Carbon Implantation Research Articles

In Situ Observations of Molecular CO2 Interaction on SnS2 Thin Film for Gas-Phase Photocatalytic CO2 Reduction Activity

Among the several approaches, the gas phase photocatalytic conversion of CO2 to useful fuels with the help of renewable energy sources and water vapor has attracted widespread attention. In this system, the gas-solid interaction between a CO2 molecule and a solid catalyst surface is a crucial step. However, the adsorbate-catalyst surface interaction in the gas-phase of CO2 reduction system on the surface of semiconductor photocatalysts remains unaddressed.In this report, high-quality SnS2 thin film was prepared through a chemical vapor transport process followed by controlled carbon implantation to form C-SnS2. Our material design and characterization approaches, which involve in-situ observations enabled us to correlate the adsorbate-catalyst surface interactions and their implications on photocatalytic CO2 reduction. Using in-situ dark current and in-situ Raman spectroscopy, under different gas ambient conditions, we have observed that, the C-SnS2 surface exhibited a strong affinity towards CO2 molecule and higher photon to electron conversion efficiency under light illumination. In addition, the optimized carbon implanted SnS2 sample has demonstrated more than 108 times enhancement in the CO2 conversion efficiency and about 89% product selectivity towards CH4 formation. Additional information on the mechanism of interfacial charge transfer was obtained using angle-dependent XANES, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) analysis.We anticipate that the adsorbate-catalyst surface interaction studies applied in this report can be extended to be used as a benchmark in design and material selection in the gas-phase CO2 photoreduction applications. We further expect that C-SnS2 with its promising photocatalytic performance and high affinity toward CO2 adsorption and activation; will inspire the development of new semiconductor photocatalysts by modifying it with metal or non-metal dopants towards CO2 conversion into useful products. The detail characterization and experimental results with the future perspective of this study will be presented.

High-Potential surface on zirconia ceramics for bacteriostasis and biocompatibility

Bacteria easily adhere, colonize, and form biofilm on oral implants subsequently causing periimplantation periarthritis and mechanical loosening. Previous studies show that a high potential surface on polymeric implants can achieve surface bacteriostasis without side effects. In this study, a high surface potential is introduced to zirconia ceramics to mitigate bacterial infection. Carbon and nitrogen plasma immersion ion implantation (C-PIII and N-PIII) are conducted on zirconia ceramic samples sequentially to elevate the surface potential. The surface with a high potential but without ion leaching exhibits excellent antibacterial effects against oral bacteria and little bacterial resistance is triggered. The surface also has high strength and excellent biocompatibility. The nitrogen-containing inorganic structure with high potential can actualize bacteriostasis and biocompatibility on zirconia ceramics simultaneously and this new strategy can enhance the antibacterial ability of oral implants.

Low Energy Implantation of Carbon into Elastic Polyurethane

Ion modification of polymeric materials requires gentle regimens and subsequent investigation of mechanical and deformation behavior of the surfaces. Polyurethane is a synthetic block copolymer: A fibrillar hard phase is inhomogeneoulsy distributed in a matrix of soft phase. Implantation of carbon ions into this polymer by deep oscillation magnetron sputtering (energy—0.1–1 keV and dose of ions—1014–1015 ion/cm2) forms graphene-like nanolayer and causes heterogeneous changes in structural and mechanical properties of the surface: Topography, elastic modulus and depth of implantation for the hard/soft phase areas are different. As a result, after certain treatment regimens strain-induced defects (nanocracks in the areas of the modified soft phase, or folds in the hard phase) appear on the surfaces of stretched materials. Treated surfaces have increased hydrophobicity and free surface energy, and in some cases show good deformability without any defects.

Effects of carbon and nitrogen plasma immersion ion implantation on bioactivity of zirconia.

