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The preparation of non-oxidized Ge quantum dot (QD) lattices embedded in Al2O3, Si3N4, SiC matrices by self-assembled growth was studied. The materials were produced by magnetron sputtering deposition, using different substrate temperatures. The deposition regimes leading to the self-assembled growth type and the formation of three-dimensionally ordered Ge QD lattices in different matrices were investigated and determined. The oxidation of the Ge QDs in different matrices was monitored and the best conditions for the production of non-oxidized Ge QDs were found. The optical properties of the Ge QD lattices in different matrices show a strong dependence on the Ge oxidation and the matrix type.

Ge/Si core/shell quantum dots (QDs) recently received extensive attention due to their specific properties induced by the confinement effects of the core and shell structure. They have a type II confinement resulting in spatially separated charge carriers, the electronic structure strongly dependent on the core and shell size. Herein, the experimental realization of Ge/Si core/shell QDs with strongly tunable optical properties is demonstrated. QDs embedded in an amorphous alumina glass matrix are produced by simple magnetron sputtering deposition. In addition, they are regularly arranged within the matrix due to their self-assembled growth regime. QDs with different Ge core and Si shell sizes are made. These core/shell structures have a significantly stronger absorption compared to pure Ge QDs and a highly tunable absorption peak dependent on the size of the core and shell. The optical properties are in agreement with recent theoretical predictions showing the dramatic influence of the shell size on optical gap, resulting in 0.7 eV blue shift for only 0.4 nm decrease at the shell thickness. Therefore, these materials are very promising for light-harvesting applications.

In the present work we investigate effects ofMeVheavy ions (from 0.4 MeVXe to 15 MeVSi) on regularly ordered nanoparticle (NP) lattices embedded in amorphous alumina matrix. These nanostructures were produced by self-assembling growth using magnetron-sputtering deposition. From grazing incidence small-angle x-ray scattering measurements we have found that the usedMeV heavy ions do not change the NPsizes, shapes or distances among them. However, ions cause a tilt of the entire NP lattice in the direction parallel to the surface. The tilt angle depends on the incident ion energy, type and the applied fluence and a nearly linear increase of the tilt angle with the ion fluence and irradiation angle was found. This way,MeV heavy ion irradiation can be used to design custom-made NPlattices. In addition, grazing incidence small-angle x-ray scattering can be effectively used as a method for the determination of material redistribution/shift caused by the ion hammering effect. For the first time, the deformation yield in amorphous alumina was determined for irradiation performed at the room temperature.

Simple fabrication processes of Ge-based nanostructures in glasses are very interesting due to the highly tuneable electronic structure and many relevant applications. We address the recent advances in the production of regularly ordered Ge/Si and Ge/metal core/shell nanostructures formed by magnetron sputtering deposition in glass alumina matrix [1]. The regular ordering of these nanostructures is achieved by the self-ordering growth regime that occurs under specific deposition conditions [2]. We have developed the theory and software for the analysis of such materials by small grazing incidence angle x ray scattering (GISAXS) [3]. The light absorption properties of these films are significantly different compared to films that form quantum dot lattices of the pure Ge, Si, metal or a solid solution of the constituents. The Ge/Si core/shell quantum dots show a strong narrow absorption peak that characterizes a type II confinement in accordance with the theoretical predictions. In addition, we show that the peak position and width depend strongly on the size of Ge core and Si shell [4]. These materials are very interesting for the application in quantum dot solar cells. [1] M. Buljan, et al., Nanotechnology 26 065602 (2015). [2] M. Buljan, et al., J. Appl. Cryst. 46, 1490-1500 (2013). [3] M. Buljan, et al., Acta Cryst. A, 68, 124 (2012); http://homer.zpr.fer.hr/gisaxstudio/doku.php [4] N. Nekic, et al., (in preparation)

We investigated the response of wurzite GaN thin films to energetic ion irradiation. Both swift heavy ions (92 MeV Xe23+, 23 MeV I6+) and highly charged ions (100 keV Xe40+) were used. After irradiation, the samples were investigated using atomic force microscopy, grazing incidence small angle x-ray scattering, Rutherford backscattering spectroscopy in channelling orientation and time of flight elastic recoil detection analysis. Only grazing incidence swift heavy ion irradiation induced changes on the surface of the GaN, when the appearance of nanoholes is accompanied by a notable loss of nitrogen. The results are discussed in the framework of the thermal spike model.

