Swift Heavy Ion Beam Irradiation Research Articles

Recrystallization effects in spray-pyrolyzed Nb2O5 thin films induced by 100 MeV O7+ swift heavy ion beam irradiation

In this work, the influence of 100 MeV O7+ high energy swift heavy ion beam irradiation at varied fluences on the modification of properties of spray-deposited thin niobium pentoxide (Nb2O5) film is reported. The XRD patterns indicate tetragonal structure for pristine polycrystalline Nb2O5 film and partial amorphous nature for the irradiated samples in corroboration with the Raman spectra of the respective samples. The crystallite size is observed to reduce overall compared to that of the pristine film, however, a peaking is observed for 5x1012 ions/cm2 fluence within the irradiated films which is due to the high energy irradiation-induced defect formation and recrystallization effects. It is important to note that the defect density increases with fluence and recrystallisation occurs at 5x1012 ions/cm2, with further amorphization induced at much higher fluences. The generation of additional defect levels lowers the optical band gap. The direct and indirect band gaps were found to reduce upon irradiation compared to that of the pristine Nb2O5 film. The atomic force microscopic analysis reveals decrease in surface roughness of the irradiated samples from 5.9 nm to 10.1 nm compared to the pristine sample. Oxygen ion beam changes their morphology into network-like structures in a controllable manner which mainly depends on electronic energy loss occurring within the Nb2O5 lattice. Variations in transport parameters measured using Hall effect reveal that lower fluence yields less damage accumulation and does not cause significant change in properties of the sample. As fluence increases, vivid modifications originate from the production of significant density of point defects. At the critical fluence, recrystallisation is observed. These results are discussed in detail using the calculated parameters like crystallite size, Urbach energy, defect density and by correlating them with the observed optical and electrical data obtained from different techniques.

High energy (MeV) ion beam induced modifications in Al2O3-ZnO multilayers thin films grown by ALD and enhancement in photoluminescence, optical and structural properties

Atomic Layer Deposition (ALD) is employed for the growth of nanometric conformal layers on distinct substrates. In the present work, we demonstrated the attainable consequences on the examination of optical and structural peculiarities of pristine and SHI (swift heavy ions) irradiated ultrathin multilayer samples of Al2O3-ZnO fabricated on glass and silicon substrates using the technique based on ALD. Multilayer Al2O3-ZnO specimens were irradiated with 100 MeV SHI in the fluence range of 1E12 to 5E13 ions/cm2. For a better conception of the impact of ion beam irradiation with high energy on structural parameters like strain, dislocation density, crystallite size was demonstrated by X-Ray Diffraction (XRD). The coefficient of absorption was used to demonstrate the changes that occur in optical bandgap, urbach energy, skin depth and optical density with the function of ion fluence. Photoluminescence (PL) spectra were investigated at room temperature to comprehend the mechanism of changes in peak shifting and intensity of broad and strong emission luminescence spectra at excitation wavelengths of 300 nm were noteworthy. To evaluate the thickness, crystalline quality and quantitative composition of the elements Rutherford Backscattering Spectroscopy (RBS) employing utilizing the He2+ with high energy was used and reported. Regulation of optical peculiarities through swift heavy ion beam irradiation explores extensive opportunities for Al2O3-ZnO multilayer nanofabrication in optoelectronics domain.

Effect of 100 MeV Ni ion irradiation on CdZnTe thin films

Modification of semiconductor thin films by Swift Heavy Ion (SHI) beam irradiation is a unique technique for property improvement. In the present investigation, Cadmium Zinc Telluride (CZT) thin films of thickness 100 nm are deposited on glass substrates by the thermal evaporation method. These films are irradiated with 100 MeV Ni ion beams at a fluence of 1×1012 ions/cm2 and 5×1012 ions/cm2. The SHIinduced surface modifications are studied by Atomic Force Microscopy (AFM). The structural properties are investigated using X-ray diffraction (XRD) technique. Optical characterization is carried out using UV–Vis spectroscopy. The SHI irradiation on CZT films results in grain fragmentation. Phase transformation and widening of bandgap is also observed after SHI irradiation. The SHIinduced property modifications are explained in the framework of ‘coulomb explosion and thermal spike model’.

