Increasing Implantation Dose Research Articles

Mechanical response of carbon ion implanted ferrite via atomic simulations

Ion implantation plays a nontrivial role in improving the mechanical properties of materials. Unfortunately, the atomic-scale understanding and awareness of the improvement mechanisms remain insufficiently clear and accurate. This paper investigates the nanostructural evolution of carbon ion implanted ferrite and the mechanical response under uniaxial tension leveraging molecular dynamics (MD) simulation, providing direct atomic-scale evidence of alloy strengthening. Regarding nanostructural evolution, grain boundary migration induced by carbon ion implantation becomes significant with increasing doses. However, point defects and amorphous structures caused by collision cascades tend to saturate gradually with increasing implantation doses. Uniaxial tensile test results indicate that the strength of all ion-implanted samples is appreciably enhanced compared to non-implanted samples, especially with an implantation dose of 6.23 × 1013 ions/cm2, where the strength increases by 39%. The underlying strengthening mechanism is that defects, amorphous structures, and lattice distortions induced by ion implantation collectively act as formidable barriers to dislocation motion during plastic deformation, strongly governing dislocation propagation and multiplication. More importantly, the interaction between carbon atoms from ion implantation and dislocations renders the formation of Cottrell atmospheres, which further enhances solid solution strengthening by pinning dislocations. These results advancing the fundamental understanding of nanostructural evolution and strengthening mechanism under ion implantation suggest a mechanistic strategy for augmenting alloy strength.

Formation of cesium carbonate in ion-implanted graphite, examined with dual-source x-ray photoelectron spectroscopy, density functional theory calculations and thermodynamic modelling

A sample of highly orientated pyrolytic graphite (HOPG) was implanted with Cs+ ions in order to study the effect on the graphite matrix and the chemical form of Cs once embedded. The mean implantation depth was calculated to be ∼22 nm, allowing for investigation with X-ray Photoelectron Spectroscopy, (XPS), where both a traditional Al Kα X-ray source and a higher energy Ag Lα source was used for an increased sampling depth deeper into the surface. Analysis found that there was a reduction of sp2 C–C bonding with increasing implantation dose, resulting in a total loss of sp2 character at ∼6 atomic % Cs+. A striking increase in higher binding energy components (285.8–289.4 eV) in the C 1s spectra cannot be attributed solely to the presence of C–O species, instead indicating a dramatic re-ordering of the graphitic lattice to accommodate and neutralize the embedded Cs. XPS analysis indicates the formation of cesium carbonate within the graphitic material; this is reinforced by analysis of a Cs2CO3 reference sample. Additionally, thermodynamics equilibrium simulations, supported by simplified density functional theory (DFT) calculations, are performed, leading to strong agreement with the XPS findings; that is, the most stable form of Cs within the graphite matrix is expected to be cesium carbonate (Cs2CO3), which is in thermodynamic equilibrium with degraphitised HOPG and oxygenated degraphitised HOPG.

Exploration of vacancy defect formation and evolution in low-energy ion implanted pure titanium

Hydrogen behavior and its related property degradation have been long-standing problems for structural materials used in hydrogen energy. The hydrogen atoms can easily interact with vacancy defects, forming hydrogen vacancy complexes which play an important role in the hydrogen-induced structural damage. However, the interaction mechanisms and its evolutions are still unclear. In this work, the hydrogen behavior and the interaction between hydrogen with defects in pure titanium implanted by 30 keV and 50 keV hydrogen ions were studied by positron annihilation spectroscopy. The implantation doses were 5 × 1016 H/cm2, 1 × 1017 H/cm2 and 5 × 1017 H/cm2, respectively. The results show that the structural damage of pure titanium is positively correlated with the ion implantation energy. For the implantation of 50 keV hydrogen ions, a large number of hydrogen atoms are deposited in the samples. With the increase of implantation dose, the formation of hydrogen vacancy complexes (HmVn) reduces the effective open-volume of defects and changes the structural features of defects in implanted samples, thus suppressing the formation of vacancy defects and causing the damage range shifting from the peak damage (PD) region to the near surface (NS) region. Eventually, the movement of hydrogen atoms intensifies, and the “hydrogen peak” becomes more obvious. The chemical information related to deposited hydrogen atoms can be easily identified in the processing and analysis of positron annihilation results.

