D.K. Avasthi

University of Petroleum and Energy Studies

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Saif Khan

University of Ha'il

A. P. Pathak

University of Hyderabad

D. Kabiraj

Inter-University Accelerator Centre

S. Dhamodaran

Sathyabama Institute of Science and Technology

Satyabrata Mohapatra

Indian Institute of Science Education and Research, Tirupati

D. C. Agarwal

Inter-University Accelerator Centre

Udai B. Singh

Deen Dayal Upadhyaya Gorakhpur University

Yogendra Kumar Mishra

University of Southern Denmark

A. Tripathi

Inter-University Accelerator Centre

Fouran Singh

Inter-University Accelerator Centre

Cooperative Institutions

Inter-University Accelerator Centre

Indian Institute of Technology Delhi

Institute of Physics, Bhubaneshwar

UGC DAE Consortium for Scientific Research

University of Hyderabad

Bhabha Atomic Research Centre

Homi Bhabha National Institute

Banaras Hindu University

University of Delhi

University of Petroleum and Energy Studies

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Single Layer Nanocrystalline Silicide Synthesis from Zr/Si Multilayers

Transactions of the Materials Research Society of Japan (2011)

D. Bhattacharya G. Prìncìpí Ajay Gupta D.K. Avasthi

Swift heavy ion (SHI) beam (120 MeV Au, 1013 ions/cm2) irradiation of Zr/Si multilayers, deposited on Si substrates at room temperature, resulted in complete mixing of the structure, transforming it directly into a single layer of purely crystalline ZrSi2 (C49 type structure) on the substrate. As-deposited and SHI irradiated samples were analyzed by specular x-ray reflectivity and grazing incidence x-ray diffraction. The generation of this refractory silicide, known to be vital to integrated device processing, directly on Si and without annealing is a technologically useful result. Dynamics of the process was attributed to electron-phonon energy transfer and interdiffusion at the interface during transient melt phase, through application of thermal spike model. Within the framework of this model, the present work establishes an experimentally observed threshold for electronic excitation (Se) of Zr (24.4 keV/nm), leading to mixing in the Zr/Si system. However, this value is lower than the reported threshold for defect/track creation by electronic energy loss in Zr (28 keV/nm). Since it is known that SHI induced mixing takes place across the interface when Se exceeds this threshold, the results obtained through this study signify in effect, the greater sensitivity of Zr to swift heavy ion induced radiation damage.

Swift heavy ion

Nanocrystalline material

Ion beam mixing

10.14723/tmrsj.36.129

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Quantification of the mixing effect in silicon–manganese thin films by swift heavy ion irradiation

Journal of Physics D Applied Physics (2008)

K. Diva B.R. Chakraborty R.S. Chauhan J.C. Pivin D.K. Avasthi

Swift heavy ion induced mixing is reported in a-Si/Mn/a-Si thin films on a silicon wafer, when irradiated by 120 MeV Au ions at three different fluences of 1 × 1013, 3 × 1013 and 1 × 1014 ions cm−2. The samples were characterized before (pristine) and after irradiation using secondary ion mass spectroscopy (SIMS) and Rutherford backscattering spectroscopy (RBS). Atomic force microscopy of the samples was used to determine the surface roughness contribution to RBS and SIMS profiles. Depth profiles showed distinct changes in the interface region and it was observed that interface mixing increased linearly with the increase in the ion fluence. The mixing rate was estimated to be ∼1000 nm4. The mixing effect is explained in the framework of the thermal spike model. The track radius and duration of the transient melt phase have been theoretically calculated for this system to estimate the diffusivity during the transient melt stage at the interface.

Swift heavy ion

Swift

10.1088/0022-3727/41/18/185305

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Low- and high-energy irradiations of InGaAs/GaAs heterostructures: a comparison

Radiation effects and defects in solids (2007)

S. Dhamodaran A. P. Pathak D.K. Avasthi R. Muralidharan G. Sai Saravanan

The effects of ion irradiation on InGaAs/GaAs heterostructures have been studied using Raman spectroscopy. The structures consist of molecular beam epitaxy grown InGaAs layers on GaAs(0 0 1), having layer thicknesses of 12, 36, 60 and 96 nm. For irradiation, 3 MeV Ag2+ and 150 MeV Ag12+ have been used at 1×1015 and 1×1013 ions/cm2 fluences, respectively. We refer to 3 and 150 MeV irradiations as low- and high-energy irradiations, respectively. The low-energy irradiation damaged the lattice heavily and no phonon modes were observed in the as-irradiated samples. The samples were then subjected to rapid thermal annealing (RTA) to recover the phonon modes. Though the phonon modes were observed after RTA, the GaAs-type TO mode is more intense than the LO mode indicating residual defects. The TO mode position is found to be the same in all the annealed samples, whereas the LO phonon mode positions do not follow any trend in the low-energy irradiated samples. In contrast, no post-annealing was performed in high-energy irradiated samples. An intense GaAs-type LO mode was observed comparable with the as-grown ones, indicating no loss of crystalline quality. The TO mode intensity was found to decrease after irradiation. After high-energy irradiation, the GaAs-type longitudinal optical (LO) mode blueshifted in thin samples and redshifted in thick samples when compared with as-grown samples. Raman spectra of thin samples indicate a compressive strain developing in the substrate, close to the interface upon irradiation. This along with inter-diffusion is expected to be the reason for the observed modifications. The variations in FWHM of the Raman modes are discussed in detail. The results are discussed invoking the penetration depth of the probe radiation (λ=514.5 nm) in InGaAs. We have demonstrated that the high-energy irradiation is useful to modify the material property without the loss of crystalline quality and does not need post-annealing. Atomic force microscopy has also been employed for surface analysis.

