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We study the continuous dependence of the so-called (bivariate) α-fractal function on the parameters such as the scaling function α, net △ of rectangular grid, and the base function s involved in its construction. Furthermore, we establish some results regarding its dimension. [ABSTRACT FROM AUTHOR]

Germanium single crystals were irradiated at room temperature by 1.5 MeV energy germanium ions and high energy silver ions of 100 MeV. Based on the transmission and high-resolution electron microscopic investigations, we present the experimental evidence of complete recrystallization of the amorphized germanium layer, formed by the self-ion-implantation, due to intense electronic excitations generated by the swift Ag ions. This phenomenon is observed at room temperature—far below the solid phase epitaxial growth temperature and that at which low energy ion beam induced epitaxial crystallization takes place. The results are explained in the light of local transient melting due to a high rate of energy deposition by the silver ions and its subsequent cooling. Based on the calculations on thermal spike concept in combination with the nonequilibrium thermodynamics, we obtain a reasonably good estimate for the experimental observation. [ABSTRACT FROM AUTHOR]

We report on MeV heavy ion beam induced epitaxial crystallization of a buried silicon nitride layer. Transmission electron micrographs and selected area diffraction patterns are used to study the recrystallization of an ion beam synthesized layer. We observe complete recrystallization of the silicon nitride layer having good quality interfaces with the top and substrate Si. Recrystallization is achieved at significantly lower temperatures of 100, 150, and 200 °C for oxygen, silicon, and silver ions, respectively. The fact that recrystallization is achieved at the lowest temperature for the oxygen ions is discussed on the basis of the energy loss processes. [ABSTRACT FROM AUTHOR]

We report on swift heavy-ion-beam-induced epitaxial crystallization of a buried Si3N4 layer. We observe good epitaxial crystallization at 200 °C, which is a much lower temperature than that required for the conventional solid phase epitaxial growth. High-resolution transmission electron microscopy and selected area diffraction patterns have been used to study the 100-MeV Ag8+-ion-beam-induced epitaxial growth of the Si3N4 layer. A possible mechanism of recrystallization is discussed on the basis of synergetic effects of electronic and nuclear energy-loss processes along the trajectory of the swift heavy ions at elevated temperatures. [ABSTRACT FROM AUTHOR]

We report on room-temperature synthesis of nanodimensional Au-Ge alloy on Si surface by ion-beam mixing of nanoislands of Au and Ge. Synthesis of such surface nanoalloys could be the basis of making nanodimensional contacts towards miniaturization of microelectronic devices. The nanoislands of Au and Ge were grown by UHV electron beam evaporation technique on Si (100) surface and were irradiated by 1.5 MeV Au2+ ions over a fluence range of 5×1012–1×1015 ions cm-2. High-resolution transmission electron microscopy has been employed to study the formation of Au-Ge alloy in the form of nanoislands. Formation of such surface alloy nanoislands has been discussed in the light of ion-matter interaction in nanometer scale regime. [ABSTRACT FROM AUTHOR]

We report on interface modification in Co/Ge bilayer system using 100 MeV Au7+ ion irradiation at different temperatures and fluences. Irradiation induced changes occurring across the Co/Ge interface are studied by Rutherford backscattering spectrometry and cross-sectional transmission electron microscopy. Although Au irradiation at low temperature does not show any interface mixing, formation of a thin (∼3–4 nm) Co–Ge alloy layer has been observed after room temperature irradiation to a fluence of 1×1014 ions cm-2. This mixing has been discussed on the basis of synergetic effects of nuclear and electronic energy loss processes in the bilayer system. [ABSTRACT FROM AUTHOR]

We report on the formation of a-axis oriented Au[sub 0.6]Ge[sub 0.4] alloy on a Si(100) substrate on 120 MeV Au-ion irradiation of a Au/Ge bilayer and subsequent vacuum annealing at 360 °C. Irradiation-induced changes occurring across the Au/Ge interface were studied using Rutherford backscattering spectrometry. Phase identification was done by x-ray diffraction and the surface morphology of the samples was studied by scanning electron microscopy. Formation of oriented Au[sub 0.6]Ge[sub 0.4] alloy was confirmed by transmission electron microscopy and discussed on the basis of swift heavy ion induced effects followed by thermal annealing. [ABSTRACT FROM AUTHOR]

In this paper we have established some conditions which guarantee the existence of the distance between two subsets of a regular cone metric space. Under these conditions we have given a main result which guarantee the existence of best proximity points for cyclic contraction mappings in regular cone metric space, which extends the earlier result of Haghi et al(2011). [ABSTRACT FROM AUTHOR]

