure MgB2 bulk samples are irradiated by carbon ion beam of energy 40 keV (beam current 1 µA) at different fluences. After irradiation, there is enhancement in superconducting properties viz., critical current density (Jc), critical magnetic field (Hc2), comparing to pristine sample. Estimated with Ginzburg-Landau theory method at zero kelvin, the critical magnetic field Hc2(0) for irradiated sample shows an increase of 47 T than that of 38 T reported for pristine sample. There is also a four times increase in Jc after implantation. Improvement in grain connectivity with ion fluence is found in surface morphological studies. Raman spectroscopic studies show a shift in resonance peak related with E2g phonon modes after irradiation. This shifting is caused due to improvement in scattering and alteration of Fermi surface in implanted samples. These results are explained in correlation with the lattice disorder.

Synthesis of amorphous hydrogenated carbon (a-C:H) films on Germanium by the use of the linear anode layer source

A method for the synthesis of amorphous hydrogenated carbon (a-C:H) films with high adhesion is proposed, based on the implantation of carbon ions into a monocrystalline germanium substrate. The flow of ionized carbon was created by an anode layer ions source in crossed electric and magnetic fields. Propane gas was introduced into the area with an increased electron concentration. The gas flow rate varied from 4.5 to 10 sccm. Ionized fragments of propane, including carbon ions, were accelerated by the electric field and deposited on the substrate. At the same time, ionized carbon penetrated into the surface layer of germanium, creating an interlayer that provides film’s adhesion. The substrate was argon sputtered for several minutes before the deposition. The synthesis of the coating includes two-stage process. At the first stage, the films were deposited by an ion beam with a mean energy of about 1.6 keV for 0.5 to 1 hour to obtain an adhesive interlayer. Then the mean energy of the beam was reduced to 0.3 keV and the deposition continued for 3.5 hours to maintain the hardness of the coatings. The deposition rate was changed from 0.3 to 1.3 Å/sec. Adhesion, the bond between the coating and the substrate is high. There is no detachment of the film while scratching by diamond Berkovich nanoindent with a load of up to 50 mN. The maximum film hardness is 20 GPa. Spectroscopic studies have shown the maximum transmission of germanium with a single side a-C:H coating is 67% at a wavelength of 5 μm, while bare substrate transmission is 51%. The results of the work can be applied in the creation of protective antireflective coatings of optical systems, the creation of medical implants and mechanical devices.

Carbon doping controlled thermoluminescent defect centers in nanoporous alumina for ion beam dosimetry

The flexibility of amorphous anodized alumina (AAO) in developing radiation dosimeter for hadron therapy is reported by controlled carbon ion implantation, followed by thermoluminescence (TL) measurements. The efficacy of amorphous AAO in controlling TL sensitivity is found to be governed by an increase in F+ defect centers as a function of carbon concentration, as revealed from the close resemblance of the trend in photoluminescence intensity. Moreover, its nanoporous structure is demonstrated to be advantageous for defect engineering due to the increase in the surface-to-volume ratio. Detailed X-ray photoelectron spectroscopy analysis suggests the formation of F+ centers by substituting Al3+ ions with C2+ in the vicinity of oxygen vacancies, where depth-dependent study showed the evolution of conducting channels owing to sp2 hybridized C–C bonding, leading to a differential charging effect. This work provides a direction to tune nanoporous AAO in its amorphous form for future ion beam dosimetry.

Influence of carbon ion implantation energy on aluminum carbide precipitation and electrochemical corrosion resistance of aluminum

The effects of varying carbon ions (C+) implantation energies on Aluminum Carbide (Al4C3) precipitation, surface morphology and electrochemical corrosion resistance of aluminum (Al) were evaluated. The Al samples were implanted with C+ of different energies of 0.25, 0.5, 1, 2, and 4 MeV at a constant dose of 1 × 1015 ions/cm2. The X-rays diffraction (XRD) and field emission scanning electron microscope (FESEM) results showed Al4C3 precipitates in the ion-implanted Al which were decreased at higher implantation energies (≥1 MeV). The decrease in Al4C3 precipitation was attributed to the lower chemical reactivity of C+ with Al due to ion-induced lattice defects. The Al surface became rough, and micro-cracks appeared on it as the ion energy increased above 0.25 MeV. The electrochemical corrosion rate of Al decreased from 469.9 mpy to 70.32 mpy after C+ implantation at 0.25 MeV. However, the corrosion rate increased with increasing ion energy above 0.25 MeV. This changes in corrosion rate were elucidated on the basis of Al4C3 precipitation and lattice defects in Al created by C+ implantation. The SEM analysis of electrochemically tested samples indicated lower pitting in the sample implanted with 0.25 MeV ions as compared to those implanted with higher energy.

