Influence Of Ions Research Articles

Formation and depth distribution of optically active centers in diamond implanted with high energy xenon ions

The depth distributions of the spectral parameters of Raman and luminescence features of diamond implanted with Xe ions of an energy 167 MeV have been studied in as-irradiated state and after post-irradiation annealing. The Raman data show that the distribution of radiation defects in the as-irradiated layer follows the nuclear stopping power of the ions. It has been found that the two major mechanisms determining the distribution of intensity of the luminescence centers are the quenching due to crystal lattice damage and the instantaneous heating due to intense electronic stopping. It has been shown that the strong nuclear stopping at the end of the ion penetration produces a highly disordered buried layer. The atomic structure of this layer completely loses its crystallinity for ion fluences above 3 × 1014 cm−2. This atomic structure does not collapse into graphite during high temperature annealing and can be regarded as amorphous diamond. It has been shown that the post-irradiation annealing produces secondary radiation defects far deeper than the depth of the ion penetration. This deep defect production is explained by the dislocations propagating from the disordered layer into the diamond bulk during heating.

Influence of energetic heavy ion sputtering on lifetime of alloy target

When energetic heavy ions are incident on negatively charged structure that collects and deposits ions, ion sputtering will occur. Metal wire is a structure commonly used for accelerating ions, the incidence of continuous high-throughput ions can cause surface loss of metal wire, affecting the service performance and lifespan of the metal wire. The SRIM software commonly used for calculating sputtering yield cannot consider the multi-body interaction problem contained in the alloy crystal structure. so, there is a significant error in calculating the sputtering yield of high-energy ions incident on alloy target. Based on the molecular dynamics method and Langevin temperature control model, the calculation model of ion sputtering parameters of energetic metal ions incident on alloy target is established in this work. The model is used to calculate the sputtering yield under the conditions of intact surface lattice of the target material and long-term incident surface lattice damage. The damages to the cathode metal wire under different incident ion fluences are further calculated, and the cross-sectional characterization of the metal wire is carried under typical working condition. The results show that the discrepancy between the experimental value and the theoretical value is less than 10%, which verifies the accuracy and applicability of the theoretical model. Based on this model, the search direction for sputtering resistant materials is proposed, meanwhile, a theoretical optimization is carried out to improve the service life of metal wire, and a method of using Ni-Ti alloy to improve the service life of metal wires is proposed, which is of great significance for predicting the service life of the metal wire under different conditions.

Diamond-defect engineering of NV− centers using ion beam irradiation

The interplay between ion beam modification techniques in the MeV range and the controlled generation of negatively charged nitrogen-vacancy (NV−) centers in nitrogen-doped synthetic diamond crystals is explored. An experimental approach employing both light (H+) and heavy (Br+6) ions was followed to assess their respective impacts on the creation of NV− centers, using different ion energies or fluences to generate varying amounts of vacancies. Photoluminescence spectroscopy was applied to characterize NV− and neutral NV0 centers. Initially, no NV centers were detected post-irradiation, despite the presence of substitutional nitrogen and vacancies. However, after annealing at 800 °C (and in some cases at 900 °C), most samples exhibited a high density of NV0 and especially NV− centers. This demonstrates that thermal treatment is essential for vacancy‑nitrogen recombination and NV− formation, often through electron capture from nearby nitrogen atoms. Notably, we achieved high NV− densities without graphitization, which is essential for preserving the material's properties for quantum applications. This study underscores and quantifies the effectiveness of MeV-range ions in controlling vacancy distributions and highlights their potential for optimizing NV− center formation to enhance the sensitivity of diamond-based quantum magnetic sensors.