An economic estimation of an autonomous power delivery system constituting different types of non-conventional and renewable energy resources has been performed considering an Indian load demand scenario. The mathematical analysis was done by the application of a modified differential evolution (MDE). The MDE-evaluated total annual costs for the autonomous microgrid system utilizing three sets of distributed energy resources (DERs) have been compared. Solar module and fuel cells as DERs form the first set of DERs; solar module and bio-mass gas-ifier unit as DERs is considered as second set; and fuel cell along with Battery Energy Storage System (BESS) constitute the third set of DERs. Different types of consumers together form the microgrid with optimal supply of power from DERs. The optimal power generation conditions have been obtained pertaining to minimum cost of microgrid system. For the same load demand in microgrid operation, the results, using a hybrid solar-biomass system are found to be most cost effective. A reduction of 6.9% in the annual cost is obtained using the combination of solar module and biomass gasifier unit from that obtained using a solar module fuel cell combination. The corresponding reduction is 10% from that utilizing only fuel cell. [ABSTRACT FROM AUTHOR]

Highlights: [•] This paper deals with study of 500eV Ar-ion induced temporal evolution of ripple morphology on p-Si (100) at room temperature. [•] An angular window of 51°–72.5°, in terms of ion incidence angle, was chosen for this study. [•] Temporal evolution of parallel-mode ripples fits well in the framework of ion induced solid flow model over this entire angular window. [•] We show that the experimentally determined reference timescale (corresponding to the reference angle of 60°) can be used to predict the intrinsic timescales (below which ripple evolution remains in the linear regime) at all other angles. [•] Our approach reveals that calculation of the ion induced stress can be avoided for calculation of the intrinsic timescales. [ABSTRACT FROM AUTHOR]

An economic evaluation of a network of distributed energy resources (DERs) forming an autonomous power delivery system in an Indian scenario has been made. The mathematical analysis is based on the application of a real valued cultural algorithm (RVCA). The RVCA-evaluated total annual costs for the autonomous microgrid system utilizing both solar module and fuel cells as DERs and solar module and bio-mass gassifier unit as DERs have been compared. Different types of consumers together form a microgrid with the optimal supply of power from DERs. The optimal power generation conditions have been obtained pertaining to minimum cost of microgrid system. The results for different loading scenarios, using hybrid solar—biomass gassifier unit are found to be more cost competitive. A reduction of 8.1% in the annual cost is obtained using solar module-biomass gassifier unit to that using solar module-fuel cell for the same load demand in microgrid operation. [ABSTRACT FROM PUBLISHER]

Spinel MgIn2O4 thin films were deposited on quartz substrates by the chemical spray pyrolysis technique using metal organic precursors at 450°C. Energetic 1.5 MeV Li+ ions were implanted to various fluences of 1013, 1014 and 1015 ions/cm2 onto insulating MgIn2O4 films using a 9 SDH-2, NEC, 3MV accelerator to modify the material properties and surface nature. X-ray diffraction analysis was carried out to identify the changes in the crystallinity and grain orientations before and after implantations. Before implantation, the grains of polycrystalline MgIn2O4 were randomly oriented [(222), (311), (442) and (511)], and after implantation they exhibited a tendency to realign the crystallites along the even (hkl) planes [(222) and (442)]. On the Li+-implanted sample, one or more grains combine together and form bigger grains along with shallow pits, as observed through the atomic force micrographs. The as-deposited films have a percentage transmittance of 70-80% in the wavelength range 400-800 nm and the observed optical transmittance was less in Li+-implanted MgIn2O4 films. The index of refraction and the extinction co-efficient values were respectively n=1.98 and k=10-2 in the visible region. However, the DC electrical conductivity of Li+-implanted films to a fluence of 1015 ions/cm2 was nearly 0.7 S/cm at room temperature. The efficiency of the carrier generation was increased from 13.41% to 26.81% on annealing the implanted sample to lower fluence (1013 ions/cm2). [ABSTRACT FROM AUTHOR]

Abstract: Using a field emission gun based scanning electron microscopy, we report the formation of nanodots on the InP surfaces after bombardment by 100keV Ar+ ions under off-normal ion incidence (30° and 60° with respect to the surface normal) condition in the fluence range of 1×1016 to 1×1018 ionscm−2. Nanodots start forming after a threshold fluence of about 1×1017 ionscm−2. It is also seen that although the average dot diameter increases with fluence the average number of dots decreases with increasing fluence. Formation of such nanostructured features is attributed due to ion-beam sputtering. X-ray photoelectron spectroscopy analysis of the ion sputtered surface clearly shows In enrichment of the sputtered InP surface. The observation of growth of nanodots on the Ar+-ion sputtered InP surface under the present experimental condition matches well with the recent simulation results based on an atomistic model of sputter erosion. [Copyright &y& Elsevier]