Zirconia is considered the most promising alternative material to titanium implants. However, zirconia is a biologically inert material and its surface modification is essential to obtain efficient osseointegration. Plasma immersion ion implantation (PIII) is a controllable and flexible approach that constructs functional groups on the surface of biomaterials and enhances osteogenic ability of host osteoclast cells. Zirconia disks were randomly divided into 4 groups (n = 50/group): (1) Blank, (2) C60N0, (3) C60N6, and (4) C60N18. Carbon and nitrogen plasma immersion ion implantation on zirconia (C and N2-PIII) surface modification was completed with the corresponding parameters. When zirconia was modified by carbon and nitrogen plasma implantation, a new chemical structure was formed on the material surface while the surface roughness of the material remained unaltered. The nitrogen-containing functional groups with high potential were introduced but the bulk crystal structure of zirconia was not changed, indicating that the stability of zirconia was not affected. In vitro data showed that zirconia with high surface potential promoted adhesion, proliferation, and osteogenic differentiation of BMSCs. C60N6 was found to be superior to the other groups. Our results demonstrate that a zirconia surface modified by C and N2-PIII can introduce desirable nitrogen functional groups and create a suitable extracellular environment to promote BMSCs biological activity. Taken together, these results suggest that C and N2-PIII modified zirconia is a promising material for use in the field of medical implantation.

ERO modeling and analysis of tungsten erosion and migration from a toroidally symmetric source in the DIII-D divertor

A toroidally symmetric tungsten ring inserted in the lower outer divertor of DIII-D was exposed to 25 repeated, attached L-mode shots in reverse- configuration. Radial profiles of the W gross erosion flux inferred in situ from spectroscopic measurements of the WI line (400.9 nm) during these experiments are well reproduced by ERO-D3D simulations of carbon and tungsten impurity erosion, transport and redeposition in the outer divertor region. Tungsten gross erosion is mainly induced by physical sputtering of tungsten by carbon impurities. The outward radial transport of carbon impurities in the outer divertor is shown to be mainly governed by drifts in the sheath region. In addition, the erosion and redeposition of carbon on tungsten, induced by the implantation of carbon into tungsten modeled with the homogeneous mixed material model, increases the effective flux of carbon impurities onto the tungsten ring (carbon recycling on tungsten). The dynamics of carbon implantation in tungsten is shown to be consistent with the plasma shot duration in DIII-D. Moreover, it is shown that the localized deposition of tungsten measured experimentally in the outboard region away from the tungsten ring is caused by the long-range radial transport of tungsten impurities in the outer divertor region induced by the interplay between poloidal and radial drifts. Such experimental measurements might provide direct quantitative estimations of tungsten net erosion. The modeling and analysis of carbon and tungsten erosion and redeposition presented in this paper demonstrates that various physical mechanisms and their synergistic effects need to be taken into account to accurately describe erosion, transport and redeposition of impurities in tokamak divertors.

Orders of magnitude reduction in the thermal conductivity of polycrystalline diamond through carbon, nitrogen, and oxygen ion implantation

Despite the exceptional thermal and mechanical functionalities of diamond, its superlative properties are highly subject to the presence of point defects, dislocations, and interfaces. In this study, polycrystalline diamond is ion implanted with C3+, N3+, and O3+ ions at an energy of 16.5 MeV, producing an amorphous layer at the projected range and a damaged crystalline region between the surface and amorphous layer. Using time-domain thermoreflectance in combination with thermal penetration depth calculations based upon the multilayer heat diffusion equation, it is determined that reductions in the thermal conductivity can span nearly two orders of magnitude while still maintaining a polycrystalline structure within the regions thermally probed. Dynamical diffraction simulations of high-resolution x-ray diffraction measurements demonstrate the formation of a strained layer localized at the end of range, with much lower levels of strain near the surface. Furthermore, within the polycrystalline region above the amorphous layer, the average number of displacements-per-atom from the ion irradiation is found to be <1%, with mass impurity concentrations much less than 1%. These low defect concentrations within the thermally probed region demonstrate the remarkably large impact that dilute levels of defects from the ion implantation can have on the thermal conductivity of diamond.