Effect of the Distribution of the Radiation Defect on the Field-Emission Properties of Silicon Crystals

The correlated regularities of the variations in the structural and phase composition and morphological and field-emission characteristics of the surface-structured р- and n-Si crystals upon stepwise highdose ion-beam carbon processing are studied. It is shown that the stepwise high-dose ion implantation of carbon atoms into the surface of silicon wafers structured using nonlithographic carbon mask coatings makes it possible to reduce field-emission thresholds and increase the densities of the maximum field-emission currents by more than two orders of magnitude relative to the values for emitter arrays fabricated using traditional microelectronic technologies. The physicochemical mechanisms responsible for modifying the surface properties of silicon structures upon carbon ion implantation are discussed.

Lattice damage and expansion in RbTiOPO4 crystals induced by carbon ion implantation

In this work, we report on the lattice damage and expansion in RbTiOPO4 induced by carbon ion implantation over a range of fluence from 2 × 1013 to 5 × 1013 ions/cm2. The samples were analyzed by means of Rutherford backscattering channeling spectrometry using both 1.4 MeV and 2.5 MeV He+ ions at a backscattering angle of 170°. The crystal lattice damage and strain of RbTiOPO4 samples with different fluencies were studied using the high resolution X-ray diffraction. The lattice expansion induced by ion implantation in the channel waveguide was measured by atomic force microscopy. The RbTiOPO4 waveguides formed by ion implantation keep perfectly transparent as shown in the transmission spectrum, indicated that few color centers remain in the ion implanted region after annealing. Surface indices nx, ny and nz of the samples as a function of ion fluence were studied. The relationship between concentration of displacements per atoms and effective refractive indices in RbTiOPO4, KTiOPO4 and KTiOAsO4 “barrier + well-enhanced” waveguides was investigated.

Study on the formation of graphene by ion implantation on Cu, Ni and CuNi alloy

This study identifies the details for direct synthesis of graphene by carbon ion implantation on Cu, Ni and CuNi alloy. Firstly, diffusion and concentration of carbon atoms in Cu and Ni are estimated separately. The concentrations of carbon atoms near the surfaces of Cu and Ni after carbon ion implantation and subsequent thermal annealing were correlated with the number of atoms and with the coverage or thickness of graphene. Systematic experiments showed that the Cu has higher carbon diffusivity and graphene coverage than Ni but higher temperatures and longer annealing times are required to synthesize graphene, similar to those in chemical vapor deposition method. The CuNi system shows better graphene coverage and quality than that on a single metal catalyst even after a short annealing time, as it has larger carbon diffusivity and lower carbon solubility than Ni and shows lower activation energy than Cu.

High near-infrared transmittance and waveguide structures in polycrystalline ZnSe by carbon and proton implantation combined with photolithography

We report on near-infrared (NIR) waveguide structures in polycrystalline ZnSe using the carbon ion implantation technique combined with standard lithography. High NIR transmittance is observed by the absorption spectra before and after carbon and proton implantation at room temperature. Two half-Gaussian curves are used to reconstruct the refractive index profile of the waveguides at a wavelength of 1539 nm. The results show that the numerically simulated mode by the finite difference beam propagation method (FD-BPM) is in good agreement with the experimental data by end-facet setup, which exhibits a high potential for designable NIR waveguide devices in polycrystalline ZnSe by carbon ion implantation.

Optical Planar Waveguides Fabricated by Using Carbon Ion Implantation in Terbium Gallium Garnet

Optical planar waveguides in terbium-gallium-garnet (TGG) crystals are promising photonic devices, particularly for optical isolators and rotators. In this work, to the best of our knowledge, we report on the fabrication and the characterization of TGG waveguides for the first time. The fabrication procedure involved carbon ion implantation at an energy of 6.0 MeV and a fluence of 5.0×1014 ions/cm2. The effective refractive indices of the propagation modes in the carbonimplanted waveguide were measured by using the prism-coupling technique. The profile of the refractive index and the distribution of the near-field intensity were calculated by using the reflectivity calculation method and the finite-difference beam propagation method, respectively. The carbon-implanted TGG waveguide is considered to be a candidate for a magneto-optical photonic device.

Optical waveguides in fluoride lead silicate glasses fabricated by carbon ion implantation

The carbon ion implantation with energy of 4.0 MeV and a dose of 4.0×1014 ions/cm2 is employed for fabricating the optical waveguide in fluoride lead silicate glasses. The optical modes as well as the effective refractive indices are measured by the prism coupling method. The refractive index distribution in the fluoride lead silicate glass waveguide is simulated by the reflectivity calculation method (RCM). The light intensity profile and the energy losses are calculated by the finite-difference beam propagation method (FD-BPM) and the program of stopping and range of ions in matter (SRIM), respectively. The propagation properties indicate that the C2+ ion-implanted fluoride lead silicate glass waveguide is a candidate for fabricating optical devices.