Abstract: Thin films of magnesia (MgO) with (100) dominant orientations were implanted with 1.5MeV H+ ions at room temperature to various fluences of 1013, 1014 and 1015 ions/cm2. X-ray analysis unambiguously showed crystallinity even after a peak damage fluence of 1015 ions/cm2. Rutherford backscattering spectrometry combined with ion channeling (RBS/C) was used to analyze radiation damages and defect distributions. Optical absorption band observed at 5.7eV in implanted films was assigned to the anion vacancies and the defect was completely disappeared on annealing at 450°C. Number of F-type defects estimated was 9.42×1015 cm−2 for the film implanted with 1015 ions/cm2. DC electrical conductivity of 4.02×10−4 Scm−1 was observed in the implanted region which was three orders higher than the as-deposited films. In unison, film surface was modified as a result of the formation of aggregates caused by the atomic mixing of native matrix atoms (Mg and O) and precipitated hydrogen. [Copyright &y& Elsevier]

Abstract: In this paper, we present the changes occurring in Co/Pt bi- and multi-layer thin films modified under wide range of ion energy and species and fluence. We have shown the possibility of achieving controlled tuning of magnetic properties of the Co/Pt thin film system. Monte Carlo simulation results for ion-induced atomic displacements were used to explain the observed effects of ion-irradiation interface mixing across the Co/Pt interfaces. Phase formation has been explained in the light of heat of formation rule. On the other hand, we propose that ion induced point defect clustering governs the changes occurring in the structural and the magnetic properties. [Copyright &y& Elsevier]

Abstract: This paper reports on swift heavy ion beam induced epitaxial crystallization of a buried Si3N4 layer. Transmission electron microscopy and selected area diffraction patterns are used to study the epitaxial growth of the buried Si3N4 layer. We observe good epitaxial crystallization at 150°C and 200°C, respectively, for 70MeV Si and 100MeV Ag ions at an ion fluence of 1×1014 ionscm−2. The fact that recrystallization is achieved at a lower temperature for Si ions is attributed to the higher ratio (one order of magnitude) of the electronic to nuclear energy loss values compared to that of Ag ions. The possible role of the electronic and nuclear energy loss processes in the mechanism of recrystallization has also been discussed. [Copyright &y& Elsevier]

Abstract: We report on swift heavy ion beam induced epitaxial crystallization of a buried Si3N4 layer. High-resolution transmission electron microscopy and selected area diffraction patterns are used to study the 70MeV Si5+ ion beam induced epitaxial growth of the Si3N4 layer. We observe good epitaxial crystallization at 150°C, which is a much lower temperature as compared to the conventional solid phase epitaxial growth. A possible mechanism of recrystallization is discussed on the basis of formation of vacancies along the track of the swift heavy ion and their migration at elevated temperatures during irradiation. [Copyright &y& Elsevier]

Abstract: Based on the potential need of making nano-dimensional contact materials for successful miniaturization of nanoscale devices, we have attempted to synthesize nano-dimensional alloys on the surface of a material. This method has been termed as nanomixing. In this paper, we report on formation of nano-dimensional Au–Ge alloy islands by ion beam mixing of island thin films of Au and Ge. The nanoislands of Au and Ge were grown by UHV electron beam evaporation technique on Si(100) surface covered with a thin native oxide layer and were irradiated later on by different energetic ions (viz. 1.5MeV Au, 800keV Ar and 800keV Xe) at room temperature over a fluence range of 1×1014–2×1016 ionscm−2. We have carried out high-resolution transmission electron microscopic study to confirm the formation of Au–Ge alloy in the form of nanoislands. [Copyright &y& Elsevier]

Abstract: This paper focuses on the role of electronic energy loss in ion beam induced epitaxial crystallization for which swift heavy ions (100MeV Ag7+) have been used. We observed good epitaxial crystallization at 473–623K, which is a much lower temperature regime as compared to the one needed for conventional solid phase epitaxial growth. A systematic planar recrystallization has been observed as a function of temperature giving rise to an activation energy of 0.25±0.02eV. A possible mechanism of recrystallization is discussed on the basis of the production of vacancies along the track of the swift heavy ion and their migration at elevated temperatures. [Copyright &y& Elsevier]

Abstract: This paper shows the correlation of hydrogen content with the microstructure of a-C:H films. Samples having hydrogen content ranging from ∼3 to 40at% and varying microstructures have been prepared using the DC-glow discharge of acetylene (C2H2). Infrared absorption spectroscopy was employed primarily for extracting the bonding information, elastic recoil detection analysis was used to measure the total hydrogen concentration and mass spectroscopic thermal effusion was used for studying the thermal stability of the films. Ion-beam-induced release of hydrogen during elastic recoil detection analysis suggests that the kinetics of this release process is related to the total hydrogen content and microstructure of the samples. Significant differences in the mass spectroscopic thermal effusion spectra obtained from soft as well as hard films also reveal that effusion of various species is dependent on the film microstructure, which in turn is governed by the film growth parameters. [Copyright &y& Elsevier]