Ion Implantation of Copper Electrodes to Elucidate the Effect of Subsurface Oxygen and Surface Roughness for the Electrochemical CO2 Reduction Reaction

The electrochemical reduction of CO2 has the potential to be a viable method to consume anthropogenic CO2, while producing value added products such as CO and C2H4 in a carbon negative way. Copper is a unique electrocatalyst for the CO2 reduction reaction as it can produce products that require more than two electrons (such as C2H4 and C2H5OH) with reasonable selectivity. This has resulted in copper being an intensely studied catalyst over the past several decades in an attempt to understand why it is able to produce these unique products, but also to promote the production of the likes of C2H4 and C2H5OH with better selectivity, activity and stability. While excellent progress has been made, there is still plenty of debate around whether the enhanced performance of copper electrodes stems from surface roughness effects or subsurface oxygen.In the past, these two mechanisms have been difficult to decouple because of the fact that to synthesise an electrode with subsurface oxygen, surface roughness also tends to be induced. In this work, ion implantation of neon and oxygen was used to decouple these effects. The theory was that while the oxygen ion implantation will induce subsurface oxygen sites and surface roughness, the neon ion implantation will only induce surface roughness. Interestingly, it was found that both the oxygen and neon ion implantation resulted in decreased activity and selectivity for CO and C2+, with increasing ion fluence. These decreases in performance were in spite of an increase in the surface roughness of the electrode, which means that the ion implantation affected the inherent performance of the catalyst. This was in contrast to the sample that was annealed in air which had increased surface roughness, however, the normalised activity was consistent with that of the as-made catalyst. X-ray absorption spectroscopy and x-ray photoelectron spectroscopy were used to understand the loss in performance, which showed that the as the ion fluence increased, the Cu:CuO ratio and the relative O 1s Cu2O concentration on the electrode surface increased in an equivalent fashion for both the neon and oxygen implantation. Additionally, there was also a decrease in the number of oxygen vacancies, with increasing ion fluence. This shows that while the ion implantation increased the surfaced roughness of the electrode, it was able to reduce the surface Cu2+ to Cu1+ and Cu0, which resulted in the decreased performance of the electrode, suggesting that the subsurface oxygen is the key parameter that should be optimised, over the surface roughness of the electrode.

Studies on the retarded recrystallization of tungsten in CIMPLE-PSI exposed under very-high target temperature and long He+-fluence

Abstract Experiments are carried out in CIMPLE-PSI, to understand the recrystallization behavior of tungsten (W) exposed under very-high target temperature and ITER relevant long He+-fluence. The effect of helium bubbles on possible retardation of the recrystallization process is also studied. W samples were simultaneously exposed under He plasma and annealed by the plasma heat-load, in contrast to previously reported experiments in literature, which were carried out sequentially. Exposed samples are characterized by field emission scanning electron microscopy (FESEM), Vickers surface micro-hardness, nano-hardness and electron backscattered diffraction (EBSD). It is observed that the sample exposed to plasma under the highest temperature (1866 K) suffered acute retarded grain growth. This also contained small, unrecovered grains on the exposed surface. FESEM imaging of the cross-sections confirms that relatively smaller helium bubbles still form even at very high temperature conditions, which can impede the grain growth locally, whenever they are forming right on the grain boundaries. This results in an inhomogeneous mixture of surface grains with sizes ranging from a few micrometers to a few tens of micrometers. EBSD estimates that the plasma exposed surface was only 34% recrystallized. The second sample exposed at a lower temperature (1699 K) but for three times higher fluence (ion fluence: 1.19 × 1027 m−2) was almost fully recrystallized, which shows retardation diminishes very fast with the duration of the exposure. Hardness measurements were undertaken to understand the variation with plasma exposure/annealing temperature and the extent of recrystallization, with three different probing length scales, spanning from a few hundred nanometers to several micrometers. Both helium plasma exposed W samples are observed to undergo retarded softening up to a depth of a few hundred nanometers from the surface, compared to when the metal may be recrystallized by simple heating, without any plasma exposure.