Морфологическая оценка остеоинтеграции различных имплантов при замещении дефектов длинных костей (экспериментальное исследование)

Purpose To assess osseointegration of implants made of various osteoconductive materials in an animal experiment by management of a long-bone diaphysis defect complicated with chronic osteomyelitis. Materials and methods Experimental studies were conducted on 24 healthy outbred adult rabbits for six weeks. Diaphyseal defects were managed with allo-, ceramic, and carbon implants. Results and discussion With carbon material, an adhesive interaction between the implant and the maternal bone tissue was of intercalation type. Osteointegration was evidenced by the presence of microfragments of an implant in bone tissue extracted for morphological study from the peri-implant zone, with areas of numerous osteoid islets. With a ceramic implant in the defect, no signs of remodeling and osteointegration in the implant extracted for morphological examination of bone tissue were detected. In the experiment with allograft, the area of implantation was isolated by a fibrous capsule, in which individual osteo-osteoid areas were seen without typical bone structure formation, and complete bone fusion was not achieved. Conclusion Morphological data on the regeneration processes prove the advantages of a carbon nanostructured implant relative to the other osteoplastic materials used in this animal experiment.

Двухлетние результаты хирургического лечения переломов позвоночника с применением углеродных имплантатов (мультицентровое исследование)

Introduction A good alternative to bone autograft fusion is the utilization of implants produced from non-biological materials. Such implants can reduce the duration of surgery as well as tissue morbidity, while meeting the mechanical strength and osteoconductivity requirements. According to the study results,carbon is a promising material for interbody fusion because of its biocompatibility and osseointegration, as well as an elastic modulus that is close to bone tissue. Methods From 2015 to 2017 a randomized multicenter study was conducted. Three centers took part in the study: the National Medical Research Center of Traumatology and Orthopedics named after N.N. Priorov; Novosibirsk Research Institute for Traumatology and Orthopedics named after Ya.L. Tsivyan; Saint-Petersburg National Phtisiopulmonology Research Institute. One hundred thirteen patients with vertebral body fractures were included in the study and underwent surgical treatment using posterior interbody fusion. In 75 patients (66.37 %, group I) carbon-carbon implants were used, and in 38 patients (group II) – titanium cages. Patient examination was conducted using one protocol, preoperative examination methods and at 6, 12, and 24 month follow-ups, and included VAS score, SF-36 questionnaire, and ASIA scale, as well as CT examination and fusion progress assessment according to G. Tan’s classification. Results The 2-year study showed statistically significant differences between index (carbon implants) and control (titanium cages) groups. Although bone fusion progressed very slowly in the study group (in 86 % of cases no bone fusion was observed at first follow-up 6 months after surgery), the VAS and SF-36 scores were comparable in study and control groups. Discussion Carbon implants are characterized not only by high mechanical strength but also by a significant ability to osteoconductivity that allow for effective bone-carbon fusion due to their porous structure and an elastic modulus of 20–30 GPa, that is comparable to that of bone tissue. These characteristics were confirmed by radiological data (absence of implant subsidence in 38 out of 58 patients (65.51 %) at 24 month follow-up. Titanium implants with an elastic modulus of 80 GPa had a subsidence rate of 100 %.

Deeper insight into lifetime-engineering in 4H-SiC by ion implantation

Lifetime-engineering in 4H-SiC is important to obtain a low forward voltage drop in bipolar devices with high blocking voltages above 10 kV. It is known that the implantation of carbon and subsequent thermal annealing can be used to improve the minority carrier lifetime of as-grown epitaxial layers due to annihilation of carbon vacancies and, therefore, reduce the lifetime limiting defect Z1/2. In this paper, the ion implantation of other ions (N, Al, B, and As) besides carbon and their impact on minority carrier lifetime and point defect concentration are shown. Special attention is paid to the effect of ion implantation with subsequent electrical activation by high temperature annealing. A strong influence of the implantation dose and, therefore, corresponding resulting doping concentration was found. A lifetime enhancement could be found for some implanted species for higher implantation doses whereas the detrimental effect of high temperature annealing dominated at low implantation doses. The results reveal that the implantation dose and the occupied lattice sites are important parameters to achieve a lifetime enhancement. A model is presented which explains the different impacts of various implanted ions and a more detailed understanding of lifetime-engineering by ion implantation. With this knowledge, it was possible to reduce the detrimental Z1/2 defect in a large part of thick epitaxial layers with conventional shallow ion implantation and high temperature annealing. Consequently, the minority carrier lifetimes of the epitaxial layers could be enhanced.

