Ion implantation induced damage in GaSb and its removal by rapid thermal annealing(RTA)have been investigated by Raman spectroscopy.The evolution of the Raman modes as a function of implantation fluence,annealing temp...Ion implantation induced damage in GaSb and its removal by rapid thermal annealing(RTA)have been investigated by Raman spectroscopy.The evolution of the Raman modes as a function of implantation fluence,annealing temperature and time has been analyzed.Results indicate that a lattice quality that is close to as-grown GaSb has been obtained by annealing the implanted samples at 500℃for 45 s.However,consequent surface analyses by scanning electron microscope(SEM)and atomic force microscope(AFM)show that a heavily perturbed layer contains voids due to the outdifiusion of Sb atoms on the surface remains.Mechanism of the damage recovery and the structure of the implanted layer are discussed based on the experimental results.展开更多
Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for re...Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for reducing the detection limit of high-purity germanium detectors and scintillator calorimeters,which are widely applied in dark matter and 0υββdetection experiments.The traditional adhesive bonding method between PTFE and copper is not conducive to working in liquid nitrogen and extremely low-temperature environments.To avoid adhesive bonding,PTFE must be processed for surface metallization owing to the mismatch between the PTFE and copper conductive layer.Low-background PTFE matrix composites(m-PTFE)were selected to improve the electrical and mechanical properties of PTFE by introducing SiO_(2)/TiO_(2) particles.The microstructures,surface elements,and electrical properties of PTFE and m-PTFE were characterized and analyzed following ion implantation.PTFE and m-PTFE surfaces were found to be broken,degraded,and cross-linked by ion implantation,resulting in C=C conjugated double bonds,increased surface energy,and increased surface roughness.Comparably,the surface roughness,bond strength,and conjugated double bonds of m-PTFE were significantly more intense than those of PTFE.Moreover,the interface bonding theory between PTFE and the metal copper foil was analyzed using the direct metallization principle.Therefore,the peel strength of the optimized electronic substrates was higher than that of the industrial standard at extremely low temperatures,while maintaining excellent electrical properties.展开更多
A nano-twinned microstructure was found in amorphous SiC after high-temperature annealing.Grazing incidence x-ray diffraction,high-resolution transmission electron microscopy,and electron diffraction were performed to...A nano-twinned microstructure was found in amorphous SiC after high-temperature annealing.Grazing incidence x-ray diffraction,high-resolution transmission electron microscopy,and electron diffraction were performed to characterize the microstructure and phase transition in the recrystallization layer.After 1500℃or 2-h annealing,3C-SiC grains and numerous stacking faults on the{111}planes were visible.Some 3C-SiC grains have nano-twinned structure with{011}planes.Between the nano-twinned 3C-SiC grains,there is a stacking fault,indicating that the formation mechanisms of the nano-twinned structure are related to the disorder of Si atoms.The increase in the twin thickness with increasing annealing temperature demonstrates that the nano-twinned structure can sink for lattice defects,in order to improve the radiation tolerance of SiC.展开更多
Structural and morphological changes as well as corrosion behavior of N+implanted Al in 0.6 M NaCl solution as function of N+fluence are investigated.The x-ray diffraction results confirmed AlN formation.The atomic fo...Structural and morphological changes as well as corrosion behavior of N+implanted Al in 0.6 M NaCl solution as function of N+fluence are investigated.The x-ray diffraction results confirmed AlN formation.The atomic force microscope(AFM)images showed larger grains on the surface of Al with increasing N+fluence.This can be due to the increased number of impacts of N+with Al atoms and energy conversion to heat,which increases the diffusion rate of the incident ions in the target.Hence,the number of the grain boundaries is reduced,resulting in corrosion resistance enhancement.Electrochemical impedance spectroscopy(EIS)and polarization results showed the increase of corrosion resistance of Al with increasing N+fluence.EIS data was used to simulate equivalent electric circuits(EC)for the samples.Strong dependence of the surface morphology on the EC elements was observed.The scanning electron microscope(SEM)analysis of the samples after corrosion test also showed that the surfaces of the implanted Al samples remain more intact relative to the untreated Al sample,consistent with the EIS and polarization results.展开更多
The retention and release of deuterium in W–2%Y2O3 composite materials and commercially pure tungsten after they have been implanted by deuterium plasma(flux ~ 3.71 × 1021 D/m2·s, energy ~ 25 eV, and fluenc...The retention and release of deuterium in W–2%Y2O3 composite materials and commercially pure tungsten after they have been implanted by deuterium plasma(flux ~ 3.71 × 1021 D/m2·s, energy ~ 25 eV, and fluence up to 1.3 × 1026D/m2)are studied. The results show that the total amount of deuterium released from W–2%Y2O3 is 5.23 × 1020 D/m2(2.5 K/min),about 2.5 times higher than that from the pure tungsten. Thermal desorption spectra(TDS) at different heating rates(2.5 K/min–20 K/min) reveal that both W and W–2%Y2O3 have two main deuterium trapped sites. For the low temperature trap, the deuterium desorption activation energy is 0.85 eV(grain boundary) in W, while for high temperature trap, the desorption activation energy is 1.57 eV(vacancy) in W and 1.73 eV(vacancy) in W–2%Y2O3.展开更多