I2DM: A Monte Carlo framework for ion irradiation on two-dimensional materials

Recent years have witnessed a surge of research on the structure, property and performance engineering of two-dimensional (2D) materials by ion irradiation. Compared to the 3D counterparts, 2D systems exhibit drastically different and even counter-intuitive irradiation response, and an atomic insight into the ion bombardment and defect formation is essential. In this work, we develop a theoretical framework I2DM for simulating ion irradiation on two-dimensional (2D) materials using Monte Carlo (MC) algorithm. I2DM can generate incident ions with adjustable ion species, incident energy, ion fluence and incident angle. Based on binary collision approximation (BCA), the primary collisions, cascade collisions and defect recombination during irradiation process are explicitly described. As output, details on the defect type/yield and morphology of irradiated material are provided. We have performed systematic simulations on three typical 2D structures, including graphene, h-BN, and MoS2 under different ion irradiation conditions, and reveal that the obtained results are in excellent agreement with the available experimental measurements and molecular dynamics data. The developed framework is generally applicable and computationally efficient, highly valuable for understanding the fundamental mechanism of ion irradiation on 2D systems and designing/optimizing low-dimensional structures for nanoelectronics, spintronics, optics, energy storage and environmental protection. Program SummaryProgram Title: I2DM.CPC Library link to program files:https://doi.org/10.17632/pf2pz4fxj3.1.Licensing provisions: GPLv2.Programming language: Python.Supplementary material: Supplementary material is available.Nature of problem: A general MC framework for simulating ion irradiation on 2D materials; calculate the energy loss by nuclear stopping and electronic stopping; simulate primary/cascade collisions and defect recombination; predict defect type/yield and morphology of 2D target.Solution method: This framework uses BCA to describe nuclear stopping for the irradiation process; the energy loss by electronic stopping is computed by a semiempirical model combining Oen-Robinson model and Lindhard-Scharff model; simultaneous collision is included for describing many-body interaction; capture radius is introduced to simulate defect recombination.

N-induced antibacterial capability of ZrO2-SiO2 glass ceramics by ion implantation

Periodontal disease caused by bacterial accumulation is a critical issue affecting the longevity of related materials and implants. Enhancing the antibacterial properties of glass ceramics remains a significant challenge. Due to their excellent mechanical properties, ZrO2-SiO2 glass ceramics have shown great potential in dental restoration. Here, to endow ZrO2-SiO2 glass ceramics with antibacterial properties, nitrogen ion implantation was performed to modify their surfaces. The effects of nitrogen fluence on the microstructural, mechanical and antibacterial properties were investigated. The results showed that phase transformation from tetragonal to monoclinic phase occurred after ion implantation. Surface hardening was observed in the sample under the low fluence ion implantation. Partial amorphization and blistering were observed at the highest fluence of 6.0 × 1017 ions/cm2. XPS analysis revealed that the implanted nitrogen ions mainly form O-Zr-N, N-Si-O and Si-N bonds. Staphylococcus aureus testing showed that the antibacterial properties of ZrO2-SiO2 glass ceramics can be enhanced after implantation, which may be attributed to the formation of reactive nitrogen species. The results show that nitrogen implantation can enhance the antibacterial properties of ZrO2-SiO2 glass ceramics without compromising their mechanical properties.

Temperature-dependent optical absorption spectroscopy of ion irradiated silicon carbide epilayers on silicon

Transmission optical absorption spectra of ion-irradiated 3C-SiC epitaxial films on a silicon substrate are measured in the visible-near infrared range from room temperature down to about 10 K. These data show strong interference fringe patterns on top of the silicon absorption edge at about 10,460 cm1 which limits the transmittance of the samples. The radiation damage by 2.3-MeV Si+ and 3.0-MeV Kr+ ions is studied by following the impact of ion irradiation on these transmission spectra as a function of ion fluence and at various temperatures. The temperature dependence of the optical gap of silicon is deduced from the evolution of the fundamental absorption edge and that of the refractive index of SiC is deduced from the evolution of fringe spacing. The low temperature measurements evidence the shrinkage of band gap of silicon which is assigned to the gradual amorphization of the ion-implanted zone of the substrate as a function of fluence. These new results bridge a gap in the data on the properties of ion-induced damage in silicon carbide and silicon.