10.1080/10420150601133279

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Ion beam analysis

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms (2008)

A. P. Pathak D.K. Avasthi B. N. Dev

Ion beam analysis

10.1016/j.nimb.2008.03.093

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Ion Beam Synthesis of SERS Substrate

2022 International Conference on Electrical Engineering and Photonics (EExPolytech) (2021)

Akanksha Motla Sumaya Nisar Vikas Baranwal Kavita Sharma B. Sundarawel

Surface Enhanced Raman Spectroscopy (SERS) is a powerful tool to amplify weak Raman signals by an increment of the apparent Raman cross-section of the analytes. The present work reports on ion beam synthesized SERS substrates. Thin films of Au were deposited on quartz substrate using ion beam sputtering. The films were further irradiated by 1.36 MeV Xe ions to a fluence of 10 ¹⁵ and 10 ¹⁶ ion/cm ² . Rutherford Backscattering (RBS) was performed for Au thin film deposited on quartz to evaluate the Au content. Thickness of the film was found to be -- 7.8nm by RBS. The FESEM was performed for pristine and irradiated samples which revealed the formation of separated distinguishable Au nanoparticles in irradiated samples. The UV-Visible spectroscopy was carried out for pristine and irradiated materials which indicated surface plasmon resonance due to the formation of Au nanoparticles after ion irradiation. The assessment of SERS was performed on High Resolution Raman using 10 ⁻⁴ M di-nitro salicylic acid (DNSA) as a model analyte, which has a similar chemical structure to the commonly found explosives. The presence of NO 2 group and aromatic ring stretching vibration were observed on the irradiated sample which were otherwise not observed on the pristine sample. Hence, this demonstrated ion beam synthesis of SERS substrate.

Rutherford backscattering spectrometry

Surface-Enhanced Raman Spectroscopy

10.1109/eexpolytech53083.2021.9614915

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Formation of TiO-single crystals in Ag-TiO2 based nanocomposites by swift heavy ion irradiation

Venkata Sai Kiran Chakravadhanula Yogendra Kumar Mishra Venkata Girish Kotnur Tomislav Hrkac Lorenz Kienle

In present work, we report the synthesis of Ag-TiO ₂ nanocomposite thin films and their modification by swift heavy ions (SHI). Co-sputtering of silver together with titanium oxide (TiO ₂ ) was used to produce Ag-TiO ₂ nanocomposite coatings, where Ag nanoparticles are embedded in TiO ₂ matrix. The Ag-TiO ₂ nanocomposite films (thickness ~35nm) with silver-volume-fraction between 10 and 40 % were prepared by co-sputtering of Ag and TiO ₂ using two different sources. Microstructural, optical and antibacterial properties of nanocomposite films were studied. Swift heavy ions were used to engineer different properties of nanocomposites.

10.1109/cleoe-eqec.2009.5192300

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Swift heavy ion induced mixing in metal/metal system

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms (2006)

Sarvesh Kumar R.S. Chauhan Saif Khan W. Bolse D.K. Avasthi

Ion beam mixing

Stopping power

Swift heavy ion

Liquid nitrogen

Ion track

10.1016/j.nimb.2005.11.054

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Study of thermal annealing induced plasmonic bleaching in Ag:TiO2 nanocomposite thin films

Scripta Materialia (2015)

Manish Kumar Tanuj Kumar D.K. Avasthi

Rutherford backscattering spectrometry

Nanomaterials

Thermal Treatment

10.1016/j.scriptamat.2015.04.030

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Citations (32)

Electrical and Thermal Studies on the Polyvinylchloride/Carbon Black Composites Induced by High Energy Ion Beam

Integrated ferroelectrics (2010)

Dolly Singh N. L. Singh Anjum Qureshi Chaitali Gavade D.K. Avasthi

Modification induced by energetic ion in polyvinylchloride (PVC)/carbon black (CB) composites was studied using impedance gain-phase analyzer, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Different concentrations of CB were dispersed in PVC films. These films were irradiated with 140 MeV Ag11+ ions at the fluences of 1 × 1011 and 1 × 1012ions/cm2. The ac electrical conductivity and dielectric response were studied as a function of filler, frequency and ion fluence. It was found that ac electrical conductivity increases with increasing the percentage of CB, frequency and ion fluence. The observed enhancement in ac electrical conductivity is attributed to the increase in the number of conduction paths created by the carbon black contents in the composites to give a higher electrical conductivity. An increase in dielectric constant was observed with the ion fluence and also with the carbon black content, which is attributed to the interfacial polarization of heterogeneous systems. Differential scanning calorimetry (DSC) analysis showed that the glass transition temperature (Tg) shifted towards lower temperature with increasing the ion fluence. It may be attributed to the scissioning of polymer chains and as a result increase of free radicals, unsaturation etc., which lead to the transformation of polymer into amorphous phase. Atomic force microscopy (AFM) studies revealed that the surface average roughness of the composites increases as filler concentration increases and decreases upon irradiation. SEM micrographs showed that carbon black particles organized into aggregates of micro spherical voids and decreased its size upon irradiation.

10.1080/10584587.2010.489429

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Swift heavy ion irradiated InGaAs/InP multi quantum wells: Band-structure, interface and surface modifications

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms (2007)

S. Dhamodaran A. P. Pathak A. Turos G. Sai Saravanan Saif Khan

Swift heavy ion

10.1016/j.nimb.2007.11.073

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Citations (5)