We report on the formation of Ge/Si quantum dots with core/shell structure that are arranged in a three-dimensional body centered tetragonal quantum dot lattice in an amorphous alumina matrix. The material is prepared by magnetron sputtering deposition of Al2 O3 /Ge/Si multilayer. The inversion of Ge and Si in the deposition sequence results in the formation of thin Si/Ge layers instead of the dots. Both materials show an atomically sharp interface between the Ge and Si parts of the dots and layers. They have an amorphous internal structure that can be crystallized by an annealing treatment. The light absorption properties of these complex materials are significantly different compared to films that form quantum dot lattices of the pure Ge, Si or a solid solution of GeSi. They show a strong narrow absorption peak that characterizes a type II confinement in accordance with theoretical predictions. The prepared materials are promising for application in quantum dot solar cells.

The SYRMEP (synchrotron radiation in medical physics) Collaboration is planning to use a beam of monochromatic x-rays provided by Elettra, the synchrotron radiation facility in operation at Trieste (Italy), in conjunction with a novel silicon pixel detector to conduct research in digital mammography. A beamline dedicated to mammography is presently under construction in Trieste; it will provide, at a distance of about 20 m from an Elettra bending magnet, a monochromatic laminar-section (150×4 mm2) x-ray beam. This beam will illuminate in vitro samples and will be detected by a fixed silicon microstrip device forming a matrix of pixels. Digital images of phantoms having a size common in the diagnostic practice (150×150 mm2), can then be produced by scanning the sample itself in front of the detector. A prototype detector with a sensitive area of 24×1 mm2 and pixels of 0.5×0.5 mm2 has been built and tested. We present the current status of the SYRMEP beamline and a digital image of a mammographic phantom exposed to a radioactive x-ray source.

Recent advances in vacuum sciences and applications are reviewed. Novel optical interferometer cavity devices enable pressure measurements with ppm accuracy. The innovative dynamic vacuum standard allows for pressure measurements with temporal resolution of 2 ms. Vacuum issues in the construction of huge ultra-high vacuum devices worldwide are reviewed. Recent advances in surface science and thin films include new phenomena observed in electron transport near solid surfaces as well as novel results on the properties of carbon nanomaterials. Precise techniques for surface and thin-film characterization have been applied in the conservation technology of cultural heritage objects and recent advances in the characterization of biointerfaces are presented. The combination of various vacuum and atmospheric-pressure techniques enables an insight into the complex phenomena of protein and other biomolecule conformations on solid surfaces. Studying these phenomena at solid-liquid interfaces is regarded as the main issue in the development of alternative techniques for drug delivery, tissue engineering and thus the development of innovative techniques for curing cancer and cardiovascular diseases. A review on recent advances in plasma medicine is presented as well as novel hypotheses on cell apoptosis upon treatment with gaseous plasma. Finally, recent advances in plasma nanoscience are illustrated with several examples and a roadmap for future activities is presented. © 2014 IOP Publishing Ltd.

We present the formation of ordered 3D lattice of Ni nanocrystals/nanoparticles in amorphous alumina matrix achieved by a self-assembly process during a single-step magnetron sputtering deposition of Ni/Al2O3 multilayer at room temperature. The structure of the films was analyzed using Grazing Incidence Small and Wide Angle X-ray Scattering, Transmission Electron Microscopy, Atomic Force Microscopy, Grazing Incidence Wide Angle X-ray Scattering, and Time-of-Flight Elastic Recoil Detection Analysis measurements. The self-assembly is driven by surface morphology effects and it results in a body-centered tetragonal (BCT) lattice of Ni particles with crystalline face-centered cubic (FCC) internal structure in amorphous Al2O3 matrix. The size distribution of Ni NPs is narrow, and the material has good mechanical properties due to the alumina matrix. We show that the NP sizes and separations can be easily tuned by a suitable choice of the deposition conditions. The quality of the ordering achieved in the alumina matrix is found to be significantly better than the ordering of Ni particles in silica. The obtained results are important for the understanding of the self-assembly process of metallic particles in amorphous matrices and the applications of such materials. The prepared materials are potentially interesting for spintronic applications.