Creation of color centers in MgF2 single crystals by swift heavy ions: Energy loss and fluence dependence

Ion-solid interaction leads to significant modifications in the surface and bulk of different materials. MgF2 of a rutile crystalline structure is an important optical material for a large variety of applications. The single crystals were irradiated with energetic heavy ions of various kinetic energies and fluences. After irradiation, we utilized optical spectroscopy to study the ion-induced defects and their evolutions as a function of ion beam parameters. The absorption spectra show the creation of different types of ion-induced defects, namely F-, F2-, and F3-centers. The concentrations of the observed color centers as well as their creation efficiency are studied in terms of ion energy loss and fluence. The results are of high importance for understanding the degradation of optical materials in space environments.

State primary standard for units of absorbed dose and absorbed dose rate of photon, electron, proton radiation and in carbon ion beams, quantity, fuence, fux density and energy of particles in proton beams and heavy charged particles GET 38-2024

The problem of ensuring the accuracy and traceability of the measurement results of the absorbed dose in carbon ion beams, as well as the measurement results of the amount, fluence, flux density and energy of particles in proton and heavy charged particles beams is considered. Until now, in practice, these values have been measured only by indirect methods. The lack of approved measuring instruments for the quantities under consideration and the metrological traceability of measurement results of these quantities to standards did not allow achieving consistency of measurement methods used in practice and confirming the reliability of the results obtained. To solve this problem, three measuring complexes have been developed and created, which are included in the State Primary Standard of units of absorbed dose and absorbed dose rate of photon, electron, proton radiation and in carbon ion beams, quantity, fluence, flux density and energy of particles in proton and heavy charged particles beams GET 38-2024. The measuring complex for reproducing the unit of absorbed dose in carbon ion beams consists of an adiabatic calorimeter, a thermostating system, a data collection and processing system and a vacuum pumping station. To reproduce the unit of energy of protons and heavy charged particles, a complex has been implemented, which includes a total absorption calorimeter, a data collection and processing system, a vacuum pumping station and a particle count determination system based on the use of a Faraday cup. To reproduce the units of fluence and particle flux density in proton and heavy charged particles beams, a measuring complex has been created containing a Faraday cup, a set of collimators and a low current meter. The schemes, the principles and the results of studies of the metrological characteristics of the developed measuring complexes are described. The results are relevant for the field of radiation therapy and radiation resistance tests of the electronic component base used in the space industry.

Investigation the structural and surface characteristics of irradiated flexible polymeric nanocomposites films

This study is to investigate the surface and structural characteristics of the pure and irradiated novel PEO/NiO composite by subjecting the films to argon ions with different ion beam fluencies. The structural characteristics were studied by the EDX and FTIR techniques, while the surface was investigated by SEM technique. The FTIR showed a notable decrease in the peak intensity for the bombarded composite, due to the functional groups with hydrophilic characteristics and the occurrence of chain scission processes. The PEO/NiO composite demonstrates a consistent structure without any nanoparticle clusters, as depicted in the SEM image of PEO/NiO. Moreover, the electrical conductivity for the pure and the irradiated samples were determined. Exposing the composite PEO/NiO to a fluence of 15×1016 ions.cm-2, increasing the conductivity from 7.5×10–8 S/cm to 8.4×10–7 S/cm. By increasing ion fluence from 5×1016 to 15×1016 ions.cm-2. The contact angle is decreased from 81.15o to 72.22o for water, while is decreased from 74.32o to 62.20o for diiodomethane. Moreover, the surface wettability and the adhesion force were determined from the data of the contact angle. The work of adhesion of water increases from 84.37 to 94.16 mJ/m2 and for dioodomethane from 64.52 to 74.49 mJ/m2 , respectively, by increasing ion fluence from 5×1016 to 15×1016 ions.cm-2. This suggests that, in comparison to a unirradiated surface, the increase in 𝑊𝑊𝑎𝑎 is the result of surface cleanliness following radiationThe results of this study show the opportunities for utilizing these irradiated materials in the fields of coating and printing applications.