This paper reports on the formation of Ni2Ge alloy through interface modification of Ni/Ge bilayer structure using 100 MeV Au-ion irradiation at different temperatures and fluences. Compositional analysis and calculation of mixing efficiency were performed by Rutherford backscattering spectrometry. High resolution cross-sectional transmission electron microscopy was carried out for thickness determination and structure determination. Alloy formation has been discussed on the basis of swift heavy ion irradiation induced effects. [Copyright &y& Elsevier]

Formation of Au0.6Ge0.4 alloy on Si (1 0 0) substrate has been observed upon irradiating Au/Ge bilayer with 120 MeV Au ions and subsequent vacuum annealing at 360 °C. Transmission electron microscopy measurements on irradiated and vacuum annealed Au/Ge samples show a possibility of formation of oriented Au0.6Ge0.4 alloy, in agreement with X-ray diffraction data. These measurements reveal that although 120 MeV Au irradiation alone can not lead to a large scale mixing, it acts as a seed by forming nanoislands of Au0.6Ge0.4 alloy. Further post-irradiation annealing leads to vigorous intermixing of Au and Ge followed by the formation of large, closely packed and oriented Au0.6Ge0.4 islands. These results have been discussed on the basis of irradiation induced effects followed by subsequent thermal annealing. [Copyright &y& Elsevier]

Poly-crystalline Si film is an important material for its applications in microelectronics and solar cells. In order to realize poly-crystalline Si for practical application with high performance, it needs to be fabricated at room temperature. In this paper, we present a novel technique to develop poly-crystalline Si thin films at room temperature using 500 keV Xe+ ion irradiation. Here, the Al-induced crystallization process is employed to reduce the crystallization temperature. For that, c-Al (50 nm)/a-Si (150 nm) bilayer thin films have been used for ion irradiation experiments. Structural studies show that crystallization of Si starts at a threshold fluence of 3 × 1015 ions cm−2, and crystallinity is found to increase with increasing ion fluence. The results are explained in terms of displacement spike and thermal spike due to the interaction of energetic ions with target atoms. The transport of ions in matter Monte Carlo computer simulation code has been used to estimate the number of displacements due to ion irradiation. Generation of a sufficient amount of free Si atoms at threshold fluence and diffusion of these free Si atoms along the Al grain boundary starts the nucleation process. [ABSTRACT FROM AUTHOR]

We report room temperature delamination of chemically vapor deposited diamond films on a Si substrate due to 1.5 MeV He[sup +] ion bombardment. The delamination of films has been studied by scanning electron microscopy. The threshold fluence at which the delamination takes place has been determined in situ by monitoring the hydrogen signal with the help of elastic recoil detection analysis. Micro Raman measurements show the presence of residual stress (1.19 GPa) in the as-prepared films and its relaxation at the peripheri of the delaminated regions. It is proposed that enhancement of the residual stress during He[sup +] ion bombardment leads to stress saturation conditions which result in the delamination of the brittle diamond films from the film/substrate interface. These findings lead to the possibility of creating ion-beam induced channels in diamond films for device isolation by suitable choice of film/substrate combination. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Examines the room-temperature synthesis of copper germanide by ion beam mixing. Details on the resistivity of the mixed compounds; Information on the phase formation of the compounds; Information on the dominant moving species controlling phase formation; Explanation of the phase formation sequence.

The present study probes into the transition from anatase to rutile phase of TiO2 in 100 nm thick nanocrystalline thin films under thermal annealing and swift heavy ion (SHI) irradiation. The films were prepared using sol-gel and spin coating techniques on silicon (100) substrates. The as-deposited films are found to be amorphous by glancing angle x-ray diffraction and Raman spectroscopy. Though thermal annealing is known to cause transformation from anatase to rutile phase of TiO2 in a temperature interval of 700–900 °C, in nanoparticle thin films, we found that a sizable volume fraction of anatase still remains even after annealing at 1000 °C. Irradiations by 200 MeV Ag ions on the other hand suppressed the anatase phase and almost phase pure rutile TiO2 could be obtained at a fluence of 3×1012 ions cm-2. A mechanism based on the competing effect of grain growth and conversion of anatase to rutile at the grain boundary of the anatase on annealing and conversion of anatase to rutile in the grains of the anatase due to SHI induced thermal spike is proposed to explain the observed result. [ABSTRACT FROM AUTHOR]