We present the formation of an ordered three-dimensional lattice of Ni nanocrystals in an amorphous alumina matrix by a self-assembly process. The self-assembled growth achieved by single-step magnetron sputtering deposition of a Ni/Al2O3 multilayer is driven by surface morphology effects. The influence of the Ni layer thickness on the Ni particle size, separation, and quality of ordering is examined. The quality of Ni nanoparticles ordering in alumina is compared to their ordering in a silica matrix. The obtained results are important for the understanding of the self-assembly process of metallic particles in amorphous matrices and the applications of such materials.

We present the formation of ordered 3D lattice of Ni nanocrystals/nanoparticles in amorphous alumina matrix achieved by a self-assembly process during a single-step magnetron sputtering deposition of Ni/Al2O3 multilayer at room temperature. The structure of the films was analyzed using Grazing Incidence Small and Wide Angle X-ray Scattering, Transmission Electron Microscopy, Atomic Force Microscopy, Grazing Incidence Wide Angle X-ray Scattering, and Time-of-Flight Elastic Recoil Detection Analysis measurements. The self-assembly is driven by surface morphology effects and it results in a body-centered tetragonal (BCT) lattice of Ni particles with crystalline face-centered cubic (FCC) internal structure in amorphous Al2O3 matrix. The size distribution of Ni NPs is narrow, and the material has good mechanical properties due to the alumina matrix. We show that the NP sizes and separations can be easily tuned by a suitable choice of the deposition conditions. The quality of the ordering achieved in the alumina matrix is found to be significantly better than the ordering of Ni particles in silica. The obtained results are important for the understanding of the self-assembly process of metallic particles in amorphous matrices and the applications of such materials. The prepared materials are potentially interesting for spintronic applications.

Recent advances in vacuum sciences and applications are reviewed. Novel optical interferometer cavity devices enable pressure measurements with ppm accuracy. The innovative dynamic vacuum standard allows for pressure measurements with temporal resolution of 2 ms. Vacuum issues in the construction of huge ultra-high vacuum devices worldwide are reviewed. Recent advances in surface science and thin films include new phenomena observed in electron transport near solid surfaces as well as novel results on the properties of carbon nanomaterials. Precise techniques for surface and thin-film characterization have been applied in the conservation technology of cultural heritage objects and recent advances in the characterization of biointerfaces are presented. The combination of various vacuum and atmospheric-pressure techniques enables an insight into the complex phenomena of protein and other biomolecule conformations on solid surfaces. Studying these phenomena at solid-liquid interfaces is regarded as the main issue in the development of alternative techniques for drug delivery, tissue engineering and thus the development of innovative techniques for curing cancer and cardiovascular diseases. A review on recent advances in plasma medicine is presented as well as novel hypotheses on cell apoptosis upon treatment with gaseous plasma. Finally, recent advances in plasma nanoscience are illustrated with several examples and a roadmap for future activities is presented. © 2014 IOP Publishing Ltd.

Simple processes for the preparation of semiconductor quantum dot lattices embedded in dielectric amorphous matrices play an important role in various nanotechnology applications. Of particular interest are quantum dot lattices with properties that differ significantly in different directions parallel to the material surface. Here, a simple method is demonstrated for the fabrication of an anisotropic lattice of Ge quantum dots in an amorphous Al2O3 matrix by a self-assembly process. A specific deposition geometry with an oblique incidence of the Ge and Al2O3 adparticles was used during magnetron sputtering deposition to achieve the desired anisotropy. The observed Ge quantum dot ordering is explained by a combination of directional diffusion of adparticles from the Ge and Al(2)O(3)targets and a shadowing process which occurs during deposition as a result of the specific surface morphology. The prepared material shows a strong anisotropy of the electrical conductivity in different directions parallel to the sample surface.

In this article we show how to produce materials consisting of regularly ordered Ge quantum dots in amorphous alumina matrix with the controllable Ge quantum dot size, shape, spacing, crystalline structure and degree of regularity in the Ge quantum dot ordering. The production of such materials is achievable already at room temperature by magnetron sputtering deposition of a (Ge+Al2O3)/Al2O3 multilayer. The materials show large, size-dependent blueshift of the photoluminescence peak and enhancement in the oscillator strength caused by confinement effects. The materials also show advanced mechanical properties due to alumina matrix, and their internal structure is shown to be highly resistive to irradiation with energetic particles for a large range of the irradiation parameters. The reported materials have excellent potential for application in demanding environments for light harvesting.

