Optical properties of ZnO and Al2O3 implanted with silver ions

ZnO and Al2O3 samples implanted with 30-keV silver ions with fluences in the interval (0.25-1.00) × 1017 ions/cm2 are studied by the method of optical photometry in the visible part of the spectrum. The optical transmission spectra of the implanted samples exhibit a selective band associated with surface plasmon resonance absorption of silver nanoparticles. The intensity of this band nonmonotonically depends on the implantation fluence. The silver ion depth distribution in the samples is calculated. It is shown that the non-monotonicity observed in experiments is due to an increase in the substrate sputtering ratio with increasing implantation fluence. It is found that vacuum thermal annealing of the implanted Al2O3 layers up to 700°C causes a considerable narrowing of the plasmon absorption bandwidth without a tangible change in its intensity. At higher annealing temperatures, the plasmon absorption band broadens and its intensity drops. Annealing of the ZnO films under such conditions causes their complete vaporization. © 2014 Pleiades Publishing, Ltd

Effects of nickel ions implantation and subsequent thermal annealing on structural and magnetic properties of titanium dioxide

© Published under licence by IOP Publishing Ltd. Wide bandgap semiconducting rutile (TiO2) doped with 3d-elements is a promising material for spintronic applications. In our work a composite material of TiO2:Ni has been formed by using implantation of Ni+ ions into single-crystalline (100)- and (001)- plates of TiO2. Sub-micron magnetic layers of TiO2 containing nickel dopant have been obtained at high implantation fluence of 1×1017 ion/cm2. A part of the implanted samples was then annealed in vacuum at different temperatures T ann 450-1200 K for 30 min. The influence of the implantation fluence, crystalline orientation, as well as subsequent annealing on the structural and magnetic properties of the nickel-implanted TiO2 have been investigated by using X-ray photoelectron spectroscopy, scanning electron microscopy and coil magnetometry techniques

Effect of implantation regimes of silver ions on the structure and optical properties of zinc-oxide nanocrystalline films

© 2016, Pleiades Publishing, Ltd.Thin (about 270 nm) nanocrystalline films of zinc oxide (ZnO) are obtained on quartz substrates using ion sputtering and irradiated with Ag+ ions at an energy of 30 keV and relatively high fluences at ion current densities of 4, 8, and 12 µA/cm2. The X-ray analysis, scanning electron microscopy, and optical spectroscopy are used to study the effect of irradiation dose and ion current density on the structural modification and optical properties of the ZnO films. Nontrivial dependences of the structural and optical parameters of the films on the ion irradiation regimes are due to radiation heating and film sputtering under the action of the ion beam, diffusion of impurity, formation of silver nanoparticles in the irradiated layer at high implantation fluences, and the diffusion of implanted impurity at relatively high ion current densities

Optical and electrical studies of ZnO thin films heavily implanted with silver ions

© Published under licence by IOP Publishing Ltd. Thin films of zinc oxide (ZnO) with the thickness of 200 nm have been deposited on quartz substrates by using ion-beam sputtering technique. Then Ag+ ions with the energy of 30 keV have been implanted into as-deposited ZnO films to the fluences in the range of (0.25-1.00)×1017 ions/cm2 to form ZnO:Ag composite layers with different concentrations of the silver impurity. The analysis of the microstructure has shown that the thickness of the ZnO film decreases, and the Ag dopant concentration tends to the saturation with increasing Ag implantation fluence. The ZnO:Ag composite layers reveal the optical selective absorption at the wavelength of the surface plasmon resonance that is typical for silver nanoparticles dispersed in the ZnO matrix. The red shift of the plasmon resonance peak from 480 to 500 nm is observed with the increase in the implantation fluence to 0.75×1017 Ag ions/cm2. Then the absorption peak position starts the backward motion, and the absorption intensity decreases with the subsequent increase in the implantation fluence. The non-monotonic dependence of the absorption peak position on the implantation fluence has been analyzed within of Maxwell Garnet theory and taking into account the strong sputtering of ZnO films during implantation. The ZnO:Ag composite layers exhibit the p-type conductivity indicating that a part of Ag+ ions is in the form of acceptor impurities implanted into the ZnO lattice

Introduction to geographic information systems (GIS)

The presentation reviews the development and application of geographic information systems (GIS) in terms of its capacity to store information about the world as a collection of thematic layers that can be linked together by geography. The real world consists of many geographies which in GIS can be represented with a number of related data layers such as: hydrology, topography, land use, soil, streets, utilities, districts etc. GIS analytical capabilities provide access to raw data, which can then be aggregated or reclassified

Microstructure and magnetooptics of silicon oxide with implanted nickel nanoparticles

