Influence Of Ion Beam Irradiation Research Articles

Influence of Ion Beam Irradiation on Optical and Magnetic Properties of Transparent Mn Doped ZnO Thin Films, Suitable for Sensor Applications

The present work describes modification in physical properties of Zn0.95Mn0.05O films by ion beam irradiation. Films were prepared by spin coating and annealed at 500 °C. XRD patterns of these films show wurzite structure with good crystalline quality. However, Low energy irradiation could modify and induces new defect states. Characterization of those defects had been performed by analysing the UV-Visible absorption spectroscopy and Photoluminescence (PL) spectroscopy. Room temperature PL emission of Zn0.95Mn0.05O film shows a broad UV emission and pronounced visible emission ∼530 nm. At low temperature broad UV band become more prominent however it is completely quenched after irradiation. For all irradiated films we had notice only visible emission of comparable intensities, confined within the region 475 nm to 550 nm. Irradiated films are showing ferromagnetism at room temperature and most importantly the film irradiated at fluence F: 1016 ions cm−2 exhibit maximum saturation magnetic moment of 0.83 emu g−1. The magnetic response is strongly influenced by irradiation and we could say that magnetism is strongly correlated with intrinsic defects present in these films. Defect induced formation of bound magnetic polarons (BMP) actually control the ferromagnetic property of these films. These transparent ferromagnetic films could be used in optoelectronics.

Influence of ion beam irradiation induced defects on the structural, optical and electrical properties of tellurium nanowires

In this study, tellurium nanowires were electrodeposited into the polymer membranes from aqueous acidic bath containing HTeO2+ ions. The field emission scanning electron microscopy (FESEM) images confirmed the formation of uniform and straight nanowires. The influence of 110 MeV Ni8+ ion irradiation induced defects on the structural, optical and electrical properties of as–deposited tellurium nanowires were examined using X-ray diffraction (XRD), UV–visible absorption spectroscopy and current–voltage (I–V) measurements. The XRD data depicted the hexagonal phase of tellurium nanowires and further revealed a variation in the intensity of diffraction peaks of ion irradiated nanowires. Williamson–Hall (WH) analysis is used for convoluting the size and microstrain contributions to the width of diffraction peaks. Tellurium nanowires exhibited a distinct absorbance band in the visible region at 686 nm, while this was absent in bulk tellurium. Electrical properties of nanowires are explored on the basis of I–V curves, which revealed a significant increase in the electrical conductivity of irradiated nanowires. A possible mechanism for the enhanced electrical conductivity is the increase in carrier concentration due to thermally excited defects. The defects produced by ion irradiation play a vital role in modifying the properties of semiconducting nanowires.

Focused Ion Beam Reduced Graphene Oxide Micro-Supercapacitors with Unprecedented Energy and Power Densitites

Miniaturization of energy storage devices with high energy and power densities can reduce the footprint of micro-devices being used in our daily life. Micro-supercapacitors with planar geometries offer several advantages, such as, the ability to control and reduce the distances ions travel between two electrodes, easy integration to micro devices as the separator and the electrodes are in the same plane, and offer the potential of being extended into 3D without compromising the inter-electrode separation distances. In this study, we have used focused ion beam technology (which is capable of producing reduced graphene oxide patterns and complex shapes in insulating films of graphene oxide with a possible spatial resolution down to ~20 nm in a mask-less and direct write approach) to directly write miniaturized planar electrodes of reduced graphene oxide on films of graphene oxide (GO). We have optimised the ion-beam irradiation and have investigated the influence of ion beam irradiation on the resultant microstructure and the electrochemical properties of the resultant reduced graphene oxide films. Subsequently, using the optimized ion-beam irradiation, interdigitated electrode designs (40 μm long and 3.5 μm wide fingers with ultra-small inter-electrode spacing of 1 μm) have been generated, which have demonstrated a large capacitance (102 mF/cm2), ultra-small time response (0.03 ms), low equivalent series resistance (0.35 mΩ cm2), and have retained 95 % of the specific capacitance after 1000 cycles at an ultrahigh current density of 45 mA/cm2. These performance metrics show unprecedented improvements on several aspects of supercapacitor performance over existing reports due to the miniaturized electrode dimensions and minimal damage to the graphene sheets. We believe our results can provide opportunities for large-scale fabrication of arrayed, planar, high performance micro-supercapacitors with a small environmental footprint.