Swift heavy ion beam modified MoS2- PVA nanocomposite free-standing electrodes for polymeric electrolyte based asymmetric supercapacitor

Swift heavy ion (SHI) beam irradiation technique is one of the sophisticated techniques used for modifying material properties to design efficient devices. In this report, the casted MoS2- PVA nanocomposite films have been irradiated with 80 MeV C6+, 100 MeV Si9+, and 120 A g9+ ion beams to achieve enhanced conductivity and have been exploited as an electrode material for asymmetric supercapacitor. PVDF-HFP: TPAI gel polymer electrolyte having 3 wt.% TPAI content showed the highest conductivity and was chosen for the iodide redox gel polymer electrolyte system. The pristine MoS2-PVA nanocomposite films having an electrical conductivity of 2.5E-5 S/cm exhibited specific capacitance of 65.27 F/g whereas the films irradiated with 120 MeV Ag9+ ion beams showed an electrical conductivity of 9.7E-3 S/cm and enhanced specific capacitance of 186.67 F/g. The enhanced capacitance is attributed to the high current density generated due to the increased conductivity of the electrodes.

Tailoring the properties of spray deposited V2O5 thin films using swift heavy ion beam irradiation

Swift heavy ion (SHI) beam irradiation can generate desirable defects in materials by transferring sufficient energy to the lattice that favours huge possibilities in tailoring of materials. The effect of Ag15+ ion irradiation with energy 200 MeV on spray deposited V2O5 thin films of thickness 253 nm is studied at various ion doses from 5 × 1011 to 1 × 1013 ions/cm2. The XRD results of pristine film confirmed orthorhombic structure of V2O5 and its average crystallite size was found to be 20 nm. The peak at 394 cm−1 in Raman spectra confirmed O–V–O bonding of V2O5, whereas 917 cm−1 arise because of distortion in stoichiometry by a loss of oxygen atoms. Raman peaks vanished completely above the ion fluence of 5 × 1012 ions/cm2. Optical studies by UV–Vis spectroscopy shows decrement in transmittance with an increase in ion fluence up to 5 × 1012 ions/cm2. The red shift is observed both in the direct and indirect band gaps until 5 × 1012 ions/cm2. The surface topography of the pristine film revealed sheath like structure with randomly distributed spherical nano-particles. The roughness of film decreased and the density of spherical nanoparticles increased upon irradiation. Irradiation improved the conductivity significantly for fluence 5 × 1011 ions/cm2 due to band gap reduction and grain growth.

Enhanced electrical properties of few layers MoS2-PVA nanocomposite film via homogeneous dispersion and annealing effect induced by 80 MeV Carbon6+ swift heavy ion irradiation

Swift heavy ion beam irradiation is an advanced method to tune or modify the properties of a wide class of materials up to an electronic level. High-performance polymer nanocomposites are a class of materials that have drawn immense scientific attention due to their remarkable properties in the field of organic electronics. In this work, MoS2 nanosheets are first synthesized via solvent assisted exfoliation and then incorporated as filler in Polyvinyl alcohol matrix. The free-standing polymer nanocomposite film was irradiated using 80 MeV Carbon swift ion beam at 1 × 1010 ions/cm2, 1 × 1011 ions/cm2 and 3 × 1011 ions/cm2 to induce structural, spectroscopic and electrical changes due to high deposition of energy. XRD and Raman reveal the annealing effect at low fluence of at 1 × 1010 ions/cm2. Upon Swift heavy ion irradiation, a remarkable rise in the conductivity for application in organic electronics, from 2.58E-5 S/cm to 2.43E-3 S/cm at 1 × 1010 ions/cm2 has been observed. The conductivity continues to rise with increase in ion fluence and attains a value of 4.92E-3 S/cm at 3 × 1011 ions/cm2. This is attributed to the formation of conductive tracks and homogeneous dispersion upon SHI irradiation in accordance with Thermal spike model.