Megaelectron volts ion-induced effects for discontinuous gold nanoislands and for continuous gold films on silicon substrate have been studied. Irradiation was carried out with 1.5 MeV Au2+ ions at room temperature to various fluences. Cross-sectional transmission electron microscopy and Rutherford backscattering spectrometry are used to study the ion-beam mixing in Au/Si systems. At a fluence of 1×1014 ions cm-2, a material push-in effect and a metastable Au-Si phase formation have been observed for Au nanoislands, while no push in or mixing has been observed for the case of continuous films. The mixed phase of Au-Si system is found to be crystalline in nature. The material push- in and ion-beam mixing effects that are observed in case of nanoislands appear to be due to combined effect of capillary driving force, ion-induced viscous flow, and ion-induced energy spike effects. [ABSTRACT FROM AUTHOR]

Crystalline Si films incorporated with Al are important for applications in microelectronics and solar cells. In this paper, we report on the morphology of crystalline Si surfaces in Al/amorphous-Si bilayer thin films under ion beam irradiation at 100 °C. Micro-Raman and transmission electron microscopy studies show that best crystallization is achieved at a fluence of 1 × 1012 ions cm−2. The contact angle of Si surfaces (after chemically etched unreacted Al), referred to as absorber surfaces, decreases with increasing ion fluence. These surfaces are hydrophobic in nature and the hydrophobicity decreases with increasing ion fluence. Fractal and multifractal analysis of atomic force microscopy images, along with system energy/unit cell and Laplace pressure calculations, supports our observations. Moreover, the calculated multiple scattering cross sections of light, along with reflectivity measurements, indicate that absorber surfaces of best crystalline films have the lowest reflectivity. The present results suggest that such surfaces having low optical reflectance and a hydrophobic nature can be used as photon absorber layers for advanced solar cell devices. [ABSTRACT FROM AUTHOR]

In this paper we establish certain multivalued fixed point results for mappings satisfying rational type almost contractions involving a control function in the framework of metric spaces. The main result is supported with an example. We use the Hausdorff distance in our theorems. We also study the stability of fixed point sets of the above mentioned set valued contractions. [ABSTRACT FROM AUTHOR]

In this article, the approximate solutions of the non-linear Drinfeld-Sokolov-Wilson equation with fractional time derivative have been obtained. The fractional derivative is described in the Caputo sense. He's polynomial is used to tackle the nonlinearity which arise in our considered problems. A time fractional nonlinear partial differential equation has been computed numerically. The numerical procedures illustrate the effectiveness and reliability of the method. Effects of fractional order time derivatives on the solutions for different particular cases are presented through graphs. [ABSTRACT FROM AUTHOR]

In real-world data deluge, due to insignificant information and high dimension, irrelevant and redundant attributes reduce the ability of experts both in predictive accuracy and speed, respectively. Attribute selection is the notion of selecting those attributes that are essential as well as enough to specify the target knowledge preferably. Fuzzy rough set-based approaches play a crucial role in selecting relevant and less redundant attributes from a high-dimensional dataset. Intuitionistic fuzzy set-based approaches can handle uncertainty as it gives an additional degree of freedom when compared to fuzzy approaches. So, it has a more flexible and practical ability to deal with vagueness and noise available in the information system. In this paper, we introduce two new robust approaches for attribute selection based on intuitionistic fuzzy rough set theory using the concepts of Different Classes ratio and Laplace Summation operator. Firstly, Different Classes ratio and Laplace Summation operator based lower and upper approximations are established based on intuitionistic fuzzy rough set concept. Moreover, we present algorithms and illustrative examples for a better understanding of our approaches. Finally, experimental analysis is performed on some real-valued datasets for attribute selection and classification accuracies. [ABSTRACT FROM AUTHOR]

Abstract: In this paper evolution of silicon surface topography, under low energy ion bombardment, is investigated at higher oblique incident angles in the range of 63–83°. Si(100) substrates were exposed to 500eV argon ions. Different surface morphologies evolve with increasing angle of incidence. Parallel-mode ripples are observed up to 67° which undergo a transition to perpendicular-mode ripples at 80°. However, this transition is not a sharp one since it undergoes a series of unusual pattern formation at intermediate angles. For instance, mounds, cone-, and needle-like structures appear at intermediate angles, viz. in the angular range of 70–78°. Complete smoothening of the silicon surface is observed at incident angles beyond 80°. The observed patterns are attributed to surface confined viscous flow and sputter erosion under ion bombardment. [Copyright &y& Elsevier]

