Ion beam induced modifications in electron beam evaporated aluminum oxide thin films

Al2O3 thin films find wide applications in optoelectronics, sensors, tribology etc. In the present work, Al2O3 films prepared by electron beam evaporation technique are irradiated with 100 MeV swift Si7+ ions for the fluence in the range 1 × 1012 to 1 × 1013 ions cm−2 and the structural properties are studied by glancing angle X-ray diffraction. It shows a single diffraction peak at 38.2° which indicates the γ-phase of Al2O3. Further, it is observed that as the fluence increases up to 1 × 1013 ions cm−2 the diffraction peak intensity decreases indicating amorphization. Surface morphology studies by atomic force microscopy show mean surface roughness of 34.73 nm and it decreases with increase in ion fluence. A strong photoluminescence (PL) emission with peak at 442 nm along with shoulder at 420 nm is observed when the samples are excited with 326 nm light. The PL emission is found to increase with increase in ion fluence and the results are discussed in detail

Synthesis and Characterization of Gold Nanorings

International audienceIn the present work, we report the formation of Au nanorings on quartz substrate by thermal evaporation of Au on quartz and subsequent annealing in certain conditions as a function of metal volume fraction and annealing temperature. Optical extinction cross-sections measurements and atomic force microscopy (AFM) studies have been performed on the as-deposited and annealed samples. No signature of nanoparticles formation is found in case of as-deposited samples, while spectra of annealed samples show a clear signature of surface plasmon resonance absorption (SPR) peaks around 580 nm, which reveals the formation of Au nanostructure. AFM images clearly show the formation of Au nanorings under certain conditions. The observed SPR frequency of the Au nanorings in our case is in agreement with the estimated frequency obtained from the formulation of Aizpurua et al. Optical extinction measurements at different incidence angles were performed, which showed splitting of SPR at angles beyond 20°

AFM and photoluminescence studies of swift heavy ion induced nanostructured aluminum oxide thin films

E-beam evaporated aluminum oxide films were irradiated with 120 MeV swift Au9+ ions in order to induced nanostructure formation. Atomic force microscope (AFM) results showed the formation of nanostructures for films irradiated with a fluence of 1 à 1013 ions cm-2. The particle size estimated by section analysis of the irradiated film was in the range 25-30 nm. Glancing angle X-ray diffraction (GAXRD) revealed the amorphous nature of the films. Two strong Photoluminescence (PL) emission bands with peaks at â¼430 nm and â¼645 nm besides a shoulder at â¼540 nm were observed in all irradiated samples. The PL intensity is found to increase with increase of ion fluence. © 2008 Elsevier B.V. All rights reserved

Magnetic Force Microscopy of Nano-Size Magnetic Domain Ordering in Heavy Ion Irradiated Fullerene Films

International audienceIn the present work, magnetic force microscopy is employed to investigate the magnetic ordering in ion irradiated fullerene films. It is observed that magnetic domain size is ∼100-200 nm and magnetic signal is stronger at the domain boundaries. Magnetic signal arise in irradiated films is confirmed by magnetic measurements using a superconducting quantum interference device which increases with the ion fluence. The induced magnetism is possibly due to structural defects in the amorphous carbon phase formed by ion irradiation

Thermal annealing induced competition of oxidation and grain growth in nickel thin films

The interface of Ni-NiO thin films was developed by thermal evaporation of nickel and subsequent annealing in oxygen atmosphere at 400 °C at varying duration of time. The evolution of layer thicknesses with annealing time was studied using rutherford backscattering spectrometry. The structural characterization showed grain growth stagnation for Ni at higher duration of annealing. The Ni phase had more crystallinity compared to the NiO phase. The surface was studied using atomic force microscope. The magnetic domains were also imaged. Magnetic stripe domain patterns were observed for selected films. Variation in saturation magnetisation and coercivity with annealing time was observed. The observation of weak exchange bias shows the importance of antiferromagnetic phase in determining the exchange bias properties. Thermal annealing of Ni films caused a competition among oxidation and grain growth

Swift heavy ion induced structural modification of atom beam sputtered ZnO thin film

International audienceIn the present study, we have investigated the swift heavy ion induced structural modification of ZnO thin film deposited by atom beam sputtering. The films were irradiated by 100 MeV Ag ions at different fluences from 5 x 10(10) ions/cm(2) to 3 x 10(13) ions/cm(2). The influence of the irradiation fluence on structural and optical properties of these thin films was investigated. The structural properties have been studied using X-ray diffraction. The Zn-O bonding was confirmed by Fourier transform infrared spectroscopy and surface morphology was investigated by atomic force microscopy. XRD confirmed that the grain size and texture of the ZnO thin film are increased after the irradiation. The absorption peak intensity corresponding to Zn-O bonding is also increased as a result of energy deposition by swift heavy ion as revealed by FTIR. The AFM study of the films implied that roughness remains almost constant. Power spectral density was also estimated from the AFM micrograph to extract the value of roughness exponent. (C) 2009 Elsevier B.V. All rights reserved