Microstructure of SiC fibers by swift heavy ion beam irradiation

In this paper, third generation SiC fiber material irradiated with the 410 MeV energy of [Formula: see text] ion at 173 K was analyzed by Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscope (TEM). Raman spectroscopy, TEM and XRD data show modifications in the local structure of irradiated SiC fibers. Although highly disordered SiC grains were observed in appearance, no evidence of amorphization was found. After the Sn ions irradiation and XRD, two diffraction peaks disappeared, which showed that the rich Si and C could be further combined in [Formula: see text] ions/cm2 dose irradiation condition. This result mainly explains the electron damage and the nuclear damage process in SiC fibers, leading to the recombination or migration of defects.

200 MeV Ag15+ swift heavy ion beam induced property modifications in Nb2O5 thin films by fluence variation

Swift Heavy Ion beam irradiation is capable of inducing a variety of modifications on the properties of thin films by high energy deposition. The Nb2O5 thin films deposited by spray pyrolysis technique were then irradiated with 200 MeV Ag15+ ions at fluence ranging from 5 × 1011 to 1 × 1013 ions/cm2. The thickness of the deposited film was 308 nm and the irradiated area was 1x1 cm2. The XRD pattern of the pristine film confirmed the tetragonal structure of Nb2O5. Upon irradiation, peak intensity decreased significantly and some peaks vanished due to irradiation induced defects. The subtle Raman peaks around 960, 223, and 126 cm−1 corresponds to edge shared octahedra, T2u mode and Nb–Nb vibration respectively. After irradiation, complete suppression of vibration modes was observed except for 1 × 1012 fluence. For the 1 × 1012 ions/cm2 fluence, Raman modes reappear with increased intensity due to irradiation induced recrystallization. Optical transmittance spectra showed a decreased trend as fluence increased due to the formation of optically absorbing centers. Both the direct and indirect band gaps showed a systematic red shift. The pristine AFM image revealed agglomeration of particles while a network like structure was observed after irradiation. Results of transport properties studied for both pristine and irradiated films at room temperature by Hall effect are also presented.

Investigation of structural and electrical properties of pristine and 200 MeV Ag15+ ion irradiated 3 wt% ‘Li’ doped WO3 thin films

Swift Heavy Ion (SHI) beam irradiation has been used as an experimental technique to modify the material properties through the interaction of the ion beam with the target material. In this work, the properties of the pristine and 200 MeV Ag15+ ion beam irradiated lithium (3 wt%) doped WO3 (tungsten trioxide) thin films are reported. These thin films were spray deposited onto ITO coated glass substrates at 400 °C with thickness around 55 nm and irradiated with the 200 MeV Ag15+ ion beam at a fluence of 5 × 1012 ions/cm2. The XRD pattern of pristine film confirmed textured growth along the (211) plane with tetragonal phase, while the irradiated film was partially amorphous. Raman modes at higher wavenumbers 708 cm−1 and 806 cm−1 belong to W–O stretching modes, whereas modes at lower wavenumbers 133 cm−1 belong to lattice mode and 265 cm−1 are associated with W–O bending modes for pristine film. Upon irradiation, all the Raman modes vanished due to irradiation induced amorphization. The optical transparency of the film upon irradiation decreased significantly, and band gaps showed a red shift. The atomic force microscopy (AFM) images of pristine film surfaces were homogeneous, smooth and free from holes with small grains, whereas ion irradiated films exhibited isolated flattened particles of varying size on the surface. Room temperature transport properties were also measured using Hall effect for both the pristine and irradiated films.