The enhanced diffusion in materials under irradiation plays an important role in the long-term microstructural evolution. In this work, the self-ion irradiation in nickel was used as a model system to study the effect...The enhanced diffusion in materials under irradiation plays an important role in the long-term microstructural evolution. In this work, the self-ion irradiation in nickel was used as a model system to study the effect of radiation-enhanced diffusion on the implanted ion profiles. Initially, the depth profiles of vacancies and implanted ions for nickel self-ion irradiation with ion energies up to 15 MeV were computed by the high-efficiency Monte Carlo code IM3D(Irradiation of Materials in 3 D). The results are in good agreement with those predicted by SRIM(Stopping and Range of Ions in Matter).Then, diffusion coefficients as functions of temperature and damage rate were obtained, and the depth-dependent diffusion coefficients at various temperatures and damage rates were also illustrated. For this purpose, we used a temperature-dependent effective sink concentration for nickel, which was estimated from the available experimental investigations on the damage structures of irradiated nickel. At length, case studies on the time evolution of implanted ion profiles under the condition of nickel selfirradiation were performed and discussed based on Fick’s second law. The results help to understand the fundamental diffusion properties in ion irradiation, especially under higher-dose irradiation.展开更多
Biodegradable stents made of magnesium(Mg)and its alloys have been developed to minimize persistent inflammation or in-stent restenosis,which are the main problems for permanent stents.However,their rapid corrosion be...Biodegradable stents made of magnesium(Mg)and its alloys have been developed to minimize persistent inflammation or in-stent restenosis,which are the main problems for permanent stents.However,their rapid corrosion behavior under physiological conditions leads to poor vascular compatibility and premature structural failure,which remains an important unsolved clinical problem.Herein,we demonstrate a new strategy for solving this problem by combining poly(ether imide)(PEI)coating and subsequent tantalum(Ta)ion implantation.The PEI coating covers the whole surface of the Mg stent uniformly via a spray coating technique and provides Mg with superior corrosion resistance and stable sirolimus-carrying ability.Ta ion implantation is conducted by a sputtering-based plasma immersion ion implantation technique only onto the luminal surface of the PEI-coated Mg stent.Its extremely short processing time(<30 s)permits preservation of the PEI coating’s corrosion protection ability and sirolimus loading characteristics.In addition,a Ta-implanted skin layer that forms on the topmost surface of the PEI coating plays an effective role in not only preventing a rapid release of sirolimus from the surface but also improving the PEI coating’s surface hydrophilicity.Based on in vitro cellular response and blood compatibility tests,Ta ion implantation leads to the improvement of endothelial cell adhesion/proliferation and suppression of platelet adhesion/activation regardless of sirolimus loading.These results indicate that the combination of PEI coating and Ta ion implantation has significant innovative potential to provide excellent vascular compatibility and prevent in-stent restenosis and thrombosis.展开更多
Problems in metal-on-metal (MoM) hip replacement systems still persist due to high wear rates, low corrosion resistance and release of toxic ions and nanoparticles. As a consequence of these effects, failure, infectio...Problems in metal-on-metal (MoM) hip replacement systems still persist due to high wear rates, low corrosion resistance and release of toxic ions and nanoparticles. As a consequence of these effects, failure, infections, loosening or bone resorption is the typical problems in the hip prosthesis. In order to reduce failure due to corrosion and/or releasing ions and particles, this study presents some works in a novel nanoscale surface modification of cobalt-chromium alloy (CoCr) for obtaining improved surface conditions in these alloys for these applications. Improving corrosion resistant of these alloys and achieving a low wear rate are possible to reduce the total released ions and particles released from the surface of this material. According to it, three different treatments using oxygen at temperatures of 300°C, 350°C and 400°C were carried out by plasma immersion ion implantation technique (PI3). X-ray diffraction (XRD) analysis shows an increase in the formation of chromium oxides in the outer surface of the CoCr alloy. It allows improving in corrosion resistant in CoCr alloys. Moreover, total quantity of released Co, Cr and Mo ions have been reduced. Wear rate studies showed a very similar behaviour after the treatments in relation to untreated CoCr alloy and release rate from the treated surface of CoCr alloys was reduced in comparison with untreated CoCr alloy.展开更多
Introducing heteroatoms and defects is a significant strategy to improve oxygen evolution reaction(OER)performance of electrocatalysts.However,the synergistic interaction of the heteroatom and defect still needs furth...Introducing heteroatoms and defects is a significant strategy to improve oxygen evolution reaction(OER)performance of electrocatalysts.However,the synergistic interaction of the heteroatom and defect still needs further investigations.Herein,we demonstrated an oxygen vacancy-rich vanadium-doped Co_(3)O_(4)(V-Ov-Co_(3)O_(4)),fabricated by V-ion implantation,could be used for high-efficient OER catalysis.X-ray photoelectron spectra(XPS)and density functional theory(DFT)calculations show that the charge density of Co atom increased,and the reaction barrier of reaction pathway from O∗to HOO∗decreased.V-Ov-Co_(3)O_(4) catalyst shows a low overpotential of 329 mV to maintain current density of 10 mA·cm^(−2),and a small Tafel slope of 74.5 mV·dec^(−1).This modification provides us with valuable perception for future design of heteroatom-doped and defect-based electrocatalysts.展开更多
Chemical disorder on the surface and lattice strain in GaN implanted by Fe^(10+)ions are investigated.In this study,3-MeV Fe^(10+)ions fluence ranges from 1×10^(13)ions/cm^(2)to 5×10^(15)ions/cm^(2)at room t...Chemical disorder on the surface and lattice strain in GaN implanted by Fe^(10+)ions are investigated.In this study,3-MeV Fe^(10+)ions fluence ranges from 1×10^(13)ions/cm^(2)to 5×10^(15)ions/cm^(2)at room temperature.X-ray photoelectron spectroscopy,high-resolution x-ray diffraction,and high-resolution transmission electron microscopy were used to characterize lattice disorder.The transition of Ga-N bonds to oxynitride bonding is caused by ion sputtering.The change of tensile strain out-of-plane with fluence was measured.Lattice disorder due to the formation of stacking faults prefers to occur on the basal plane.展开更多