In this work, we investigate the structural and photoluminescence (PL) properties of (SiGe+Al2O3)/Al2O3 multi-layer films with layer thicknesses in the range of a few nanometres. The films were prepared by magnetron sputtering deposition at room temperature followed by an annealing process to promote the formation of small SiGe nanocrystals (NCs) (∼3 to 5 nm) embedded between ultra-thin (∼6 nm thickness) Al2O3 layers. Our results show that the structural and compositional properties of the films can be tuned by changing the RF-power. It is found that nearly spherical and well confined isolated SiGe NCs (∼5 nm) are obtained for an RF-power value of 80 W. The PL properties of the films were studied and optical emission in the blue visible wavelength region was observed. © 2013 IOP Publishing Ltd.

We present an investigation of ordering and PL properties of Ge QDs in an alumina matrix formed by magnetron-sputtering deposition of (Ge+Al2O3)/Al2O3 multilayers. The self-assembly process occurs during the deposition and results with the formation of three-dimensional quantum dots lattices. We investigate the dependencies of the size and ordering properties on the deposition temperature, rotation of the substrate holder and direction of the incoming flux of Ge during the deposition process. The results of the investigation show that tuning the deposition temperature enables manipulation with QD sizes and their mutual distances. We show that the ordering of QDs obtained by deposition on fixed substrate holder leads to the formation of a quantum dot crystal, while the rotation of substrate holder leads to randomly rotated domains with regular ordering. The observed phenomenon is explained by a combination of the surface morphology effect on the nucleation positions of Ge quantum dots with a lateral inhomogeneity of the ad-atom flux. In addition, we show that the resulting quantum-dot lattices have size-dependent PL properties.

We report on an in-situ and ex-situ X-ray investigations of a self-assembled growth of Ge nanocrystals embedded in a dielectric matrix forming BCC- or FCC-like superstructures. Germanium quantum dots (QD’s) embedded in dielectric matrices like SiO2 [1] or Al2O3 [2] have numerous interesting properties e.g. a strong quantum confinement. They could be used in optoelectronic devices and memory systems. Such a material can be a key element for the development of a new generation of solar cells extending the spectral range for electrical energy generation, either for an up and/or down conversion of the incident photons or simply as one part of a multilayer stack arrangement.

In this work, the influence of air pressure during the annealing of Ge quantum dot (QD) lattices embedded in an amorphous Al2O3 matrix on the structural, morphological and compositional properties of the film is studied. The formation of a regularly ordered void lattice after performing a thermal annealing process is explored. Our results show that both the Ge desorption from the film and the regular ordering of the QDs are very sensitive to the annealing parameters. The conditions for the formation of a void lattice, a crystalline Ge QD lattice and a disordered QD lattice are presented. The observed effects are explained in terms of oxygen interaction with the Ge present in the film.

We report on an in-situ and ex-situ X-ray investigations of a self-assembled growth of Ge nanocrystals embedded in a dielectric matrix forming BCC- or FCC-like superstructures. Germanium quantum dots (QD’s) embedded in dielectric matrices like SiO2 [1] or Al2O3 [2] have numerous interesting properties e.g. a strong quantum confinement. They could be used in optoelectronic devices and memory systems. Such a material can be a key element for the development of a new generation of solar cells extending the spectral range for electrical energy generation, either for an up and/or down conversion of the incident photons or simply as one part of a multilayer stack arrangement.

We present an investigation of ordering and PL properties of Ge QDs in an alumina matrix formed by magnetron-sputtering deposition of (Ge+Al2O3)/Al2O3 multilayers. The self-assembly process occurs during the deposition and results with the formation of three-dimensional quantum dots lattices. We investigate the dependencies of the size and ordering properties on the deposition temperature, rotation of the substrate holder and direction of the incoming flux of Ge during the deposition process. The results of the investigation show that tuning the deposition temperature enables manipulation with QD sizes and their mutual distances. We show that the ordering of QDs obtained by deposition on fixed substrate holder leads to the formation of a quantum dot crystal, while the rotation of substrate holder leads to randomly rotated domains with regular ordering. The observed phenomenon is explained by a combination of the surface morphology effect on the nucleation positions of Ge quantum dots with a lateral inhomogeneity of the ad-atom flux. In addition, we show that the resulting quantum-dot lattices have size-dependent PL properties.