Effect of 200 MeV Ag15+ ion beam irradiation at different fluences on WO3 thin films

The physical properties of thin films can be modified by swift heavy ion (SHI) beam irradiation of the target material. Spray-deposited tungsten trioxide (WO3) thin films of thickness 89 nm were irradiated with 200 MeV Ag15+ ion beam at various fluences of 5 × 1011, 1 × 1012, 5 × 1012, and 1 × 1013 ions/cm2. The X-ray diffraction pattern of the pristine film was orthorhombic, while the irradiated film became amorphous at different fluences except for 5 × 1012 ions/cm2; this may be due to the re-crystallization effect induced by irradiation. The observed Raman modes for the pristine film were in good agreement with those reported for the irradiated WO3 films. The intensity of Raman peaks decreased upto 5 × 1012 ions/cm2 and vanished completely at further higher fluences. The optical transparency of the pristine film was much higher than that of irradiated ones. Both the direct and indirect band gaps showed a red shift. AFM data revealed significant surface modifications after irradiation. Transport properties were also studied for both the pristine and irradiated films by the Hall effect. A decrease in resistivity was observed with the increase in fluence. These results are discussed in this paper.

Swift heavy ion irradiation induced modifications in structural, microstructural, electrical and magnetic properties of Mn doped SnO2 thin films

In this paper, we have presented the effect of swift heavy ion beam irradiation on the structural, microstructural, electrical and magnetic properties of Sn0.9Mn0.1O2 thin films. The structural and electrical results have been interpreted by using properties of native or point defects, whereas the magnetic and morphological variations have been explained in terms of the conductivity of material. Efforts have been made to summarize the properties of all possible charged and neutral point defects (VSn4-,Sni4+,VO0,Oi2-,SnO4+,OSn2-,HO+) and afterwards from the correlation between experimentally-observed and theoretically-calculated results various interesting conclusions have been drawn.

Ion beam-induced modification of structural and optical properties of MgTiO3 nanocrystalline thin films

ABSTRACTMgTiO3 thin films were deposited on an amorphous silicon dioxide substrate by the RF magnetron sputtering method by varying the argon and oxygen mixing percentage. These pristine thin films were subjected to thermal annealing at a temperature of 700°C and subsequently two sets of crystalline thin films were irradiated using 100 MeV Au8+ ions at a fixed fluence of 2 × 1013 ions/cm2. XRD spectra reveal that the crystallite size reduces from 21 to 15 nm and crystallinity also decreases drastically after irradiation. AFM images show significant variation in the surface morphology upon irradiation. Optical studies suggest that the band gap as well as the refractive index are both reduced due to SHI irradiation. Ion beam induced modification of the structural, morphological and optical properties of MgTiO3 thin films and the possible mechanisms responsible for variation of the properties of MgTiO3 due to swift heavy ion beam irradiation have been discussed in detail.

Shaping of Au nanoparticles embedded in various layered structures by swift heavy ion beam irradiation

We present a novel method to extend the ion-beam induced shaping of metallic nanoparticles in various layered structures. Monodisperse Au nanoparticles having mean diameter of 30nm and their ion-shaping process is investigated for a limited number of experimental conditions. Au nanoparticles were embedded within a single plane in various layered structures of silicon nitride films (Si3N4), combinations of oxide-nitride films (SiO2-Si3N4) and amorphous silicon films (a-Si) and have been sequentially irradiated at 300K at normal incidence with 50 and 25MeV Ag ions, respectively. Under irradiation with heavy Ag ions and with sequential increase of the irradiation fluence, the evolution of the Au peak derived from the Rutherford Backscattering Spectrometry show broadening in Au peak, which indicates that the Au becomes distributed over a larger depth region, indicative of the elongation of the nanoparticles. The latter is observed almost for every layer structure investigated except for Au nanoparticles embedded in pure a-Si matrix. The largest elongation rate at all fluences is found for the Au nanoparticles encapsulated in pure Si3N4 films.For all irradiation energy applied, we again demonstrate the existence of both threshold and saturation fluences for the elongation effects mentioned.