Interface modification of Ag/Co system: X-ray reflectivity study

The influence of ion beam irradiation on structures, mainly of surface and interfaces, of a bilayer system, Ag/Co, deposited sequentially on Si(0 0 1) substrate by dc magnetron sputtering, is studied by X-ray reflectivity measurements. Films are irradiated by rastering with 150 keV Ar 2+ ion beam at fluences 1 × 10 14 and 5 × 10 14 ions/cm 2 and X-ray reflectivity data are collected in specular geometry. Experimental data were fitted with a non-linear least square fitting program and from that film thickness, surface and interface roughness and electron density profile along the growth direction are found out. It is observed that for both ion fluences the thickness of both films decreased and electron densities increased. The interface has become sharper than that of the as grown sample for lower fluence and Ag is found to be in Co layer at higher fluence, which could have happened due to ballistic effect. The thickness reduction and electron density increase indicate rearrangement of the atoms in close packed structure.

Stability of DRAM-devices with respect to 75 keV helium ion beam irradiation as required for ion projection lithography of critical layers

Abstract Ion projection lithography (IPL) is one of the next generation lithography techniques, targeting the 50-nm node and below. During the last year tool, mask and process development have made major advances. A resolution of 50 nm has been achieved locally, 75 nm over a field size of 12.5×12.5 mm 2 . Compatibility of ion projection lithography with a standard semiconductor process has not been proven so far. Possible device damage is still seen as a critical issue. Therefore experimental investigation of the influence of ion beam irradiation on the functionality of state-of-the-art chips is necessary. We carried out the experiment with a state-of-the-art DRAM product processed at a high volume production site. The experiment demonstrates that 75 keV He + ion beam exposure with ion doses as used for ion projection lithography would cause no detrimental damage. Thus IPL is suitable for semiconductor device fabrication.

Influence of ion beam irradiation on crystallographic structure and surface morphology of aluminium nitride thin films

Aluminum nitride (AlN) thin films have been synthesised by ion beam assisted deposition method, and the influence of ion beam irradiation on microstructure and surface morphology has been studied by thin film X-ray diffraction (TFXRD) and by atomic force microscopy (AFM). In order to elucidate the influence of ion beam irradiation on the crystallographic structure, 10 nm thick c-axis oriented films synthesised with the ion beam energy of 0.05 keV are irradiated with nitrogen ions of 0.5 keV (no aluminum evaporation) after deposition for the same period as the deposition time and this process is repeated until the film grows to 200 nm in thickness. The TFXRD results reveal that the “piled up” films do not show the oriented structure, but are disordered to the multi-oriented state. AFM observations reveal that (1) the films synthesised with the nitrogen ion beam of 0.05 keV show the extreme smooth surface and the surface roughness increases with increasing the nitrogen ion beam energy and (2) the film surface synthesised with the ion beam energy of 0.05 keV does not change drastically by 2-keV ion beam irradiation after deposition. These results show that synthesis with high energy ion beam makes AlN films disordered structure and rough surface.

Application of dynamic ion mixing in platinum silicide formation

Results concerning platinum silicide formation by dynamic mixing (ion mixing during Pt film deposition) are presented. The influence of ion beam irradiation on the growth kinetics of a platinum silicide layer formed by vacuum deposition of Pt atoms and simultaneous ion irradiation was investigated. The Pt atoms were deposited onto silicon substrate (both crystalline and amorphous) during 150 keV energy Ar + ion irradiation. Temperature of the substrate during deposition was varied from 300 to 800 K, Pt atom flux was equal to 2 x 10 14 cm -2 s -1, ion beam flux density varied from 5 x 10 11 to 6 x 10 12 cm -2 s -1 (ion dose 10 15-1. 1 x 10 16 cm -2). After deposition the Pt-Si structures were ennealed at temperatures in the range 400–1300 K. The composition of the deposits (as-deposited and annealed at 400–1300 K) was investigated by means of Rutherford backscattering spectroscopy, the structure of the Pt-Si system was studied by X-ray diffraction. A linear dependence of the reacted Pt 2Si layer thickness on the ion flux density (or ion dose) was found if deposition was conducted at room temperature on crystalline silicon. Dynamic mixing at elevated substrate temperatures (400–700 K) causes formation of a thermally unstable inhomogeneous layer consisting of Pt 2Si and silicide with excess of Pt. If dynamic mixing is provided at temperature 800 K and higher direct PtSi layer formation is possible.