In this paper,the ESD discharge capability of GGNMOS(gate grounded NMOS)device in the radiation-hardened 0.18μm bulk silicon CMOS process(Rad-Hard by Process:RHBP)is optimized by layout and ion implantation design.Th...In this paper,the ESD discharge capability of GGNMOS(gate grounded NMOS)device in the radiation-hardened 0.18μm bulk silicon CMOS process(Rad-Hard by Process:RHBP)is optimized by layout and ion implantation design.The effects of gate length,DCGS and ESD ion implantation of GGNMOS on discharge current density and lattice temperature are studied by TCAD and device simulation.The size of DCGS,multi finger number and single finger width of ESD verification structures are designed,and the discharge capacity and efficiency of GGNMOS devices in ESD are characterized by TLP test technology.Finally,the optimized GGNMOS is verified on the DSP circuit,and its ESD performance is over 3500 V in HBM mode.展开更多
To investigate the effect of dislocation structures on the initial formation stage of helium bubbles, molecular dynamics(MD) simulations were used in this study. The retention rate and distribution of helium ions with...To investigate the effect of dislocation structures on the initial formation stage of helium bubbles, molecular dynamics(MD) simulations were used in this study. The retention rate and distribution of helium ions with 2 ke V energy implanted into silicon with dislocation structures were studied via MD simulation. Results show that the dislocation structures and their positions in the sample affect the helium ion retention rate. The analysis on the three-dimensional distribution of helium ions show that the implanted helium ions tend to accumulate near the dislocation structures. Raman spectroscopy results show that the silicon substrate surface after helium ion implantation displayed tensile stress as indicated by the blue shift of Raman peaks.展开更多
The n-type PbTe doped with 0.05 mol fraction Pbl2 was hot-pressed, and the sintered samples were implanted by Sn+ ions at 200 KeV with doses of 6×1016 and 1×1017 ions/cm2. The effect of Sn+ implantation on t...The n-type PbTe doped with 0.05 mol fraction Pbl2 was hot-pressed, and the sintered samples were implanted by Sn+ ions at 200 KeV with doses of 6×1016 and 1×1017 ions/cm2. The effect of Sn+ implantation on thermoelectric properties was then investigated. The results show that Sn+ ion implantation can modify thermoelectric properties of the n-type PbTe and greatly improve the dimensionless展开更多
The defect evolution in InP with the 75 keV H^(+)and 115 keV He^(+)implantation at room temperature after subsequent annealing has been investigated in detail.With the same ion implantation fluence,the He^(+)implantat...The defect evolution in InP with the 75 keV H^(+)and 115 keV He^(+)implantation at room temperature after subsequent annealing has been investigated in detail.With the same ion implantation fluence,the He^(+)implantation caused much broader damage distribution accompanied by much higher out-of-plane strain with respect to the H^(+)implanted InP.After annealing,the H^(+)implanted InP did not show any blistering or exfoliation on the surface even at the high fluence and the H2 molecules were stored in the heterogeneously oriented platelet defects.However,the He molecules were stored into the large bubbles which relaxed toward the free surface,creating blisters at the high fluence.展开更多
Oxygen ions(O;)were implanted into fused silica at a fixed fluence of 1×10^(17) ions/cm^(2) with different ion energies ranging from 10 ke V to 60 ke V.The surface roughness,optical properties,mechanical properti...Oxygen ions(O;)were implanted into fused silica at a fixed fluence of 1×10^(17) ions/cm^(2) with different ion energies ranging from 10 ke V to 60 ke V.The surface roughness,optical properties,mechanical properties and laser damage performance of fused silica were investigated to understand the effect of oxygen ion implantation on laser damage resistance of fused silica.The ion implantation accompanied with sputtering effect can passivate the sub-/surface defects to reduce the surface roughness and improve the surface quality slightly.The implanted oxygen ions can combine with the structural defects(ODCs and E′centers)to reduce the defect densities and compensate the loss of oxygen in fused silica surface under laser irradiation.Furthermore,oxygen ion implantation can reduce the Si-O-Si bond angle and densify the surface structure,thus introducing compressive stress in the surface to strengthen the surface of fused silica.Therefore,the laser induced damage threshold of fused silica increases and the damage growth coefficient decreases when ion energy up to30 ke V.However,at higher ion energy,the sputtering effect is weakened and implantation becomes dominant,which leads to the surface roughness increase slightly.In addition,excessive energy aggravates the breaking of Si-O bonds.At the same time,the density of structural defects increases and the compressive stress decreases.These will degrade the laser laser-damage resistance of fused silica.The results indicate that oxygen ion implantation with appropriate ion energy is helpful to improve the damage resistance capability of fused silica components.展开更多
Despite anionic doping has been widely implemented to increase the visible light activity of TiO_(2),it often gives rise to a dramatical anodic shift in current onset potential.Herein,we show an effective method to ac...Despite anionic doping has been widely implemented to increase the visible light activity of TiO_(2),it often gives rise to a dramatical anodic shift in current onset potential.Herein,we show an effective method to achieve the huge cathodic shift of TiO_(2) photoanode with significantly enhanced visible light photo-electrochemical activity by nitrogen/cobalt coimplantation.The nitrogen/cobalt co-doped TiO_(2)nanorod arrays(N/Co-TiO_(2))exhibit a cathodic shift of 350 mV in onset potential relative to only nitrogen-doped TiO_(2)(N-TiO_(2)).Moreover,the visible-light(λ>420 nm)photocurrent density of N/Co-TiO_(2) reaches 0.46 mA/cm^(2),far exceeding 0.07 mA/cm^(2) in N-TiO_(2)at 1.23 V versus reversible hydrogen electrode(RHE).Systematic characterization studies demonstrate that the enhanced photo-electrochemical performance can be attributed to the surface synergic sputtering of high-energy nitrogen/cobalt ions.展开更多