Argon Ion Implantation as a Method of Modifying the Surface Properties of Wood-Plastic Composites.

Wood-plastic composites (WPCs) combine the properties of plastics and lignocellulosic fillers. A particular limitation in their use is usually a hydrophobic, poorly wettable surface. The surface properties of materials can be modified using ion implantation. The research involved using composites based on polyethylene (PE) filled with sawdust or bark (40%, 50%, and 60%). Their surfaces were modified by argon ion implantation in three fluencies (1 × 1015, 1 × 1016, and 1 × 1017 cm-2) at an accelerating voltage of 60 kV. Changes in the wettability, surface energy, and surface colour of the WPCs were analysed. It was shown that argon ion implantation affects the distinct colour change in the WPC surface. The nature of the colour changes depends on the filler used. Implantation also affects the colour balance between the individual variants. Implantation of the WPC surface with argon ions resulted in a decrease in the wetting angle. In most of the variants tested, the most significant effect on the wetting angle changes was the ion fluence of 1 × 1017 cm-2. Implantation of the WPC surface also increased the surface free energy of the composites. The highest surface free energy values were also recorded for the argon ion fluence of 1 × 1017 cm-2.

Accumulation of oxygen interstitial-vacancy pairs under irradiation of corundum single crystals with energetic xenon ions

Single crystals of α-Al2O3 with broad sides oriented perpendicular to the c crystal axis have been irradiated by 231-MeV xenon ions with fluence varying from 5 × 1011 to 1014 ions/cm2. The spectra of radiation-induced optical absorption (absorption of a pristine crystal is subtracted) have been decomposed into Gaussians serving as a measure of oxygen-related Frenkel defects (interstitial-vacancy pairs). The concentration of all structural defects considered – vacancy-type F and F+ centers as well as oxygen interstitials – continuously increases with ion fluence. Therefore, radiation-induced origin of elementary absorption bands at 5.6 and 6.6 eV tentatively ascribed earlier to charged and neutral oxygen interstitials has been proved for the first time. The concentrations of charged interstitials (in the form of superoxide ions) have been directly determined by the EPR method. The evolution of cathodoluminescence bands typical of self-trapped excitons (VUV band at 7.6 eV) and F-type defects (bands peaked around 3.0 and 3.8 eV) with the rise of Xe-ion-irradiation fluence has been measured and analyzed.

Swift heavy ions induced transformations in the structural and magnetic properties of Co/Pt multilayer thin films for magnetic storage applications

The integration of CoPt nanoparticles into an insulating matrix has garnered significant attention in material science, nanotechnology, and electronic engineering, particularly for their potential use in magnetic storage media. Precise control over the size, shape, and ordering of these nanoparticles is crucial. This study investigates the impact of swift heavy ion irradiation (120 MeV Ag+9) with varying ion fluences (1 × 1013 and 3 × 1013 ions/cm2) on the structural and magnetic properties of sputter-deposited Co/Pt multilayer thin films on quartz substrates. X-ray diffraction (XRD) analysis of the pristine samples reveals the presence of an FCC-structured CoPt alloy. In contrast, films irradiated with a fluence of 1 × 1013 ions/cm2 exhibit superlattice peaks (001) and (110), indicative of L10-structured CoPt alloy, whereas films subjected to 3 × 1013 ions/cm2 retain the FCC structure. This suggests that a fluence of 1 × 1013 ions/cm2 promotes ordering, while 3 × 1013 ions/cm2 induces disordering. Selected area electron diffraction (SAED) patterns from TEM confirm these structural transitions, while SQUID magnetometry reveals an increase in coercivity at 1 × 1013 ions/cm2, followed by a reduction at 3 × 1013 ions/cm2, consistent with the observed structural changes. These results demonstrate that carefully controlled ion fluences can effectively tailor the structural and magnetic properties of Co/Pt multilayers, enhancing their suitability for advanced magnetic storage applications.

