Optical properties of SrxBa1−xNb2O6 nanoscale films (x = 0.5 and 0.61) grown by RF-cathode sputtering in an oxygen atmosphere

The research findings of the phase composition, nanostructure and optical properties of strontium–barium niobate thin films are discussed. Sr[Formula: see text]Ba[Formula: see text]Nb2O6 nanosized films ([Formula: see text] = 0.5 and 0.61) were characterized by XRD, SEM and AFM studies. Reflective multi-angle ellipsometry and spectrophotometry were used to determine the optical parameters (refractive index, its dispersion, and thickness of the damaged surface layer) of thin films. It was shown that SBN-50 and SBN-61 thin films were grown [Formula: see text]-oriented on Al2O3 (0001) and heteroepitaxial on MgO (001) substrates. The increase of refractive index, approaching its maximum value in the bulk material for a given composition as the film thickness increases, is observed.

Наносетчатые пленки из углеродных нанотрубок с Х-соединениями для электронных и фотовольтаических приложений

The atomic structure, electronic and optoelectronic properties of nanosized films of carbon nanotubes with seamless cross-shaped X- junctions are studied. It is established that the topology of the arrangement of non-hexagonal elements in the contact region of nanotubes determines the energy stability of the atomic structure. It is revealed that the pore size of the film determines the type of conductivity. At the smallest pore sizes, the film is characterized by a metallic type of conductivity; with an increase in pore size, the gap in the band structure also increases and the film becomes semiconductor. Films with a minimum gap size exhibit good photovoltaic properties. The photocurrent for the considered film models can reach 2.4 mA•cm-2 in the atmosphere and 3.25 mA•cm-2 outside the atmosphere. The presence of a gap in the band structure makes nanosized films promising for nanoelectronics and optoelectronics.

Optical and magnetic properties of Al/NiFe and Al/Ge/NiFe nanosized films

Nanosized films with ferromagnetic layers are widely used in nanoelectronics, sensor systems and telecommunication. The physical and magnetic properties of nanolayers may significantly differ from those known for bulk materials due to fine crystalline structure, influence of interfaces, roughness, and diffusion. In this work, we are employing a spectral ellipsometry method, magneto-optical Kerr magnetometry and VSM to investigate the impact of layer thickness on the optical constants and magnetization processes for two and three layer films of the type Al/NiFe/sitall, Al/Ge/NiFe/sitall on sitall substrate for different thickness of the upper Al layers. The refractive indexes of two layer films are well resolved by spectral ellipsometry demonstrating their good quality. Modelling data for three-layer films show considerable discrepancy with the experiment, which can be related to a stronger influence of interfaces. The magnetization processes of two-layer films weakly depend on the type and thickness of the upper non-ferromagnetic layers. However, the coercivity of three layer films may significantly change with the thickness of the upper layer: more than twice when the thickness of Al layer increases from 4 to 20 nm.