The bifacial n-PERT(Passivated Emitter Rear Totally diffused)solar cells were fabricated using a simplified process in which the activation of ion-implanted phosphorus and boron diffusion were performed simultaneously...The bifacial n-PERT(Passivated Emitter Rear Totally diffused)solar cells were fabricated using a simplified process in which the activation of ion-implanted phosphorus and boron diffusion were performed simultaneously in a high-temperature process.For further efficiency improvement,the rear side doping level was regulated by applying two different implantation doses and the chemical etching step of boron rich layer(BRL)was added,and their effects on cell performance were investigated.The solar cells average efficiency reaches 20.35%with a bifaciality factor of 90%by optimizing rear side doping level,which can be explained by the decrease of Auger recombination.And it is further enhanced to 20.74%by removing the front side BRL due to the improvement of surface passivation and bulk lifetime.The improved fabrication process possesses the advantages of low complexity and cost and high cell efficiency and bifaciality factor which could provide a promising way to the commercial production of bifacial n-PERT solar cells.展开更多
The composition and structure of Ti 6Al 4V alloy plasma based ion implanted with nitrogen was investigated.The nitrogen depth distribution shows more antiballistic with distribution peak heightened with increased impl...The composition and structure of Ti 6Al 4V alloy plasma based ion implanted with nitrogen was investigated.The nitrogen depth distribution shows more antiballistic with distribution peak heightened with increased implantation time(dose),and more like a parabola at the low implantation pulse voltage.When implantation pulse voltage is increased,the implantation depth increased with the nitrogen distribution peak being deepened,widened and lowered somewhat.TiN,TiN+Ti 2N,or Ti 2N second phases were formed in the implanted layer.The relative percentage of nitrogen content in the form of TiN increases when going deeper into the implanted(TiN formed) layer.The increase of implantation pulse width and/or time is favourable for the formation of TiN rather than Ti 2N.It is unfavourable for formation of any nitrides when implantation pulse voltage is decreased to 30kV or less.Tiny crystalline particles (made mainly of Ti 2N and a smaller percentage of TiO 2 phases) of regular shapes such as triangle and tetragon, etc .(about 20 nm) are found distrbuted dispersively in the near surface region of samples implanted at the high implantation pulse voltage (75kV).展开更多
Thermal annealing and laser irradiation were used to study the activation rate of phosphorus in silicon after ion implantation.The activation rate refers to the ratio of activated impurity number to the total impurity...Thermal annealing and laser irradiation were used to study the activation rate of phosphorus in silicon after ion implantation.The activation rate refers to the ratio of activated impurity number to the total impurity number in the sample.After injecting phosphorus with the dose and energy(energy=55 keV,dose=3×10^(15) cm^(-2)),the samples were annealed at different temperatures,and laser irradiation experiments were performed after annealing.The experimental results showed that the activation rate of phosphorus was the highest at 850℃,and the highest activation rate was 67%.Upon femtosecond laser irradiation samples after thermal annealing,while keeping the crystalline silicon surface without damage,the activation rate was improved.When the energy-flux density of the femtosecond laser was 0.65 kJ/cm2,the activation rate was the highest,increasing from 67%to 74.81%.展开更多
We show the structural and optical properties of non-polar a-plane GaN epitaxial films modified by Si ion implantation.Upon gradually raising Si fluences from 5×10^(13)cm^(-2)to 5×10^(15)cm^(-2),the n-type d...We show the structural and optical properties of non-polar a-plane GaN epitaxial films modified by Si ion implantation.Upon gradually raising Si fluences from 5×10^(13)cm^(-2)to 5×10^(15)cm^(-2),the n-type dopant concentration gradually increases from 4.6×10^(18)cm^(-2)to 4.5×10^(20)cm^(-2),while the generated vacancy density accordingly raises from 3.7×10^(13)cm^(-2)to 3.8×10^(15)cm^(-2).Moreover,despite that the implantation enhances structural disorder,the epitaxial structure of the implanted region is still well preserved which is confirmed by Rutherford backscattering channeling spectrometry measurements.The monotonical uniaxial lattice expansion along the a direction(out-of-plane direction)is observed as a function of fluences till 1×10^(15)cm^(-2),which ceases at the overdose of 5×10^(15)cm^(-2)due to the partial amorphization in the surface region.Upon raising irradiation dose,a yellow emission in the as-grown sample is gradually quenched,probably due to the irradiation-induced generation of non-radiative recombination centers.展开更多
基金the National Natural Science Foundation of China(No.61904175)Jiangsu Provincial Key Research and Development Program(No.BE2020033)。
文摘Ion implantation induced damage in GaSb and its removal by rapid thermal annealing(RTA)have been investigated by Raman spectroscopy.The evolution of the Raman modes as a function of implantation fluence,annealing temperature and time has been analyzed.Results indicate that a lattice quality that is close to as-grown GaSb has been obtained by annealing the implanted samples at 500℃for 45 s.However,consequent surface analyses by scanning electron microscope(SEM)and atomic force microscope(AFM)show that a heavily perturbed layer contains voids due to the outdifiusion of Sb atoms on the surface remains.Mechanism of the damage recovery and the structure of the implanted layer are discussed based on the experimental results.