Simulated Solar-wind-induced Space Weathering of Olivine Powders: Spectral Alterations in the Ultraviolet, Visible, and Near-infrared

Bombardment by solar wind ions is one of the main drivers of space weathering on airless bodies. Here, we simulate the solar-wind-driven spectral alteration of loosely packed olivine powders by irradiation with 1.2 keV helium ions (He+). We measured the reflectance spectra of the olivine powder in the ultraviolet–visible–near-infrared (UV–Vis–NIR) wavelength range (0.2–2 μm) as a function of ion fluence. In the Vis–NIR range, we observed spectral darkening, absorption band shallowing, and spectral reddening, in agreement with lunar-style space weathering and previous laboratory studies. In the UV–Vis, spectral darkening was also observed. However, a spectral bluing took place at wavelengths below 400 nm. As the simulated space weathering progressed, the spectral slopes shifted from steep-UV/shallow-NIR slopes to shallow-UV/steep-NIR slopes. Moreover, the change in the UV slope was almost 10 times larger than in the NIR, supporting the hypothesis that the UV spectral slope could be an earlier indicator of space weathering.

Exfoliated layered nanosheets of orthorhombic SnS, subjected to 90 MeV carbon ion irradiation

Derived through liquid phase exfoliation, the irradiation response of nanoscale, exfoliated tin sulfide (SnS) systems are being reported in this work. The SnS nanosheets were exposed to 90[Formula: see text]MeV [Formula: see text] ion beams across fluences ranging from [Formula: see text] to [Formula: see text][Formula: see text]ions/cm2. With an electronic energy loss ([Formula: see text]) of [Formula: see text]56[Formula: see text]eV/Å, dominating over the nuclear energy loss ([Formula: see text]), the average crystallite size of the irradiated samples displayed an augment when compared to its pristine counterpart. Exhibiting an orthorhombic crystal structure, structural analyses of both pristine and irradiated samples were conducted via X-ray diffraction (XRD) technique. Raman analysis has manifested some modifications in the SnS nanosystem upon radiation exposure, particularly with higher fluences causing local structural disorder and amorphization of the material. Moreover, morphological changes in the irradiated SnS samples were examined using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), with AFM images revealing an increase in the root mean square (RMS) roughness corresponding to ion fluence. Furthermore, swift heavy ion (SHI) irradiation prompted a non-rectifying Ohmic [Formula: see text] characteristics and altered the electrical conductivity of the SnS nanosheets.

Swift heavy ion irradiation-induced enhancement of spin–orbit torque efficiency in Pt/Co/Ta trilayers

Increasing the efficiency of spin–orbit torque (SOT) is of great interest in applications for magnetic random access memory and logic devices due to decreased energy consumption. Here, we present that the SOT efficiency of Pt/Co/Ta films with perpendicular magnetic anisotropy can be improved by swift high-energy heavy Fe11+ ion irradiation, which is an effective method to alter crystallinity, interface roughness, and defects in ferromagnet/heavy metal heterostructures. Specifically, the Pt/Co/Ta films show an optimal SOT efficiency at ion fluence around 1.0 × 1013 ions/cm2 with the largest spin Hall angles reaching 0.59, which is the largest improvement of spin Hall angle by ion irradiation compared to previous studies using light ions. We demonstrate that the increase in SOT efficiency arises from structural changes in the Pt layer due to ion irradiation-induced damage effects at proper fluence, while the decrease in SOT efficiency is mainly attributed to the restoration of Pt crystallinity induced by beam-heating effects at high fluence. This work demonstrates that an appropriate ion irradiation process could improve the SOT efficiency and the spin Hall angle, thereby providing a way to develop future SOT-based spintronic devices.