Effect of Low-Energy Nitrogen Ion Implantation on Friction and Wear Properties of Ion-Plated TiC Coating

To further improve the performance of the coated tools, we investigated the effects of low-energy nitrogen ion implantation on surface structure and wear resistance for TiC coatings deposited by ion plating. In this experiment, an implantation energy of 40 keV and a dose of 2 × 1017 to 1 × 1018 (ions/cm2) were used to implant N ions into the TiC coatings. The results indicate that the surface roughness of the coating increases first and then decreases with the increase of ion implantation dose. After ion implantation, the surface of the coating will soften and reduce the hardness, and the production of TiN phase will gradually increase the hardness. Nitrogen ion implantation can reduce the friction coefficient of the TiC coating and improve the friction performance. In terms of wear resistance, the coating with an implant dose of 1×1018 ions/cm2 has the greatest improvement in wear resistance. Tribological analysis shows that the improvement in the performance of TiC coatings implanted with N ions is mainly due to the effect of the lubricating implanted layer. The implanted layer mainly exists in the form of amorphous TiC, TiN phase, and sp2C–C phase.

Initial activation behavior of boron at low temperatures with implantation doses below the amorphization threshold

The initial behavior of boron activation at low temperatures was experimentally studied at implantation doses below the threshold for amorphization of the silicon substrates. A test structure was developed to analyze the activation in the early stage of annealing at temperatures below 400 °C. Saturation of the activation level following the decay of the activation rate was observed during annealing for long times at temperatures between 350 °C and 400 °C. Boron activation was enhanced due to the channeling effect of the implanted boron ions when the implantation tilt angle was reduced from 7° to 0°. However, the active boron percentage declined with increasing implantation dose. Boron activation was degraded by silicon implantation at low doses following the boron implantation. The low activation energies extracted from the experimental data indicated that boron activation was limited by the metastable defect complexes under subamorphizing implantation.

Wetting and interfacial behavior of Cu–Al/SiC systems: Influences of Si ion implantation and Al concentration

Three doses (5 × 1015, 1 × 1016 and 5 × 1016 ions/cm2) of Si ions implantation into Si-terminated 6H–SiC substrate were carried out at an energy of 20 keV at room temperature. The wetting of pristine and Si-implanted 6H–SiC (Si–SiC) substrates by molten pure Cu, Cu-(42.9, 48.7, 70.4)Al alloys and pure Al were performed by the sessile drop technique under vacuum of ∼4 × 10−4 Pa at 1373 K. The surface characteristics of SiC substrates and wetting and interfacial behavior of Cu–Al/(Si-)SiC systems were analyzed and discussed. The equilibrium or final contact angles (θ) of Cu–Al/Si–SiC systems were increased more or less with the increase of Si ion implantation dose, and the Si ion implantation can markedly enhance the wettability of Cu-(0, 42.9)Al/SiC systems but weaken that of Cu-(48.7, 70.4, 100)Al/SiC systems. Interestingly, the graphitization phenomenon disappeared at the drop/substrate interface when the Al concentration was over 42.9%, and the Cu-42.9Al alloy cannot wet both the pristine 6H–SiC and Si–SiC substrates. These phenomena further demonstrated that the wetting of metal/SiC systems can be mainly determined by the metal-substrate interactions derived from the metal composition under a vacuum of and surface characteristics of metal drop and ceramic substrate during wetting.

Радиационно-стимулированная трансформация спектров отражения пленок диазохинон-новолачного фоторезиста при имплантации ионов сурьмы

A method of measuring the reflection spectra was used to study the implantation of photoresist films of the photoluminescence FP9120 with a thickness of 1.8 μm, implanted by antimony ions, deposited by centrifugation on the surface of p-type silicon plates (ρ = 10 Ω cm) with the (111) orientation. It was shown that, implantation leads to the decrease of photoresist refractive index caused by the radiation linkage of novolac resin, as well as the decrease of molecular refraction and photoresist density. In the opacity area of photoresist film reflectance coefficient growth was observed at the increase of implantation dose.

Improving the performance properties of titanium alloy VT6 after ion implantation with copper and aluminum ions

The objective of this work was to study the processes occurring on the surface of VT6 titanium alloy samples when implanting with copper and aluminum ions. Elemental composition, structural-phase state, mechanical and tribological properties of VT6 titanium alloy surface layers modified by aluminum and copper ions was being researched. As can be seen from the undertaken studies, the mode of high-intensity ion-implantation process makes it possible to obtain ion doped surface layers of VT6 alloy containing finely dispersed intermetallic phases and a solid solution of aluminum and copper in titanium of a composition varying in depth. The thickness of the ion-doped layer, the average grain size of the intermetallic phases and their conglomerates increases with the increase in implantation dose while aluminum implantation is in progress. It has been shown that the implantation of aluminum and copper ions into VT6 alloy leads to a considerable increase in its microhardness and wearability. Based on the research results, a conclusion on the positive effect of a structural-phase state of ion-doped titanium layers on their mechanical and tribological properties of VT6 titanium alloy has been drawn.