基金supported by the National Natural Science Foundation of China(Nos.12141502 and 12005017).
文摘Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for reducing the detection limit of high-purity germanium detectors and scintillator calorimeters,which are widely applied in dark matter and 0υββdetection experiments.The traditional adhesive bonding method between PTFE and copper is not conducive to working in liquid nitrogen and extremely low-temperature environments.To avoid adhesive bonding,PTFE must be processed for surface metallization owing to the mismatch between the PTFE and copper conductive layer.Low-background PTFE matrix composites(m-PTFE)were selected to improve the electrical and mechanical properties of PTFE by introducing SiO_(2)/TiO_(2) particles.The microstructures,surface elements,and electrical properties of PTFE and m-PTFE were characterized and analyzed following ion implantation.PTFE and m-PTFE surfaces were found to be broken,degraded,and cross-linked by ion implantation,resulting in C=C conjugated double bonds,increased surface energy,and increased surface roughness.Comparably,the surface roughness,bond strength,and conjugated double bonds of m-PTFE were significantly more intense than those of PTFE.Moreover,the interface bonding theory between PTFE and the metal copper foil was analyzed using the direct metallization principle.Therefore,the peel strength of the optimized electronic substrates was higher than that of the industrial standard at extremely low temperatures,while maintaining excellent electrical properties.
基金Project supported by the National Natural Science Foundation of China(Grant No.12075194)Sichuan Science and Technology Program(Grant No.2020ZYD055)。
文摘A nano-twinned microstructure was found in amorphous SiC after high-temperature annealing.Grazing incidence x-ray diffraction,high-resolution transmission electron microscopy,and electron diffraction were performed to characterize the microstructure and phase transition in the recrystallization layer.After 1500℃or 2-h annealing,3C-SiC grains and numerous stacking faults on the{111}planes were visible.Some 3C-SiC grains have nano-twinned structure with{011}planes.Between the nano-twinned 3C-SiC grains,there is a stacking fault,indicating that the formation mechanisms of the nano-twinned structure are related to the disorder of Si atoms.The increase in the twin thickness with increasing annealing temperature demonstrates that the nano-twinned structure can sink for lattice defects,in order to improve the radiation tolerance of SiC.
文摘Structural and morphological changes as well as corrosion behavior of N+implanted Al in 0.6 M NaCl solution as function of N+fluence are investigated.The x-ray diffraction results confirmed AlN formation.The atomic force microscope(AFM)images showed larger grains on the surface of Al with increasing N+fluence.This can be due to the increased number of impacts of N+with Al atoms and energy conversion to heat,which increases the diffusion rate of the incident ions in the target.Hence,the number of the grain boundaries is reduced,resulting in corrosion resistance enhancement.Electrochemical impedance spectroscopy(EIS)and polarization results showed the increase of corrosion resistance of Al with increasing N+fluence.EIS data was used to simulate equivalent electric circuits(EC)for the samples.Strong dependence of the surface morphology on the EC elements was observed.The scanning electron microscope(SEM)analysis of the samples after corrosion test also showed that the surfaces of the implanted Al samples remain more intact relative to the untreated Al sample,consistent with the EIS and polarization results.
基金National Magnetic Confinement Fusion Energy Research Project,Ministry of Science and Technology of China(Grant No.2015GB109002)the Innovation Fund of Postgraduate,Xihua University,China(Grant No.ycjj2018017)the National Natural Science Foundation of China(Grant No.21401173).
文摘The retention and release of deuterium in W–2%Y2O3 composite materials and commercially pure tungsten after they have been implanted by deuterium plasma(flux ~ 3.71 × 1021 D/m2·s, energy ~ 25 eV, and fluence up to 1.3 × 1026D/m2)are studied. The results show that the total amount of deuterium released from W–2%Y2O3 is 5.23 × 1020 D/m2(2.5 K/min),about 2.5 times higher than that from the pure tungsten. Thermal desorption spectra(TDS) at different heating rates(2.5 K/min–20 K/min) reveal that both W and W–2%Y2O3 have two main deuterium trapped sites. For the low temperature trap, the deuterium desorption activation energy is 0.85 eV(grain boundary) in W, while for high temperature trap, the desorption activation energy is 1.57 eV(vacancy) in W and 1.73 eV(vacancy) in W–2%Y2O3.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA02040100)the National Natural Science Foundation of China(Grant No.11975304)the Shanghai Municipal Science and Technology Commission(19ZR1418100)。
文摘The enhanced diffusion in materials under irradiation plays an important role in the long-term microstructural evolution. In this work, the self-ion irradiation in nickel was used as a model system to study the effect of radiation-enhanced diffusion on the implanted ion profiles. Initially, the depth profiles of vacancies and implanted ions for nickel self-ion irradiation with ion energies up to 15 MeV were computed by the high-efficiency Monte Carlo code IM3D(Irradiation of Materials in 3 D). The results are in good agreement with those predicted by SRIM(Stopping and Range of Ions in Matter).Then, diffusion coefficients as functions of temperature and damage rate were obtained, and the depth-dependent diffusion coefficients at various temperatures and damage rates were also illustrated. For this purpose, we used a temperature-dependent effective sink concentration for nickel, which was estimated from the available experimental investigations on the damage structures of irradiated nickel. At length, case studies on the time evolution of implanted ion profiles under the condition of nickel selfirradiation were performed and discussed based on Fick’s second law. The results help to understand the fundamental diffusion properties in ion irradiation, especially under higher-dose irradiation.