Nickel ion induced modification in the electrical conductivity of Cu nanowires

Swift heavy ion beam irradiation induced modifications in metals has lead to a curiosity for evaluating the depth dependence of damage process that could be the source of deviation in their physical properties. In this context, the present work aims to study the conduction of electrons in pre- and post-ion irradiated copper nanowires. Cu nanowires of 80 nm diameter were synthesized using track-etched membranes via template-assisted electrodeposition technique. Nickel (Ni12+) ion beam of 160 MeV energy was made incident on cylindrical Cu nanowires along their axis at Inter University Accelerator Centre (IUAC) at New Delhi, India. X-ray diffraction pattern of pre- and post-ions irradiated Cu nanowires inveterate the polycrystalline nature of nanowires with cubic lattice geometry. The investigation of I–V characteristics indicated that irradiated Cu nanowires at various fluence sustained the ohmic behavior with different slopes except last fluence. Variation in transportation of electrons through the grain boundaries and increase in the amplitude of lattice vibrations may be responsible for the alteration of the electrical conductivity of the copper nanowires.

High energy Oxygen ion irradiation effects on thin films of Sr[(Mg0.32Co0.01)Nb0.67]O3

Present paper gives detailed investigation of Sr[(Mg0.32Co0.01) Nb0.67]O3 [SMCN] thin films deposited on ITO coated glass substrate using Pulse laser deposition technique. In order to probe the stability of SMCN under high energy ion irradiation, swift heavy ion (SHI) beam irradiation experiments are performed using 100MeV O7+ ion beams. The effect of irradiation on films, fluence of 1×1012 and 1×1013 ions/cm2, are investigated by X- ray diffraction (XRD), UV-Vis spectroscopy, atomic force microscopy (AFM) and dielectric measurements. It reveals polycrystalline and uniform columnar growth in as- deposited films. Ion irradiation leads to partial amorphization as observed in AFM results. We have also observed drastic reduction in dielectric loss tangent (Tanδ) values. At 1×1013 fluence film shows very low values of tanδ~0.008 at room temperature. The temperature coefficient of dielectric constant (TCK) after irradiation has drastically fallen to 1/2 of its value in unirradiated film. Optimization of critical irradiation parameters may lead to its applicability in devices.

SHI induced enhancement in green emission from nanocrystalline CdS thin films for photonic applications

Intense green emission is reported from nanocrystalline CdS thin films grown by pulsed laser deposition. The effect of ion beam induced dense electronic excitation on luminescence property of CdS films is explored under irradiation using 70MeV 58Ni6+ ions. It is found that swift heavy ion beam irradiation enhances the emission intensity by an order of 1 and broadens the emission range. This feature is extremely useful to enhance the performance of different photonic devices like light emitting diodes and lasers, as well as luminescence based sensors. To examine the role of energy relaxation process of swift heavy ions in creation/annihilation of different defect levels, multi-peaks are fitted in photoluminescence spectra using a Gaussian function. The variation of contribution of different emissions in green emission with ion fluence is studied. Origin of enhancement in green emission is supported by various characterization techniques like UV–visible absorption spectroscopy, glancing angle X-ray diffraction, micro-Raman spectroscopy and transmission electron microscopy. A possible mechanism of enhanced GE due to ion beam irradiation is proposed on the basis of existing models.