Correlation between crystal structure and mechanical performance of Cr-implanted 300M high-strength steel using X-ray diffraction method

In order to study the influence of crystal structure change due to implantation dose on the hardness and wear performance of 300M high-strength steel, samples were surface modified by Cr implantation with dosages of 5.0 × 1016, 1.5 × 1017 and 3.0 × 1017 ions/cm2. X-ray diffraction method, which was already applied in studies on the microstructure of deformed and heat-treated materials, was used to study the crystal structure of the implanted steel, and the results were corrected with the hardness and wear performance. The solid solution strengthening effect and microstructure vary with increase in implantation dose. Owing to strong solid solution hardening of Cr, small average crystallite size and high dislocation density, the hardness and wear resistance of implanted steel with dose of 5.0 × 1016 ions/cm2 were found to be the highest compared with other samples. Moreover, although the crystallite size of the implanted sample with dose of 3 × 1017 ions/cm2 was similar to that of substrate and the dislocation density was lower than that of the substrate, its higher hardness and lower specific wear rate were due to the solid solution hardening and perhaps Cr clusters reinforcement.

VT6 TITANIUM ALLOY WEARABILITY INCREASE VIA IMPLANTATION OF COPPER AND ALUMINUM IONS

The relevance of the article is due to the fact that the use of titanium alloys within friction joints is restrained by their low resistance to wear while traditional methods of increasing their wear resistance are ineffective. The objective of this work was to study the processes occurring on the surface of VT6 titanium alloy samples when implanting with copper and aluminum ions, as well as in friction. Elemental composition, structural-phase state, mechanical and tribological properties of VT6 titanium alloy surface layers modified by aluminum and copper ions during the high-intensity ion-implantation process was being researched. As can be seen from the undertaken studies, the mode of the high-intensity ion-implantation process makes it possible to obtain ion doped surface layers of VT6 alloy containing TiAl, Ti3Al, Ti3Cu, Ti2Cu, TiCu finely dispersed intermetallic phases and a solid solution of aluminum and copper in titanium of composition varying in depth. The thickness of the ion-doped layer, the average grain size of the intermetallic phases (from 18 to 55nm) and their conglomerates (from 45 to 280 nm) increases with the increase in implantation dose from 2⋅1017 to 1.2⋅1019 ion/cm2 while aluminum implantation (from 0.42 to 2.1 μm) is in progress. It has been shown that the implantation of aluminum and copper ions into VT6 alloy leads to a considerable increase in its microhardness and wearability. Based on the research results, a conclusion on the positive effect of a structural-phase state of ion-doped titanium layers on their mechanical and tribological properties of VT6 titanium alloy has been drawn.

The effect of N+ ion-implantation on the corrosion resistance of HiPIMS-TiN coatings sealed by ALD-layers

Plasma immersion ion implantation (PIII) was studied as a pretreatment method for improving the surface activity of TiN coatings deposited by high power impulse magnetron sputtering (HiPIMS) before being sealed with an ALD (Atomic layer deposition)-Al2O3 hybrid coating. The effect of different implantation energy and dose of nitrogen plasma on the microstructure and surface morphology of TiN coatings were investigated, and the surface morphology and fracture cross-section images of TiN/Al2O3 hybrid coatings with and without PIII pretreatment were compared. The corrosion protection properties were explored with linear sweep voltammetry in 3.5% NaCl solution at the room temperature. The results indicated that the N+ pre-ion-implantation had a significant influence on the microstructure and surface morphology of TiN coatings. With the increase of ion implantation energy and dose, TiN coatings gradually alter from the preferred orientation (200) to a mixture of (200) and (111), accompanied by the decrease of grain size on the surface. Moreover, the PIII pretreatment of the TiN coatings could significantly shorten the incubation time of the nucleation of ALD films, leading to a denser but thinner (at the same deposition cycles) layer of Al2O3, which plays a positive role in corrosion resistance. The coverage of ALD-Al2O3 films was improved with the increase of the nitrogen ion implantation energy and dose, resulting in better corrosion protection.