Formation of graphitic and diamond-like carbon by low energy carbon ion implantation on c plane sapphire substrate

The present work reports the effect of 200 keV carbon ion implantation on the c-axis sapphire with different fluences: 4 × 1015, 8 × 1015 and 1.6 × 1016 ions/cm2. The electronic and nuclear energy losses and projected range were calculated using the Stopping and Range of Ions in Matter software. The Raman studies of as-implanted and post-implantation annealed samples showed the signatures of graphitic and diamond-like carbon materials. The structural studies were carried out using X-ray diffraction which showed the presence of carbon in different phases. The optical properties of the samples were studied using the room temperature Photoluminescence which confirms the formation of F-type color centers due to microstructural changes. The morphological studies by Atomic Force Microscopy revealed the surface modification in the samples. The Hall measurements were carried out on carbon ion implanted sapphire substrate and analyzed. The Hall measurements confirmed that the insulating c-sapphire becomes conducting after carbon ion implantation and subsequent annealing.

Optical planar waveguides in photo-thermal-refractive glasses fabricated by single- or double-energy carbon ion implantation

Ion implantation has demonstrated to be an efficient and reliable technique for the fabrication of optical waveguides in a diversity of transparent materials. Photo-thermal-refractive glass (PTR) is considered to be durable and stable holographic recording medium. Optical planar waveguide structures in the PTR glasses were formed, for the first time to our knowledge, by the C3+-ion implantation with single-energy (6.0 MeV) and double-energy (5.5+6.0 MeV), respectively. The process of the carbon ion implantation was simulated by the stopping and range of ions in matter code. The morphologies of the waveguides were recorded by a microscope operating in transmission mode. The guided beam distributions of the waveguides were measured by the end-face coupling technique. Comparing with the single-energy implantation, the double-energy implantation improves the light confinement for the dark-mode spectrum. The guiding properties suggest that the carbon-implanted PTR glass waveguides have potential for the manufacture of photonic devices.

Влияние имплантации ионов углерода на адгезию и свойства аморфных углеродных пленок на германии

Влияние имплантации ионов углерода на адгезию и свойства аморфных углеродных пленок на германии

Waveguiding structures in Yb3+-doped phosphate glasses by double-energy proton and single-energy carbon-ion implantations

We report on the construction of waveguiding structures operating at 632.8 nm in the Yb3+-doped phosphate glass by two different techniques: carbon-ion implantation with a single-implant at an energy of 6.0 MeV and a dose of 5.0 × 1014 ions cm−2, and proton implantation with a double-implant of energies of (500 + 550) keV and doses of (1 + 2) × 1016 ions cm−2. The annealing treatments were performed at different temperatures ranging from 260 °C to 460 °C at internals of 50 °C. For the proton-implanted waveguide, the m-line spectrum and the refractive index profile were studied by a modal 2010 prism coupler and a reflectivity calculation method, respectively. The near field patterns in the both cases were recoded by an end-fire coupling system. The carbon- and proton-implanted Yb3+-doped phosphate glass waveguides can propagate guided modes after the continuous annealing, suggesting the applicability in the development of photonics devices.

Surface Carbonization of GaN and the Related Structure Evolution during the Annealing Process**Supported by the National Natural Science Foundation of China under Grant No 51402013, the National Key Research and Development Program of China under Grant No 2016YFE0133200, and the European Union’s Horizon 2020 Research and Innovation Staff Exchange Scheme under Grant No 734578.

To explain the stabilization mechanism of the carbon-ion-implanted GaN under the diamond growth environment, the luminescence characteristics and structure evolution correlative with sites’ carbon atoms located for high-fluence carbon-ion-implanted GaN are discussed. GaN is implanted with carbon ion using fluence of 2 × 1017 cm−2 and energy of 45 keV. Then the implanted samples are annealed at 800°C for 20 min and 1 h under the N2 atmosphere. The luminescence characteristics of carbon-ion-implanted GaN are evaluated by photoluminescence spectrum at wavelength 325 nm. The lattice damage of GaN is characterized by Raman spectrum and the corresponding vacancy-defect evolution before and after annealing is measured by slow positron annihilation. The results show that most of the carbon atoms will be located at the interstitial sites after carbon ion implantation due to the weak mobility. As the implanted samples are annealed, strong yellow luminescence is emitted and the vacancies for Ga (VGa) are reduced resulting from the migration of interstitial carbon (Ci) and formation of complexes (CGa and/or CGa-Ci) between them. As the annealing time is prolonged, the carbon ions accommodated by the vacancies are saturated, vacancy clusters with carbon atoms appear and the concentration of CGa diminishes, which will have an adverse effect on the diamond film nucleation and growth.

Влияние высокодозной имплантации углерода на фазовый состав, морфологию и автоэмиссионные свойства кристаллов кремния

AbstractThe study of high-dose carbon-ion implantation without post-process annealing reveals significant modification of the morphology, surface-layer phase composition, and field-emission properties of silicon wafers. The effect of the electrical conductivity type on the evolution of the silicon-crystal surface morphology, upon a variation in the irradiation dose, and a high content of diamond-like phases in the region of microprotrusions at the maximum dose regardless of the electrical conductivity type are found. It is demonstrated that the high-dose implantation of carbon in silicon wafers with a pre-structured surface increases the maximum density of field-emission currents by more than two orders of magnitude.