Modification of the surface morphologies of titanium oxide nanoparticle thin films under swift heavy ion (SHI) irradiation was investigated using glancing angle X-ray diffractometry and atomic force microscopy. Irradiation at low ion fluences leads to grain fragmentation and a narrowing of the grain size distribution, whereas grain growth with increased average grain size and grain size distribution occur at high fluences. Associated with the change in the grain size and size distribution there occurs topological modifications at different fluences of SHI irradiation. The SHI-induced grain fragmentation, grain growth and modification of surface topography are explained by the thermal spike model of ion-matter interaction. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on the change in the magnetic and the structural properties of Pt/Cr/Co multilayers due to 1 MeV N+-ion irradiation at room temperature. We observe irradiation induced formation of the CoCrPt ternary alloy phase at a fluence of 1×1016 ions cm−2. Phase formation is accompanied by an enhancement in the coercivity. The enhancement in the coercivity is attributed to inhomogeneous alloying and possible mixing-induced strain. These findings are explained in the light of ion beam induced recoil mixing and ionization events. [Copyright &y& Elsevier]

MeV ion induced mixing in the nanoscale regime for Au and Ag nanoislands on silicon substrates has been studied. Au and Ag nanoislands are grown on silicon substrates at room temperature and irradiated with 1.5-MeV Au2+ ions at various fluences. Cross-sectional high-resolution transmission electron microscopy and Rutherford backscattering spectrometry (RBS) are used to study the ion-beam mixing in Au/SiOx/Si and Ag/SiOx/Si systems. We observe a metastable mixed phase for the Au–Si system at a fluence of 1×1014 ions cm-2, while no mixed phase is formed for the Ag–Si system. For both Au–Si and Ag–Si systems, a part of the islands is pushed into the substrate. The mixed phase of the Au–Si system is found to be crystalline in nature. The higher eutectic temperature and lower heat of mixing of the Ag–Si system compared to the Au–Si system could be responsible for the lack of mixing and silicide formation in the Ag–Si system. [ABSTRACT FROM AUTHOR]

In order to understand electronic sputtering phenomenon, a systematic study is performed by bombarding fullerene (C60) thin films deposited on Si and glass substrates with Au and Ag ions of different energies. The incident ion velocity, charge state and substrate dependent electronic sputtering yield (sputtered atoms/ion) of C is measured on-line by elastic recoil detection analysis (ERDA) technique in the three different sets of studies. The salient features observed in these experiments are that the yield is quite high (∼103 atoms/ion and above), which is influenced by the above-mentioned three physical parameters. Slower ion having same electronic energy deposition (Se) as compared to its high velocity counterpart erodes more. C60 films deposited on more insulating substrate (electrically and thermally: glass) shows higher sputtering yield as compared to those deposited on Si substrate. However, no charge state effect was observed in the electronic sputtering yield within the detection limit of the set up. [Copyright &y& Elsevier]

Electronic sputtering of a-C:H films by elastic recoil detection analysis technique is studied under 80 MeV Ni8+ and 150 MeV Ag13+ ion irradiations. These studies show that electronic sputtering yield of C and H from the films varies with film structure quite significantly. The structure of the films is analyzed from the characteristic graphitic (G) and disordered (D) modes of Raman vibration. Atomic force microscopy was performed on two films for grain size determination. The difference in electronic sputtering yields is discussed on the basis of structural influence of the films on swift heavy ion and solid interaction. [Copyright &y& Elsevier]

Post-deposition annealing mediated evolution of self-decorated Au nanoparticles (NPs) on chemically etched Si pyramids is presented. A distinct transformation of Si surfaces from hydrophilic to hydrophobic is initially found after chemical texturing, showing an increase in contact angle (CA) from 58° to 98° (±1°). Further improvement of hydrophobicity with CA up to ~118° has been established after annealing a 10 nm thick Au-coated Si pyramids at 400 °C that led to the formation of Au NPs on Si facets along with self-ordering at the pyramid edges. Detailed x-ray diffraction studies suggest the evolution of crystalline Au NPs on strained Si facets. Microstructural studies, however, indicate no mixing of Au and Si atoms at the Au/Si interfaces, instead of forming Au nanocrystals at 400 °C. The improved hydrophobicity of Si pyramids, even with Au NPs can be explained in the light of a decrease in solid fractional surface area according to Wenzel's model. Moreover, a sharp drop in specular reflectance from Si pyramids in the range of 300-800 nm, especially in the ultraviolet region up to ~0.4% is recorded in the presence of Au NPs by ultraviolet-visible spectroscopy, reflecting the possible use in photovoltaic devices with improved antireflection property. [ABSTRACT FROM AUTHOR]

