We theoretically interpret the thermal behaviour of the average radius versus substrate temperature of regular quantum dot/nanocluster arrays formed by sputtering semiconductor/metal atoms with oxide ...molecules. The analysis relies on a continuum theory for amorphous films with given surface quantities, perturbed by a nanoparticle lattice. An account of the basic thermodynamic contributions is given in terms of force-flux phenomenological coefficients of each phase (Ge, Ni, Al2O3). Average radii turn out to be expressible by a characteristic length scale and a dimensionless parameter, which mainly depend upon temperature through diffusion lengths, film pressures and finite-size corrections to interfacial tensions. The numerical agreement is good in both Ge (4%) and Ni (15.4%) lattices grown at temperatures ⩽800 K, despite the lower temperature behaviour of quantum dots seeming to suggest further driving forces taking part in such processes.
Simple and efficient methods for the accurate structural characterization of ion-beam modified materials are important due to their interesting properties and many applications. Here we demonstrate ...the application of the Grazing incidence small angle X-ray scattering (GISAXS) method on the structural analysis of swift heavy ion-beam modified materials. Passing through a material, an accelerated ion usually modifies its surrounding causing the formation of nano-objects along its trajectory, called ion track. We show that GISAXS can be used to determine the structural properties of the nano-objects formed along the ion tracks, as well as their ordering properties. We have developed theoretical models describing GISAXS intensity distributions of the systems having different ordering types. The efficiencies of the models are tested on experimental examples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Multilayer thin films consisting of 10 bilayers of (Al2O3+Ni)/Al2O3 were deposited by magnetron sputtering onto Si(100) substrate. Nickel nanoparticles are formed inside amorphous alumina matrix by ...self-assembly growth process. It was determined by GISAXS measurements that nickel particles are spheroidal with diameter < 3 nm and that they form paracrystal-like body-centered tetragonal lattice. Magnetic properties of the prepared thin films were studied. Due to the nanometer size of nickel particles, their magnetic structure is single domain and they show superparamagnetic behaviour. Anisotropy of magnetic properties was observed when magnetic field is applied parallel or perpendicular to the thin film surface and it was attributed to dipole-dipole interactions between particles. This was confirmed using simulations of the M(H) curve of the 2D superlattice of the identical superparamagnetic particles, which was performed using Monte Carlo method and Metropolis algorithm.
In the present work, a method for the low-temperature production of the material consisting of closely packed Ge QDs embedded in ITO matrix is described. The films are produced by magnetron ...sputtering deposition followed by thermal annealing. It is shown that the conductivity and optical properties of the films depend on the structure, Ge content in the ITO matrix as well as on the annealing conditions. The conductivity of the films changes up to seven orders of magnitude in dependence on the annealing conditions, and it shows transformation from semiconductor to metallic behavior. The optical properties are also strongly affected by the preparation and annealing conditions, so both conductivity and optical properties can be controllably manipulated. In addition, the crystallization of Ge is found to occur already at 300 C, which is significantly lower than the crystallization temperature of Ge produced by the same method in silica and alumina matrices.
We theoretically interpret the thermal behaviour of the average radius versus substrate temperature of regular quantum dot/nanocluster arrays formed by sputtering semiconductor/metal atoms with oxide ...molecules. The analysis relies on a continuum theory for amorphous films with given surface quantities, perturbed by a nanoparticle lattice. An account of the basic thermodynamic contributions is given in terms of force-flux phenomenological coefficients of each phase (Ge, Ni, Al
O
). Average radii turn out to be expressible by a characteristic length scale and a dimensionless parameter, which mainly depend upon temperature through diffusion lengths, film pressures and finite-size corrections to interfacial tensions. The numerical agreement is good in both Ge (Formula: see text) and Ni (Formula: see text) lattices grown at temperatures Formula: see text800 K, despite the lower temperature behaviour of quantum dots seeming to suggest further driving forces taking part in such processes.
The growth defects in magnetron sputtered coatings have been well studied in industrial environment. In this work, on the other hand, the emphasis is in observing the same phenomena in a lab-scale ...UHV environment. TiN and CrN films were deposited at a thickness of 1–2 μm. The statistical evaluation of defect density was based on stylus profilometry scans (2 mm2 area), and consequent analysis of hillock density in dependence of threshold height. Morphology of defects was observed by SEM, while on selected defects we made FIB cross-sections. In this way we were able to measure the chemical composition of individual seeds – starting points for growth defects. In contrast to expectations, there was only a relatively minor reduction of defect density by using UHV environment.
•Growth defects were studied in TiN and CrN films deposited in UHV.•Compared to industrial coatings, the density is smaller but not substantially.•The geometry and morphology of defects is similar to the ones in industrial coatings.•The seed composition was either identical to the film, or traced to foreign splinters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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