Effects of swift heavy ion beam irradiation on the structural and morphological properties of poly(methacrylic acid) cross-linked gum ghatti films

Poly(methacrylic acid) (PMAA) chains were cross linked onto the backbone of gum ghatti (Gg) using N,N′-methylene-bis-acrylamide (MBA) and ammonium persulfate (APS) as a cross linker-initiator system in a vacuum oven. The cross linking of the PMAA chains on the polysaccharide backbone was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Later, the cross-linked polysaccharide samples were irradiated at room temperature with 100 MeV O7+ ion beam irradiation at various fluences from 1 × 1011 to 3 × 1012 ions/cm2. We have observed noticeable modifications in the structural and morphological properties after irradiation. The XRD study reveals the gradual decrease in peak intensity with an increase in the ion fluence, which reflected a loss of crystallinity after irradiation. The FTIR spectra show a decrease in intensity of the typical bands at the higher fluence. Different causes of these modifications are discussed.

Fabrication of planar waveguide in KNSBN crystal by swift heavy ion beam irradiation

We report on the fabrication of the planar waveguides in the KNSBN crystal by using 17MeV C5+ ions at a fluence of 2×1014ions/cm2. After implantation, near surface regions of the crystal, there has a positive extraordinary refractive index (ne) change and the light inside the waveguides can propagate in a non-leaky manner. The two-dimensional modal profiles of the planar waveguides, measured by using the end-coupling arrangement, are in good agreement with the reconstructed modal distributions. The propagation loss for C5+ irradiated waveguide is ∼0.8dB/cm at 633nm and ∼0.72dB/cm at 1064nm. The waveguide gives good confinement of waveguide modes, which exhibits acceptable guiding qualities for potential applications in integrated optics.

Structural and optical properties of porous silicon prepared by anodic etching of irradiated silicon

Porous silicon (pSi) is considered to be a potential material in the field of electronics and optoelectronics because of its strong luminescence in visible and near-infrared region. Swift Heavy Ion (SHI) beam irradiation shows versatile effects on physical and optical properties of porous silicon. The p-type (100) Si was irradiated with 80MeV Ni ions at various fluences ranging from 1×1011 to 5×1013 ions/cm2. The irradiated samples were anodically etched to get porous Si. Field Emission Scanning Electron Microscope (FESEM) images confirm the presence of uniform sponge like surface in pSi layers. The photoluminescence (PL) peak position is found to shift towards the higher wavelength (red shift) by increase in fluence. The increased defect states are expected to be responsible for the observed exponential degradation in PL intensity. The pSi layer thickness is found to decrease with increase in fluence. The refractive index (n) measurements on pSi were consistent with structural and optical measurements. Finally we found that Ni ion irradiation promotes aging effects leading to some observable blue shift in PL.

Structural and optical studies of 100 MeV Au irradiated thin films of tin oxide

Thin films of tin(IV) oxide (SnO2) of 100nm thickness were grown on silicon (100) matrices by electron beam evaporation deposition technique under high vacuum. The thicknesses of these films were monitored by piezo-sensor attached to the deposition chamber. Nanocrystallinity is achieved in these thin films by 100MeV Au8+ using 1pnA current at normal incidence with ion fluences varying from 1×1011ions/cm2 to 5×1013ions/cm2. Swift Heavy Ion beam irradiation was carried out by using 15 UD Pelletron Accelerator at IUAC, New Delhi, India. Optical studies of pristine and ion irradiated thin films were characterized by UV–Visible spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy. Prominent peak at 610cm−1 in FTIR spectrum confirmed the O–Sn–O bonding of tin(IV) oxide. For Surface topographical studies and grain size calculations, these films were characterized by Atomic Force Microscope (AFM) using Nanoscope III-A. Crystallinity and phase transformation due to irradiation of pristine and irradiated films were characterized by Glancing Angle X-ray Diffraction (GAXRD) using Brucker-D8 advance model. GAXRD results show improvement in crystallinity and phase transformation due to swift heavy ion irradiation. Grain size distribution was verified by AFM and GAXRD results. Swift heavy ion induced modifications in thin films of SnO2 were confirmed by the presence of prominent peaks at 2θ values of 30.65°, 32.045°, 43.94°, 44.96° and 52.36° in GAXRD spectrum.