Sputter deposited Al doped ZnO (AZO) thin films exhibit a dual hydrogen sensing response in the temperature range 40 °C-150 °C after surface modifications with palladium nanoparticles. The unmodified AZO films showed no response in hydrogen in the temperature range 40 °C-150 °C. The operational temperature windows on the low and high temperature sides have been estimated by isolating the semiconductor-to-metal transition temperature zone of the sensor device. The gas response pattern was modeled by considering various adsorption isotherms, which revealed the dominance of heterogeneous adsorption characteristics. The Arrhenius adsorption barrier showed dual variation with change in hydrogen gas concentration on either side of the semiconductor-to-metal transition. A detailed analysis of the hydrogen gas response pattern by considering the changes in nano palladium due to hydrogen adsorption, and semiconductor-to-metal transition of nanocrystalline Al doped ZnO layer due to temperature, along with material characterization studies by glancing incidence X-ray diffraction, atomic force microscopy, and transmission electron microscopy, are presented. [ABSTRACT FROM AUTHOR]

Al-doped ZnO (AZO) thin films of thicknesses 5,10, 15, 20, and 30 nm were deposited on 500 eV argon ion-beam fabricated nanoscale self-organized rippled-Si substrates at room temperature and are compared with similar films deposited on pristine-Si substrates (without ripples). It is observed that morphology of self-organized AZO films is driven by the underlying substrate morphology. For instance, for pristine-Si substrates, a granular morphology evolves for all AZO films. On the other hand, for rippled-Si substrates, morphologies having chain-like arrangement (anisotropic in nature) are observed up to a thickness of 20 nm, while a granular morphology evolves (isotropic in nature) for 30 nm-thick film. Photoluminescence studies reveal that excitonic peaks corresponding to 5-15 nm-thick AZO films, grown on rippled-Si templates, show a blue shift of 8 nm and 3 nm, respectively, whereas the peak shift is negligible for 20-nm thick film (with respect to their pristine counter parts). The observed blue shifts are substantiated by diffuse reflectance study and attributed to quantum confinement effect, associated with the size of the AZO grains and their spatial arrangements driven by the anisotropic morphology of underlying rippled-Si templates. The present findings will be useful for making tunable AZO-based light-emitting devices. [ABSTRACT FROM AUTHOR]

Room temperature irradiation of InSb(111) by 60 keV Ar+-ions at normal (0°) and oblique (60°) angles of incidence led to the formation of nanoporous structure in the high fluence regime of 1 x 1017 to 3 x 1018 ions cm-2 . While a porous layer comprising of a network of interconnected nanofibers was generated by normal ion incidence, evolution of plate-like structures was observed for obliquely incident ions. Systematic studies of composition and structure using energy dispersive x-ray spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Raman mapping, grazing incidence x-ray diffraction, and cross-sectional transmission electron microscopy revealed a high degree of oxidation of the ion-induced microstructures with the presence of In2O3 and Sb2O3 phases and presence of nanocrystallites within the nanoporous structures. The observed structural evolution was understood in terms of processes driven by ion-induced defect accumulation within InSb. [ABSTRACT FROM AUTHOR]

In this paper, a fluence-dependent antireflection performance is presented from ion-beam fabricated nanofaceted-Si surfaces. It is also demonstrated that these nanofacets are capable of producing room temperature ultra-violet and blue photoluminescence which can be attributed to inter-band transitions of the localized excitonic states of different Si-O bonds at the Si/SiOx interface. Timeresolved photoluminescence measurements further confirm defect-induced radiative emission from the surface of silicon nanofacets. It is observed that the spectral characteristics remain unchanged, except an enhancement in the photoluminescence intensity with increasing ion-fluence. The increase in photoluminescence intensity by orders of magnitude stronger than that of a planar Si substrate is due to higher absorption of incident photons by nanofaceted structures. [ABSTRACT FROM AUTHOR]

Room temperature implantation of 60 keV Ar+-ions in GaSb to the fluences of 7×1016 to 3×1018 ions cm-2 is carried out at two incidence angles, viz 0° and 60°, leading to formation of a nanoporous layer. As the ion fluence increases, patches grow on the porous layer under normal ion implantation, whereas the porous layer gradually becomes embedded under a rough top surface for oblique incidence of ions. Grazing incidence x-ray diffraction and cross-sectional transmission electron microscopy studies reveal the existence of nanocrystallites embedded in the ion-beam amorphized GaSb matrix up to the highest fluence used in our experiment. Oxidation of the nanoporous layers becomes obvious from x-ray photoelectron spectroscopy and Raman mapping. The correlation of ion-beam induced structural modification with photoluminescence signals in the infrared region has further been studied, showing defect induced emission of additional peaks near the band edge of GaSb. [ABSTRACT FROM AUTHOR]

Room temperature irradiation of GaSb by 60 keV Ar+-ions at an oblique incidence of 60° leads to simultaneous formation of a nanoporous layer and undulations at the interface with the underlying substrate. Interestingly, with increasing ion fluence, a gradual embedding of the dense nanoporous layer takes place below ridge-like structures (up to the fluence of 1×1017 ions cm–2), which get extended to form a continuous layer (at fluences ≥4×1017 ions cm–2). Systematic compositional analyses reveal the co-existence of Ga2O3 and Sb2O3 in the surface layer. The results are discussed in terms of a competition between ion-induced defect accumulation and re-deposition of sputtered atoms on the surface. [ABSTRACT FROM AUTHOR]