G-Centre Formation and Behavior in a Silicon on Insulator Platform by Carbon Ion Implantation and Proton Irradiation

The interest in the G-centre is driven by reports that it can lase in silicon. To further this, the transfer of this technology from bulk silicon to a silicon-on-insulator (SOI) platform is an essential requirement to progress to lasing and optical amplification on silicon. We report on the efficient generation of the lasing G-centre in SOI substrates by proton irradiation of carbon ion implants. Following carbon implantation samples were annealed and then proton irradiated to form the G-centre and characterized by photoluminescence measurements. The temperature dependence of the emission and the behaviour of the G-centre with post proton annealing were investigated and results are compared with identical implants in control samples of bulk silicon. Overall, we find that the optically active G-centre can be up to 300% brighter and has better survivability over a wider process window in SOI than in bulk silicon.

Physicochemical fundamentals of phase formation in silicon layers implanted with oxygen and carbon

The thermodynamic and kinetic regularities of processes occurring during heat treatment in silicon layers implanted with oxygen and carbon ions have been considered. We have analyzed the regularities of silicon deformation, impurity distribution and defect formation after different annealing modes. Diffusion smearing of implanted impurities in these layers has not been observed during carbon and oxygen implantation. As-annealed carbon does not occupy sites of the silicon lattice, in contrast to the implantation behavior of other impurities, e.g. boron and phosphorus. Phase formation regularities in implanted layers during subsequent heat treatment have been analyzed. Changes in the free energy of the system during heterogeneous and homogeneous precipitate nucleation have been compared. Sequential implantation with carbon and oxygen ions has been found to initiate diffusion flows of carbon and oxygen toward the center of the ion doped layer (the uphill diffusion phenomenon). The possibility of uphill diffusion has been analyzed from the standpoints of the Onsager theory. We show that the contribution of the chemical interaction between oxygen and carbon is far greater than the entropy contribution to the diffusion flux. We have demonstrated the high efficiency of ion doping with oxygen and carbon for gettering of uncontrolled impurities from active regions of silicon structures. The efficiency of this gettering process has been assessed for epitaxial structures in which layers had been grown on silicon wafers implanted with these impurities. Uphill diffusion in the layers after double doping with carbon and oxygen has led to the formation of more defects which may provide for efficient gettering. We have found the optimal oxygen and carbon implantation dose ratio for maximal gettering efficiency.

Plasma processing of PDMS based spinal implants for covalent protein immobilization, cell attachment and spreading.

PDMS is widely used for prosthetic device manufacture. Conventional ion implantation is not a suitable treatment to enhance the biocompatibility of poly dimethyl siloxane (PDMS) due to its propensity to generate a brittle silicon oxide surface layer which cracks and delaminates. To overcome this limitation, we have developed new plasma based processes to balance the etching of carbon with implantation of carbon from the plasma source. When this carbon was implanted from the plasma phase it resulted in a surface that was structurally similar and intermixed with the underlying PDMS material and not susceptible to delamination. The enrichment in surface carbon allowed the formation of carbon based radicals that are not present in conventional plasma ion immersion implantation (PIII) treated PDMS. This imparts the PDMS surfaces with covalent protein binding capacity that is not observed on PIII treated PDMS. The change in surface energy preserved the function of bound biomolecules and enhanced the attachment of MG63 osteosarcoma cells compared to the native surface. The attached cells, an osteoblast interaction model, showed increased spreading on the treated over untreated surfaces. The carbon-dependency for these beneficial covalent protein and cell linkage properties was tested by incorporating carbon from a different source. To this end, a second surface was produced where carbon etching was balanced against implantation from a thin carbon-based polymer coating. This had similar protein and cell-binding properties to the surfaces generated with carbon inclusion in the plasma phase, thus highlighting the importance of balancing carbon etching and deposition. Additionally, the two effects of protein linkage and bioactivity could be combined where the cell response was further enhanced by covalently tethering a biomolecule coating, as exemplified here with the cell adhesive protein tropoelastin. Providing a balanced carbon source in the plasma phase is applicable to prosthetic device fabrication as illustrated using a 3-dimensional PDMS balloon prosthesis for spinal implant applications. Consequently, this study lays the groundwork for effective treatments of PDMS to selectively recruit cells to implantable PDMS fabricated biodevices.

