Solid State Phenomena Vol. 245

Abstract: The paper presents the theoretical calculations of the structure and morphology of ZrO₂ nanocrystals. The equilibrium morphology shapes of tetragonal and cubic nanocrystals were determined. It was shown that the equilibrium morphology was determined by an appropriate set of faces of tetragonal and cubic phases of zirconium oxide.

Abstract: The optical properties of ordered arrays of silicon nanorods (Si NRs) were investigated. Electron Beam Lithography followed by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE) was used for Si NRs fabrication. Si NRs were chemically and electrically passivated through the deposition of TiONx nanolayer. Tunable color generation from vertical silicon nanorods is demonstrated too.

Abstract: This paper deals with the elastic properties of pure and nitrogen-doped silicene using density functional theory. During the compression (tension) from –2 to 2 GPa of pure and nitrogen-doped silicene, the corresponding values for the bulk modulus are obtained. It is found that the doping of the silicene structure with nitrogen has practically no effect on the value of its bulk modulus. However, the Young's modulus is increased of about 1.25 times.

Abstract: We study stable stable transparent monolithic nanocomposites based on the silica matrix doped with CdS nanoparticles (NPs) of different nature. The first kind of nanocomposite was obtained by nucleation and growth of nanoparticles in glass matrix during heat treatment. The second nanocomposite was obtained by immobilization of pre-made nanoparticles into silica gel matrix. This work is focused on characterization of the nanocomposites in the submicron scale by using electron microscopy and small angle x-ray scattering techniques. Experimental results show that both types of nanocomposites have homogeneous distribution of quantum dots. Form-factor and average size of CdS NPs depend on the synthesis technique

Abstract: In the model of finite number (up to 24) of point Ising-like magnetic dipoles with magnetostatic interaction on square 2D lattice within the framework of statistical physics, with using Gibbs formalism and by the means of Metropolis algorithm the heating dependence of temperature has been evaluated. The temperature dependence of the heat capacity on finite number of point dipoles has the finite value of maximum. Together with increase of the system in size the heating peak grows and moves to the area with higher temperature. The obtained results are useful in experimental verification of statistical models, as well as in development and testing of approximate calculation methods of systems with great number of particles.

Abstract: There has been carried out comparative analysis of energy minimizing methods in systems of magnetic Ising dipoles, randomly distributed on the nonmagnetic plane. The considered methods of ground state search are based on alignment of a magnetic moment of dipole in direction of an internal magnetic field. It is found out that the rate of convergence is low in the used methods, based on collective flipping of group of particles

Abstract: Literature data on the effective electrical injectors of electron spin for silicon spintronics and stages of the investigation of corresponding magnetic tunnel contacts are reviewed up to 2015 year and a consideration of the current state of the research is given. Different structures for the spin injection, materials and possible applications in silicon spintronics are considered and also possible future research directions are outlined.

Abstract: BaSi₂ thin films were formed on Si (111) substrate by solid-phase epitaxy (SPE) (UHV deposition) using the template technology followed by vacuum annealing at temperatures of 600 °C and 750 °C. After the deposition and annealing barium silicide films were characterized by Auger electron spectroscopy, grazing incidence x-ray diffraction (GIXRD) and atomic-force microscopy (AFM). It was established that the films annealed at T = 600 °C are polycrystalline with the structure of the orthorhombic BaSi₂, with grain sizes of 100-200 nm. Higher anneal temperature (T=750 °C) leads to increase of diffraction peak intensity of BaSi₂ phase with grain coagulation into 300-400 nm islands. It was confirmed that nanocrystalline BaSi₂ films are characterized by a direct fundamental interband transition at 1.3 eV, the second interband transition with an energy of 2.0 eV, own phonon structure with wave number peaks at 112, 119, 146 and 208 cm^-1 and a high density of defect states within the band gap, which provide a noticeable subband absorption at energies of 0.8 – 1.1 eV.

Abstract: Porous silicon layers were formed on the silicon substrates treated with compression plasma flow. Pores density and lateral size on substrates treated with plasma is by 25% more than that on untreated substrates. The intensity of the PL of the PS layers, formed on the plasma treated substrates (PT PS), is twice more than that of the PS layers, formed on untreated substrates. Three month exposure of normal PS and PT PS layers to the air leads to the PL intensity increase by 3 and 5.7 times, respectively, as well as to the peak position shifting towards long wavelength region by 3.1 nm, in the case of PT PS layer. The PL intensity increase is attributable to the reduction of the dangling bond density as a result of passivation by oxygen.