基金supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute(KHIDI)funded by the Ministry of Health&Welfare,Republic of Korea(Grant No:HI18C0493)
文摘Biodegradable stents made of magnesium(Mg)and its alloys have been developed to minimize persistent inflammation or in-stent restenosis,which are the main problems for permanent stents.However,their rapid corrosion behavior under physiological conditions leads to poor vascular compatibility and premature structural failure,which remains an important unsolved clinical problem.Herein,we demonstrate a new strategy for solving this problem by combining poly(ether imide)(PEI)coating and subsequent tantalum(Ta)ion implantation.The PEI coating covers the whole surface of the Mg stent uniformly via a spray coating technique and provides Mg with superior corrosion resistance and stable sirolimus-carrying ability.Ta ion implantation is conducted by a sputtering-based plasma immersion ion implantation technique only onto the luminal surface of the PEI-coated Mg stent.Its extremely short processing time(<30 s)permits preservation of the PEI coating’s corrosion protection ability and sirolimus loading characteristics.In addition,a Ta-implanted skin layer that forms on the topmost surface of the PEI coating plays an effective role in not only preventing a rapid release of sirolimus from the surface but also improving the PEI coating’s surface hydrophilicity.Based on in vitro cellular response and blood compatibility tests,Ta ion implantation leads to the improvement of endothelial cell adhesion/proliferation and suppression of platelet adhesion/activation regardless of sirolimus loading.These results indicate that the combination of PEI coating and Ta ion implantation has significant innovative potential to provide excellent vascular compatibility and prevent in-stent restenosis and thrombosis.
基金the Ministry of Science and Innovacion&Navarra Government for FUNCOAT projectthe Ministry of Economy and Competitiveness for MoM for LIFE(MAT2011-29698-C03-02)and for providing financial support to these projects.
文摘Problems in metal-on-metal (MoM) hip replacement systems still persist due to high wear rates, low corrosion resistance and release of toxic ions and nanoparticles. As a consequence of these effects, failure, infections, loosening or bone resorption is the typical problems in the hip prosthesis. In order to reduce failure due to corrosion and/or releasing ions and particles, this study presents some works in a novel nanoscale surface modification of cobalt-chromium alloy (CoCr) for obtaining improved surface conditions in these alloys for these applications. Improving corrosion resistant of these alloys and achieving a low wear rate are possible to reduce the total released ions and particles released from the surface of this material. According to it, three different treatments using oxygen at temperatures of 300°C, 350°C and 400°C were carried out by plasma immersion ion implantation technique (PI3). X-ray diffraction (XRD) analysis shows an increase in the formation of chromium oxides in the outer surface of the CoCr alloy. It allows improving in corrosion resistant in CoCr alloys. Moreover, total quantity of released Co, Cr and Mo ions have been reduced. Wear rate studies showed a very similar behaviour after the treatments in relation to untreated CoCr alloy and release rate from the treated surface of CoCr alloys was reduced in comparison with untreated CoCr alloy.
基金supported by the National Natural Science Foundation of China(Grant Nos.12025503,U1867215,and U1932134)Hubei Provincial Natural Science Foundation(Grant No.2019CFA036)+1 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.2042020kf0211)China Postdoctoral Science Foundation(Grant No.2020M682429)。
文摘Introducing heteroatoms and defects is a significant strategy to improve oxygen evolution reaction(OER)performance of electrocatalysts.However,the synergistic interaction of the heteroatom and defect still needs further investigations.Herein,we demonstrated an oxygen vacancy-rich vanadium-doped Co_(3)O_(4)(V-Ov-Co_(3)O_(4)),fabricated by V-ion implantation,could be used for high-efficient OER catalysis.X-ray photoelectron spectra(XPS)and density functional theory(DFT)calculations show that the charge density of Co atom increased,and the reaction barrier of reaction pathway from O∗to HOO∗decreased.V-Ov-Co_(3)O_(4) catalyst shows a low overpotential of 329 mV to maintain current density of 10 mA·cm^(−2),and a small Tafel slope of 74.5 mV·dec^(−1).This modification provides us with valuable perception for future design of heteroatom-doped and defect-based electrocatalysts.