Reflection Spectra Modification of Diazoquinone-Novolak Photoresist Implanted with B and P Ions

We investigate FP9120 positive photoresist films 1.8 μm thick that are spin-coated on the surface of KDB-10 (111) silicon wafers and implanted with В+ and Р+ ions by measuring the reflection’s spectra. It is shown that implantation reduces the refractive index of the photoresist. In the opacity region of the photoresist film, the reflection coefficient grows with an increasing implantation dose, especially in the case of P+ ion implantation. The spectral dependences of the optical length for the implanted photoresist films have two regions with anomalous dispersion near the wavelengths of 350 and 430 nm, which correspond to the absorption bands of naphthoquinone diazide molecules.

Comparative study of nitrogen implantation effect on mechanical and tribological properties of Ti-6Al-4V and Ti-10Zr-10Nb-5Ta alloys

The effect of nitrogen implantation on mechanical and tribological properties of Ti-6Al-4V and Ti-10Zr-10Nb-5Ta alloys was studied. Increasing implantation dose from 1 × 1016N+/cm2to 2 × 1017N+/cm2leads to increase gradually both hardness and Young's modulus. The results show that implantation of 2 × 1017N+/cm2allowed to double the value of Young's modulus and to triple the value of hardness. Friction tests that have been conducted against 100Cr6 steel and alumina balls showed that tribological behavior of the two alloys depend on the nature of the counterpart material and is strongly affected by the implanted dose of nitrogen.

Исследование приповерхностного слоя германия, имплантированного ионами кобальта

The results of investigation of germanium surface nanostructured by ion implantation are presented. Single-crystal plates of germanium (c Ge) were irradiated by cobalt ions with an energy of 40 keV in the dose range (2 × 1016 - 8 × 1016) Co + / cm2. The method of scanning electron microscopy (SEM) has been used to study the evolution of the morphology of germanium surface with an increase of implantation dose. It has been found that with increasing dose of implantation, a layer of spherical formations with diameter of ~ 150 nm gradually forms on the surface of implanted germanium. The analysis of X-ray diffraction spectra indicated the appearance of nano-sized cobalt germanide (CoGe) particles in the implanted layer.

Low energy B+ implantation induced optical and structural characteristics of aliphatic and aromatic polymers

Influence of 50 keV boron ion implantation on the optical and structural properties of aliphatic PMMA and aromatic PET polymers has been studied. Samples were implanted with various fluences ranging from 1 × 1015 to 5 × 1016 B+ cm−2 at normal incidences. The intensity of most of the fundamental bands of these polymers, appearing in Raman and FTIR spectra, decreases significantly pointing towards structural rearrangement as an effect of low energy B+ implantation. UV–visible spectroscopy reveals significant increase in the value of disorder content (Urbach energy) and refractive index with increasing implantation dose for both the polymers. The decline in optical energy gap is found to be 22.3% for PMMA and 11.3% for PET due to B+ implantation. The degree of structural and optical modifications is more in PMMA in comparison to PET besides having same electronic to nuclear energy loss ratio. Both the chain scissioning and cross-linking mechanisms play significant role in the modification of the structure and properties of PMMA while chain scissioning is dominant in PET for the same. Such ion beam induced alteration in optical and structural properties makes these polymers ideal for making optical sensors, sun glasses, UV blocking devices and intraocular lenses etc.

Wetting and interfacial behavior of molten Al–Si alloys on SiC monocrystal substrates: effects of Cu or Zn addition and Pd ion implantation

C-terminated 6H-SiC (0001) single crystal substrates implanted with Pd ions with an energy of 20 keV and three fluences of 5 × 1015, 5 × 1016 and 5 × 1017 ions/cm2 at room temperature. The wetting experiments of SiC by molten Al–10Si, Al–10Si–4Cu and Al–10Si–10Zn were performed by using the sessile drop method in a high vacuum at 1323 K to determine the effects of the third element (Cu and Zn) addition and Pd ion implantation on the wettability of Al–10Si/SiC system. The experimental results showed that the wettability of Al–10Si/SiC system can be improved significantly by adding the 4% Cu with the final contact angle decreasing from ~ 60° to ~ 40°. The final contact angle of Al–10Si/SiC system decreased sharply from ~ 60° to ~ 26° after the addition of 10% Zn, which can be mainly derived from the evaporation behavior of Zn at the interface. The spreading time for reaching the equilibrium or slow spreading stage of the three Al–10Si(– 4Cu, – 10Zn)/SiC systems was prolonged more or less with the increase of Pd implantation dose, which can be mainly attributed to the variation of interfacial interactions between drops and Pd-implanted SiC substrates. Moreover, the final contact angles of Al–10Si/SiC and Al–10Si–4Cu/SiC systems decreased while that of Al–10Si–10Zn/SiC system almost kept constant with increasing the Pd implantation dose.