Fractal formalism in crystallized-Ge via Al induced crystallization under ion irradiation

The fractal characterization of polycrystalline-Ge formed via Al induced crystallization under ion irradiation is presented. The polycrystalline (p-) Al (50 nm)/amorphous (a-) Ge (50 nm) is irradiated using 1000 keV Xe+ ions with fluences of 7 × 1014 ions/cm2, 3 × 1015 ions/cm2 and 1 × 1016 ions/cm2 followed by post-thermal annealing at 200 °C. The pristine (i.e., as-prepared) sample is also thermally annealed for comparison purposes. The X-ray diffraction measurement confirms the crystallization of Ge after thermal annealing in both pristine and ion irradiated samples whereas only ion irradiation does not show any crystallization of Ge. The optical micrograph and field emission scanning electron microscopy (FE-SEM) images show dotted like structures on the surface of the film which are found to increase with increasing ion fluence. The Rutherford backscattering spectrometry and energy dispersive X-ray spectroscopy confirm the layer exchange phenomena at the interface in the p-Al/a-Ge bilayer system with Ge crystallization. The fractal analyses have been carried out on FE-SEM images which confirms the Ge fractals formation due to crystallization of Ge followed by layer exchange. The fractal dimension and hurst exponent are calculated and found that the surface roughness decreases with increasing ion fluence up to the fluence of 3 × 1015 ions/cm2 and then increases at higher fluence.

Effects of implantation of laser produced Ni plasma ions on CR-39 correlated with surface, structural, optical and electrical properties of polymer

Laser produced plasma ions implantation has a great potential to change various characteristics of the polymer after irradiation, such as, surface, structural, optical and electrical properties. For this purpose, polymer CR- 39 is implanted by laser produced Ni plasma ions at various fluences ranging from 75 × 1013 to 95 × 1016 ions/cm2. The ion energy estimated by Thomson parabola technique using CR-39 detectors was 540 KeV. Digital optical microscopic analysis illustrates the formation of granular morphology for all ion fluences. However, at the maximum fluence (95 × 1016 ions/cm2), distinct and well organized grains with sub-granular morphology are observed. Confocal microscopic analysis shows the development of micro/nano sized caters, voids, ion tracks, clusters and bumps for various fluences of Ni ions ranging from 75 × 1013 to 60 × 1015 ions/cm2. Whereas, at the maximum ion fluence (95 × 1016 ions/cm2), hillock like features are observed. Raman spectroscopy analysis shows the formation of carbonaceous structures along with new bonds of Ni–CO in implanted CR-39. Reduction in transmittance value from 92.2% to 60.8% is observed with increase in ion fluence from 75 × 1013 to 95 × 1016 ions/cm2. The electrical conductivity of implanted CR-39 increases by increasing the ion fluence. Formation of conductive layer and carbonaceous structures are considered to be accountable for improvements in electrical conductivity of implanted target polymer. The observed stopping power or Linear Energy Transfer (LET) of 540 KeV Ni ions in CR-39 is 72.88 eV/Ǻ and their corresponding depth is 686 nm.

Comparative Analysis of 50 MeV Li3+ and 100 MeV O7+ Ion Beam Induced Electrical Modifications in Silicon Photodetectors

This article investigates the impact of 100 MeV O7+ and 50 MeV Li3+ ions on Silicon Photodetectors, focusing on their electrical characteristics with similar Sn/Se ratios. Elevated ion fluences led to a significant rise in the ideality factor “n”, indicating the presence of Generation-Recombination (G-R) current due to introduced defects, especially those with deep energy levels in the forbidden gap acting as G-R centers. While Ideality factor (n) values decreased for oxygen ions at maximum fluence, they increased for lithium ions, reflecting consistent patterns in series resistance (Rs) and reverse leakage current (IR), attributed to ion-induced defects. Oxygen ions showed a monotonic variation in Rs, whereas lithium ions exhibited a slight reduction at maximum fluence, possibly due to defect annihilation. Despite differing Se values, 50 MeV Li3+ ions demonstrated improved device characteristics, suggesting potential defect annihilation. The ratio of Sn to Se indicated comparable damage contributions from nuclear and electronic energy. Additionally, TRIM computations revealed non-uniform damage distributions, with ions penetrating deep into the substrate, away from the n+/p junction.