基金Project supported by the National Natural Science Foundation of China(Grant No.12075194)the Fund of Collage Student Innovation and Entrepreneurship Training Program(Grant No.S202010619053)。
文摘Chemical disorder on the surface and lattice strain in GaN implanted by Fe^(10+)ions are investigated.In this study,3-MeV Fe^(10+)ions fluence ranges from 1×10^(13)ions/cm^(2)to 5×10^(15)ions/cm^(2)at room temperature.X-ray photoelectron spectroscopy,high-resolution x-ray diffraction,and high-resolution transmission electron microscopy were used to characterize lattice disorder.The transition of Ga-N bonds to oxynitride bonding is caused by ion sputtering.The change of tensile strain out-of-plane with fluence was measured.Lattice disorder due to the formation of stacking faults prefers to occur on the basal plane.
基金This work was supported by the Military Quality Engineering of China(No.1807WR0002).
文摘In this paper,the ESD discharge capability of GGNMOS(gate grounded NMOS)device in the radiation-hardened 0.18μm bulk silicon CMOS process(Rad-Hard by Process:RHBP)is optimized by layout and ion implantation design.The effects of gate length,DCGS and ESD ion implantation of GGNMOS on discharge current density and lattice temperature are studied by TCAD and device simulation.The size of DCGS,multi finger number and single finger width of ESD verification structures are designed,and the discharge capacity and efficiency of GGNMOS devices in ESD are characterized by TLP test technology.Finally,the optimized GGNMOS is verified on the DSP circuit,and its ESD performance is over 3500 V in HBM mode.
基金supported by the National Natural Science Foundation of China (No. 51575389, 51761135106)the National Key Research and Development Program of China (2016YFB1102203)+1 种基金the State Key Laboratory of Precision Measurement Technology and Instruments (Plit1705)the “111 Project” by the State Administration of Foreign Experts Affairs and the Ministry of China (Grant No. B07014)。
文摘To investigate the effect of dislocation structures on the initial formation stage of helium bubbles, molecular dynamics(MD) simulations were used in this study. The retention rate and distribution of helium ions with 2 ke V energy implanted into silicon with dislocation structures were studied via MD simulation. Results show that the dislocation structures and their positions in the sample affect the helium ion retention rate. The analysis on the three-dimensional distribution of helium ions show that the implanted helium ions tend to accumulate near the dislocation structures. Raman spectroscopy results show that the silicon substrate surface after helium ion implantation displayed tensile stress as indicated by the blue shift of Raman peaks.
文摘The n-type PbTe doped with 0.05 mol fraction Pbl2 was hot-pressed, and the sintered samples were implanted by Sn+ ions at 200 KeV with doses of 6×1016 and 1×1017 ions/cm2. The effect of Sn+ implantation on thermoelectric properties was then investigated. The results show that Sn+ ion implantation can modify thermoelectric properties of the n-type PbTe and greatly improve the dimensionless
基金Project supported by the National Key R&D Program of China(Grant No.2017YFE0131300)the National Natural Science Foundation of China(Grant Nos.61874128,61851406,and 11705262)+3 种基金Frontier Science Key Program of Chinese Academy of Sciences(Grant Nos.QYZDY-SSW-JSC032 and ZDBS-LYJSC009)Chinese–Austrian Cooperative R&D Project(Grant No.GJHZ201950),Program of Shanghai Academic Research Leader(Grant No.19XD1404600)K.C.Wong Education Foundation(Grant No.GJTD-2019-11)NCBiR within the Polish–China(Grant No.WPC/130/NIR-Si/2018).
文摘The defect evolution in InP with the 75 keV H^(+)and 115 keV He^(+)implantation at room temperature after subsequent annealing has been investigated in detail.With the same ion implantation fluence,the He^(+)implantation caused much broader damage distribution accompanied by much higher out-of-plane strain with respect to the H^(+)implanted InP.After annealing,the H^(+)implanted InP did not show any blistering or exfoliation on the surface even at the high fluence and the H2 molecules were stored in the heterogeneously oriented platelet defects.However,the He molecules were stored into the large bubbles which relaxed toward the free surface,creating blisters at the high fluence.
基金Project supported by the National Natural Science Foundation of China(Grant No.12105037)the Key Project of National Natural Science Foundation of China-China Academy of Engineering Physics Joint Foundation(Grant No.U1830204)。
文摘Oxygen ions(O;)were implanted into fused silica at a fixed fluence of 1×10^(17) ions/cm^(2) with different ion energies ranging from 10 ke V to 60 ke V.The surface roughness,optical properties,mechanical properties and laser damage performance of fused silica were investigated to understand the effect of oxygen ion implantation on laser damage resistance of fused silica.The ion implantation accompanied with sputtering effect can passivate the sub-/surface defects to reduce the surface roughness and improve the surface quality slightly.The implanted oxygen ions can combine with the structural defects(ODCs and E′centers)to reduce the defect densities and compensate the loss of oxygen in fused silica surface under laser irradiation.Furthermore,oxygen ion implantation can reduce the Si-O-Si bond angle and densify the surface structure,thus introducing compressive stress in the surface to strengthen the surface of fused silica.Therefore,the laser induced damage threshold of fused silica increases and the damage growth coefficient decreases when ion energy up to30 ke V.However,at higher ion energy,the sputtering effect is weakened and implantation becomes dominant,which leads to the surface roughness increase slightly.In addition,excessive energy aggravates the breaking of Si-O bonds.At the same time,the density of structural defects increases and the compressive stress decreases.These will degrade the laser laser-damage resistance of fused silica.The results indicate that oxygen ion implantation with appropriate ion energy is helpful to improve the damage resistance capability of fused silica components.