Abstract: We report on CoCrPt ternary alloy phase formation and changes in magnetic properties of Co/Cr/Pt multilayers due to 1 MeV N+ ion irradiation at room temperature. Irradiation induced changes occurring across the Co/Cr/Pt interfaces are studied by X-ray reflectivity, glancing angle X-ray diffraction, and magneto optical Kerr effect measurements. Irradiation induced mixing across the interface shows an enhancement in the coercivity, sufficient coercivity squareness and magnetic anisotropy. The results are discussed in the realm of ion beam induced recoil mixing across the interfaces. [Copyright &y& Elsevier]

Abstract: GaAs(100) samples were exposed to 1.5 MeV Au2+ ions at room temperature. Changes in the surface morphology and the structural properties of ion irradiated GaAs samples were studied as a function of ion fluence in the range of 1×1014–1×1015 ions cm−2 at an incident angle of 75°. The samples were investigated by atomic force microscopy and micro-Raman spectroscopy. We observe the formation of nanodots on the irradiated surfaces. The room-temperature micro-Raman investigation of these nanostructures reveals optical phonon softening due to phonon confinement in the surface nanostructures. The observed features are discussed in the framework of ion-matter interaction in the MeV regime. [Copyright &y& Elsevier]

Herein, the structural, optical, and electrical properties of Au-induced crystallization in amorphous germanium (a-Ge) thin films are presented for future solar energy material applications. The a-Ge/Au thin films on quartz substrate were prepared via the e-beam and thermal evaporation techniques, respectively. The as-prepared samples were irradiated with 100 MeV Ni7+ ions at different fluences of 1 × 1012 ions per cm2, 5 × 1012 ions per cm2, 1 × 1013 ions per cm2 and 5 × 1013 ions per cm2. The ion irradiation did not result in the crystallization of Ge; instead, an increase in ion fluence decreased the Au crystallite size, which ultimately deteriorated the Au crystallization. The ion-irradiated samples were post-annealed for 4 h at a fixed temperature of 300 °C to achieve the crystallization of Ge. The post-annealing of the ion-irradiated samples led to the crystallization of Ge, where the crystallization of Ge was better for the samples irradiated at high fluence, leading to a smaller grain size corresponding to a high grain boundary, and hence high defect sink density. The energy bandgap of crystalline Ge was determined using reflectance and transmittance spectra, which was found to be low (∼0.64 eV) at higher fluence. The field-emission scanning electron microscopy and atomic force microscopy analyses show that the surface microstructure changed for the post-annealed samples irradiated at different fluences. The role of the fractal-like surface microstructure in multiple scattering of light on the film surface is discussed. Thus, the lower values of resistivity and sheet resistance as well as good optical properties of Ge make it a promising material for future poly-Ge-based solar cell applications. [ABSTRACT FROM AUTHOR]

Many iterative algorithms like Picard, Mann, Ishikawa are very useful to solve fixed point problems of nonlinear operators in real Hilbert spaces. The recent trend is to enhance their convergence rate abruptly by using inertial terms. The purpose of this paper is to investigate a new inertial iterative algorithm for finding the fixed points of nonexpansive operators in the framework of Hilbert spaces. We study the weak convergence of the proposed algorithm under mild assumptions. We apply our algorithm to design a new accelerated proximal gradient method. This new proximal gradient technique is applied to regression problems. Numerical experiments have been conducted for regression problems with several publicly available high-dimensional datasets and compare the proposed algorithm with already existing algorithms on the basis of their performance for accuracy and objective function values. Results show that the performance of our proposed algorithm overreaches the other algorithms, while keeping the iteration parameters unchanged. [ABSTRACT FROM AUTHOR]

This paper reports on structural, optical, vibrational, and morphological properties of cobalt-doped CdS thin films, prepared by 90 keV Co+ implantation at room temperature. In this work, we have used cobalt concentration in the range of 0.34–10.8 at. %. Cobalt doping does not lead to the formation of any secondary phase, either in the form of metallic clusters or impurity complexes. However, with increasing cobalt concentration a decrease in the optical band gap, from 2.39 to 2.26 eV, is observed. This reduction is addressed on the basis of band tailing due to the creation of localized energy states in association with Urbach energy calculations. In addition, implantation gives rise to grain growth and increase in the surface roughness. Size and shape fluctuations of individual CdS grains, at higher fluences, give rise to inhomogeneity in strain. The results are discussed in the light of ion-matter interaction in the keV regime. [ABSTRACT FROM AUTHOR]