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 High-Dose Carbon Implantation on the Phase Composition, Morphology, and Field-Emission Properties of Silicon Crystals

Effect of High-Dose Carbon Implantation on the Phase Composition, Morphology, and Field-Emission Properties of Silicon Crystals

The Effect of Temperature to the Formation of Optically Active Point-defect Complex, the Carbon G-centre in Pre-amorphised and Non-amorphised Silicon

The effect of the temperature ranging from cryogenics to room temperature were investigated on the formation of the optically-active point defect called the G-centre. The G- centre as an emissive point defect gained a lot of attention recently due to its sharp zero phonon luminescence peak at a wavelength of 1.28 μm (0.97 eV) with the evidence of lasing occurred in the structure. The emission of the G-centre is attributed to the carbon substitutional-carbon interstitial (CsCi) complex which interacts with silicon interstitials during the damage event. This complex is generated by implantation of carbon and followed by proton irradiation. Prior to the carbon implantation, two of the samples were pre-amorphised by germanium. Photoluminescence (PL) measurements were carried out at temperature ranging from 80 K up to room temperature to observe the intensity of the main peaks. The results confirm that the main peaks of point-defect centre in all of the samples including the G-centre suffer from the temperature quenching. However, the peak intensity for some of the wavelength especially the ones with high FWHM, do perform better at high temperature. The temperature quenching phenomena observed in the point-defect technique is the main problem that needs to be addressed and solved before realizing the method in the all silicon photonic system.

Corrosion properties of carbon ions implanted chromium coating prepared on CSS-42L aerospace bearing steel

In this work, carbon ions implanted chromium coating deposited on CSS-42L aerospace bearing steel by using the filtered cathodic vacuum arc deposition- metal evaporation vacuum arc duplex technique had been investigated. Film structure and properties after carbon implantation have been characterized by glancing incident XRD, AFM, SEM, TEM, AES, XPS and potentiodynamic polarization test. Carbon ions implanted chromium coating showed an increase in the pitting potential, promoting higher pitting corrosion resistance. The improvement was attributed to the reduction of surface roughness, the irradiated amorphous phase, the inert graphitic solid state carbon and the formation of nanocrystalline Cr2C and CrC.

Carrier Lifetimes in 4H-SiC Epitaxial Layers on the C-Face Enhanced by Carbon Implantation

Carrier lifetime in low carrier concentration 4H-SiC epitaxial layers grown on the C-face was enhanced by using carbon implantation and post annealing. The measured carrier lifetime increased with the thickness of the epitaxial layer and was 11.4 µs for the 150 µm thick epitaxial layer. The internal carrier lifetime was estimated as 21 µs from the dependence of the measured carrier lifetime on the epitaxial layer thickness. This value is almost comparable to the reported values of the internal carrier lifetime for the layers grown on the Si-face.

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.

Decreasing graphene synthesis temperature by catalytic metal engineering and thermal processing.

Chemical vapor deposition (CVD) from gaseous hydrocarbon sources has shown great promise for large-scale graphene growth, but the high growth temperature, typically 1050 °C, requires precise and expensive equipment and makes the direct deposition of graphene in electronic device manufacturing processes unfeasible due to the severe physical damage to substrates. Here we demonstrate a facile route to synthesize graphene by catalytic metal engineering and thermal processing. The engineered catalytic metal (copper) with carbon implantation could lower the synthetic temperature to 700 °C. And the resulting graphene shows few defects, uniform morphology and high carrier mobility, comparable to CVD graphene grown at 1050 °C. This technique could expand the applications of graphene in electronic and optoelectronic device manufacturing and is compatible with conventional microelectronics technology.

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.