Nitrogen ion implantation effects on the structural, optical and electrical properties of CdSe thin film

In the present study, thin films of cadmium selenide (CdSe) are deposited on ITO substrate by electrodeposition method using aqueous solution of 3CdSO4·8H2O and SeO2. These films are implanted with 40 keV N+ ions with different fluencies i.e. 1 × 1015, 5 × 1015, 1 × 1016 and 5 × 1016 ions/cm2 using a beam current of 0.9 µA. The structural, morphological, optical and electrical properties of pristine and nitrogen ion-implanted CdSe thin films are analyzed using XRD, SEM, AFM, UV-PL Spectrophotometer and I–V four probes setup. XRD analysis revealed the effects of nitrogen ions on the structural parameters such as grain size, FWHM, micro strain and dislocation density etc. Crystallanity of the material increased with increase in implantation dose. SEM and AFM analysis show decrease in the surface roughness with implantation. From the optical studies, band gap value decreased from 2.50 to 2.29 eV with increase in N+ implantation doses. Noticeable changes in the electrical properties are also reported. The effect of N+ ion implantation on the properties of CdSe thin films are discussed on the basis of lattice disorder.

Effects of Fluorine on the NBTI Reliability and Low-Frequency Noise Characteristics of p-MOSFETs

The concurrent effect of fluorine implantation with various energy and dose on reliability and low-frequency noise characteristics of p-MOSFETs was investigated. The $\Delta $ VT degradation that represents device lifetime of p-MOSFETs with fluorine implantation under negative-bias temperature instability stress was less than that without fluorine implantation. The device lifetimes were improved as the fluorine implantation energy and dose increase. The power law exponent $n $ with the fluorine implantation was larger than that without fluorine implantation. This was related to boron diffusion within the gate oxide because the F atoms enhance the diffusivity of the boron. The difference of flicker noise levels between simulation and measurement data at 1 kHz was much greater than that at 10 Hz, which means that F atoms were mainly located near the Si/SiO2 interface rather than in the bulk oxide. The fluorine implantation reduced the ID-RTS noise amplitude, which was believed to contribute to the effective passivation of the dominant traps within the gate oxide. Also, the flicker noise was less dependent on implantation energy. But, flicker noise was reduced with increasing implantation dose. Therefore, fluorine implantation is potentially significant for reducing low-frequency noise as well as improving reliability characteristics.

Enhanced gettering of gold at end-of-range defects in high energy ion implanted silicon

We report on the gettering behavior of Au at end-of-range (EOR) defects in float-zone grown Si(111), implanted with 1.5 MeV Au 2+ ions at room temperature. The effects of implantation dose and annealing temperature on the thermal evolution of gettering behavior of EOR defects have been investigated using Rutherford backscattering spectrometry, while the microstructural evolution of Au implanted Si(111) has been studied using cross-sectional transmission electron microscopy combined with high resolution transmission electron microscopy. The gettering efficiency of EOR defects, comprising of dislocation loops, has been found to increase with increase in implantation dose up to 1.2 x 10 15 ions cm -2 , beyond which it was found to saturate at about 5 x 10 14 atoms cm -2 for annealing at 850 o C. We have observed that the gettering efficiency of the EOR defects for Au increased with increase in annealing temperature and reached 9 x 10 14 atoms cm -2 for annealing at 950 o C. The observed enhanced gettering efficiency of EOR defects is very promising for gettering applications in Si devices.

Modification of polyvinyl alcohol surface properties by ion implantation

We describe our investigations of the surface physicochemical properties of polyvinyl alcohol modified by silver, argon and carbon ion implantation to doses of 1×1014, 1×1015 and 1×1016ion/cm2 and energies of 20keV (for C and Ar) and 40keV (for Ag). Infrared spectroscopy (IRS) indicates that destructive processes accompanied by chemical bond (CO) generation are induced by implantation, and X-ray photoelectron spectroscopy (XPS) analysis indicates that the implanted silver is in a metallic Ag3d state without stable chemical bond formation with polymer chains. Ion implantation is found to affect the surface energy: the polar component increases while the dispersion part decreases with increasing implantation dose. Surface roughness is greater after ion implantation and the hydrophobicity increases with increasing dose, for all ion species. We find that ion implantation of Ag, Ar and C leads to a reduction in the polymer microhardness by a factor of five, while the surface electrical resistivity declines modestly.