基金the National Natural Science Foundation of China(Grant No.11875211)the Major Science and Technology Program of Changsha,China(Grant No.kq1902046)the Fundamental Research Funds for the Central Universities,China.
文摘Despite anionic doping has been widely implemented to increase the visible light activity of TiO_(2),it often gives rise to a dramatical anodic shift in current onset potential.Herein,we show an effective method to achieve the huge cathodic shift of TiO_(2) photoanode with significantly enhanced visible light photo-electrochemical activity by nitrogen/cobalt coimplantation.The nitrogen/cobalt co-doped TiO_(2)nanorod arrays(N/Co-TiO_(2))exhibit a cathodic shift of 350 mV in onset potential relative to only nitrogen-doped TiO_(2)(N-TiO_(2)).Moreover,the visible-light(λ>420 nm)photocurrent density of N/Co-TiO_(2) reaches 0.46 mA/cm^(2),far exceeding 0.07 mA/cm^(2) in N-TiO_(2)at 1.23 V versus reversible hydrogen electrode(RHE).Systematic characterization studies demonstrate that the enhanced photo-electrochemical performance can be attributed to the surface synergic sputtering of high-energy nitrogen/cobalt ions.
基金by the Hunan Provincial Key Research and Development Plan(No.2017GK2040)the Natural Science Foundation of Hunan Province of China(No.2019JJ50617)the General Project of Hunan Provincial Education Department(No.19C1773)。
文摘The bifacial n-PERT(Passivated Emitter Rear Totally diffused)solar cells were fabricated using a simplified process in which the activation of ion-implanted phosphorus and boron diffusion were performed simultaneously in a high-temperature process.For further efficiency improvement,the rear side doping level was regulated by applying two different implantation doses and the chemical etching step of boron rich layer(BRL)was added,and their effects on cell performance were investigated.The solar cells average efficiency reaches 20.35%with a bifaciality factor of 90%by optimizing rear side doping level,which can be explained by the decrease of Auger recombination.And it is further enhanced to 20.74%by removing the front side BRL due to the improvement of surface passivation and bulk lifetime.The improved fabrication process possesses the advantages of low complexity and cost and high cell efficiency and bifaciality factor which could provide a promising way to the commercial production of bifacial n-PERT solar cells.
文摘The composition and structure of Ti 6Al 4V alloy plasma based ion implanted with nitrogen was investigated.The nitrogen depth distribution shows more antiballistic with distribution peak heightened with increased implantation time(dose),and more like a parabola at the low implantation pulse voltage.When implantation pulse voltage is increased,the implantation depth increased with the nitrogen distribution peak being deepened,widened and lowered somewhat.TiN,TiN+Ti 2N,or Ti 2N second phases were formed in the implanted layer.The relative percentage of nitrogen content in the form of TiN increases when going deeper into the implanted(TiN formed) layer.The increase of implantation pulse width and/or time is favourable for the formation of TiN rather than Ti 2N.It is unfavourable for formation of any nitrides when implantation pulse voltage is decreased to 30kV or less.Tiny crystalline particles (made mainly of Ti 2N and a smaller percentage of TiO 2 phases) of regular shapes such as triangle and tetragon, etc .(about 20 nm) are found distrbuted dispersively in the near surface region of samples implanted at the high implantation pulse voltage (75kV).
基金supported by National Key R&D Program of China (No. 2018YFB1500500).
文摘Thermal annealing and laser irradiation were used to study the activation rate of phosphorus in silicon after ion implantation.The activation rate refers to the ratio of activated impurity number to the total impurity number in the sample.After injecting phosphorus with the dose and energy(energy=55 keV,dose=3×10^(15) cm^(-2)),the samples were annealed at different temperatures,and laser irradiation experiments were performed after annealing.The experimental results showed that the activation rate of phosphorus was the highest at 850℃,and the highest activation rate was 67%.Upon femtosecond laser irradiation samples after thermal annealing,while keeping the crystalline silicon surface without damage,the activation rate was improved.When the energy-flux density of the femtosecond laser was 0.65 kJ/cm2,the activation rate was the highest,increasing from 67%to 74.81%.
基金the Key-Area Research and Development Program of Guangdong Province,China(Grant Nos.2019B010132001,2020B010174003,and 2019B121204004)the Basic and Application Basic Research Foundation of Guangdong Province,China(Grant Nos.2020A1515110891 and 2019A1515111053)the Fund from the Ion Beam Center(IBC)at HZDR.
文摘We show the structural and optical properties of non-polar a-plane GaN epitaxial films modified by Si ion implantation.Upon gradually raising Si fluences from 5×10^(13)cm^(-2)to 5×10^(15)cm^(-2),the n-type dopant concentration gradually increases from 4.6×10^(18)cm^(-2)to 4.5×10^(20)cm^(-2),while the generated vacancy density accordingly raises from 3.7×10^(13)cm^(-2)to 3.8×10^(15)cm^(-2).Moreover,despite that the implantation enhances structural disorder,the epitaxial structure of the implanted region is still well preserved which is confirmed by Rutherford backscattering channeling spectrometry measurements.The monotonical uniaxial lattice expansion along the a direction(out-of-plane direction)is observed as a function of fluences till 1×10^(15)cm^(-2),which ceases at the overdose of 5×10^(15)cm^(-2)due to the partial amorphization in the surface region.Upon raising irradiation dose,a yellow emission in the as-grown sample is gradually quenched,probably due to the irradiation-induced generation of non-radiative recombination centers.