In this work we report on a self-assembled growth of a Ge quantum dot lattice in a single 600-nm-thick Ge+Al(2)O(3) layer during magnetron sputtering deposition of a Ge+Al(2)O(3) mixture at an elevated substrate temperature. The self-assembly results in the formation of a well-ordered three-dimensional body-centered tetragonal quantum dot lattice within the whole deposited volume. The quantum dots formed are very small in size (less than 4.0 nm), have a narrow size distribution and a large packing density. The parameters of the quantum dot lattice can be tuned by changing the deposition parameters. The self-ordering of the quantum dots is explained by diffusion-mediated nucleation and surface-morphology effects and simulated by a kinetic Monte Carlo model.

So far, the growth of spatially ordered nanoclusters by multilayer deposition has been reported and explained satisfactorily only in crystalline materials. Here we demonstrate a method for the growth of spatially ordered nanoclusters in amorphous matrices, where the ordering is achieved in the single large domain. The regular ordering is induced by the deposition of a multilayer on a periodically rippled substrate at an elevated substrate temperature. During the deposition, the nanoclusters self-arrange, following the morphology of the substrate.

We report on structural properties and charge trapping in [(Ge+SiO2)/SiO2]×2 films deposited by magnetron sputtering on a periodically corrugated-rippled substrate and annealed in vacuum and forming gas. The rippled substrate caused a self-ordered growth of Ge quantum dots, while annealing in different environments enabled us to separate charge trapping in quantum dots from the trapping at the dot-matrix and matrix-substrate interfaces. We show that the charge trapping occurs mainly in Ge quantum dots in the films annealed in the forming gas, while Si–SiO2 interface trapping is dominant for the vacuum annealed films.

We report on the formation of a regularly ordered void lattice with a void size of about 4 nm in an alumina matrix. The voids were formed by thermal treatment of a well-ordered three-dimensional Ge quantum dot lattice formed earlier by self-assembled growth in an alumina matrix during magnetron sputtering codeposition of Ge+Al2O3. During the subsequent annealing the germanium atoms were lost from the film and so voids were produced. The positions of the voids are ordered in the same way as the Ge quantum dots that were present before annealing, while their sizes can be controlled by the deposition parameters.

We have deposited a 12 nm thick Ge layer on Si(1 0 0) held at 200 °C by thermal evaporation under high vacuum conditions. Upon subsequent thermal annealing in vacuum, self-assembled growth of nanostructural Ge islands on the Ge layer occurred. Atomic force microscopy (AFM) and grazing incidence small-angle X-ray scattering (GISAXS) were used to characterize such layers. GISAXS measurements evidenced the formation of cylinder shaped structures upon annealing at 700 °C, which was confirmed by AFM measurements with a very sharp tip. A Ge mass transport from the layer to the islands was inferred by X-ray reflectivity and an activation energy of 0.40 ± 0.10 eV for such a process was calculated. © 2006 Elsevier B.V. All rights reserved.

Grazing incidence small angle scattering of X-rays (GISAXS) was used to analyze structural modifications in implantation-damaged Ge. Samples were implanted by different doses of 74Ge, from 3 × 1012 cm-2 to 3 × 1016 cm-2; at room- or liquid nitrogen-temp

Czochralski-grown dislocation-free silicon is used in the semiconductor industry almost exclusively for manufacturing VLSI devices. Such material contains small quantities (similar to20 ppm) of dissolved oxygen, which can have a crucial effect on the properties of produced devices. Therefore it is of great importance to study its precipitation in a silicon matrix after given thermal treatment. The small angle X-ray scattering (SAXS) technique was used to study oxygen precipitation in monocrystalline silicon samples. We used 8 and 16 keV radiation to overcome the high absorption at low energies. A series of samples has been prepared with controlled sequence of oxygen nucleation and precipitation phase and measured with SAXS. It is shown that this low contrast changes in standard wafers can be investigated using synchrotron radiation. (C) 2002 Elsevier Science B.V. All rights reserved.