Metallic nickel nanoparticles of various sizes are formed in a thin near-surface layer in an amorphous SiO 2 matrix during 40-keV Ni + ion implantation at a dose of (0.25-1.0) × 10 17 ions/cm 2. The microstructure of the irradiated layer and the crystal structure, morphology, and sizes of nickel particles formed at various irradiation doses are studied by transmission electron microscopy and electron diffraction. The magnetooptical Faraday effect and the magnetic circular dichroism in an ensemble of nickel nanoparticles are studied in the optical range. The permittivity ε∧ tensor components are calculated for the implanted samples using an effective medium model with allowance for the results of magnetooptical measurements. The spectral dependences of the tensor ε∧ components are found to be strongly different from those of a continuous metallic nickel film. These differences are related to a disperse structure of the magnetic nickel phase and to a surface plasma resonance in the metal nanoparticles. © Pleiades Publishing, Inc., 2011

Structure and optical properties of ZnO with silver nanoparticles

© 2016, Pleiades Publishing, Ltd. Textured nanocrystalline ZnO thin films are synthesized by ion beam assisted deposition. According to X-ray diffraction data, the crystallite size is ~25 nm. Thin (~15 nm) ZnO layers containing Ag nanoparticles are formed in a thin surface region of the films by the implantation of Ag ions with an energy of 30 keV and a dose in the range (0.25–1) × 1017 ion/cm2. The structure and optical properties of the layers are studied. Histograms of the size distribution of Ag nanoparticles are obtained. The average size of the Ag nanoparticles varies from 0.5 to 1.5–2 nm depending on the Ag-ion implantation dose. The optical transmittance of the samples in the visible and ultraviolet regions increases, as the implantation dose is increased. The spectra of the absorption coefficient of the implanted films are calculated in the context of the (absorbing film)/(transparent substrate) model. It is found that the main changes in the optical-density spectra occur in the region of ~380 nm, in which the major contribution to absorption is made by Ag nanoparticles smaller than 0.75 nm in diameter. In this spectral region, absorption gradually decreases, as the Ag-ion irradiation dose is increased. This is attributed to an increase in the average size of the Ag nanoparticles. It is established that the broad surface-plasmon-resonance absorption bands typical of nanocomposite ZnO films with Ag nanoparticles synthesized by ion implantation are defined by the fact that the size of the nanoparticles formed does not exceed 1.5–2 nm

Study of morphology, magnetic properties, and visible magnetic circular dichroism of Ni nanoparticles synthesized in SiO2 by ion implantation

A systematic study of ensembles of nickel nanoparticles fabricated by Ni+-ion implantation at a dose of (0.5-1.0)×1017 ions/cm2 in a thin near-surface layer of an amorphous SiO2 matrix by means of transmission electron microscopy (TEM), dc magnetic measurements, and magneto-optical technique is presented. TEM characterization of Ni nanoparticles proves the formation of isolated spherical nickel nanoparticles with diameters from 2 to 16 nm. The crystal structure and lattice constant of the nanoparticles correspond to face-centered-cubic Ni. The larger size nanoparticles are shown to have core-shell structure, which is unusual for the implantation conditions used. The shell of these nanoparticles consists of Ni, while the core has supposedly the composition coinciding with the matrix, i.e., SiO2. The core-shell nanoparticles in the investigated sample coexist with ordinary pure Ni nanoparticles, which strongly affects the magnetic and especially magneto-optic properties of the samples. For all three doses, the nanoparticles are in the superparamagnetic state at room temperature passing to the "frozen" state at lower temperatures. However, only the sample implanted with the lowest dose demonstrates the classic superparamagnetic behavior according to the shape of the experimental magnetization temperature dependencies for the zero-field-cooled (ZFC) and field-cooled regimes. This shape deviation from that characteristic of the pure superparamagnetic ensembles is ascribed mainly to the particle core-shell structure. The Ni nanoparticles' anisotropy constant estimated with the help of ZFC curves appears to exceed the bulk Ni anisotropy second constant approximately by two orders of magnitude. Magnetic circular dichroism (MCD) is characterized by spectral dependence modified strongly as compared to the MCD spectra of a continuous Ni film. In the spectral range 1.1-4.2 eV, the MCD spectrum consists of two broad maxima of opposite sign with the characteristics depending on the implantation dose and the measurement temperature. The MCD spectra analysis allows one to show that the higher-energy maximum (at 3.34-3.48 eV depending on the dose) is related to the surface plasmon resonance (SPR) excitation in pure Ni nanoparticles, while the lower-energy maximum (at 2.19-2.73 eV depending on the dose) should be associated with the SPR excitation in core-shell nanoparticles. © 2013 American Physical Society

Scanning Probe Microscopy of silicon layers after Ag+ implantation

Описан способ формирования нанопористого кремния на поверхности монокристаллического Si при имплантации ионами Ag+. Методами СЗМ и СЭМ показано, что в результате на поверхности Si формируются аморфные слои нанопористого кремния со средними размерами пор ~130 нм, в структуре которых синтезируются наночастицы Ag диаметром от 5 до 20 нм.An idea to create nanoporous silicon layers by low-energy high-dose Ag-ion implantation was realized. Surface structures were analyzed by scanning electron microscopy and scanning probe microscopy. It is shown that as a result there are a porous structure with a characteristic size ~130 nm on Si surface with Ag nanoparticles (diameter 5-20nm) inside.Работа выполнена при финансовой поддержке РНФ № 17-12-01176