Том 50, № 13 (2016)

The mechanisms of gallium nitride crystallization during vapor phase epitaxy are theoretically analyzed. The limited growth in the boundary layer is thoroughly investigated. The conditions for control of the process and intensification of the mass transfer are determined. The effect of the substrate rotation speed on the crystallization mechanism is experimentally studied.

Two methods of accounting for the inclusion-shape randomness, an analytical method and a method for simulating a medium with several inclusion types, are considered for calculating the effective permittivity tensor of a textured heterogeneous matrix-type medium with inclusions of a random ellipsoidal shape. The methods are based on the generalized Maxwell–Garnett model. The rotation group representations are used to consider the distribution of inclusion orientations. The results of calculations by these methods of the effective dielectric characteristics of porous silicon models in an alternating electromagnetic field in the frequency range of 10₃–10₈ Hz are compared.

The specific features of fabrication of 3D silicon structures via local formation of a sacrificial porous silicon layer by metal-assisted chemical etching with 50- and 100-nm-thick silver films as a catalyst are studied. It is found that the mass transfer of Ag⁺ ions, caused by the temperature gradient, affects the surface morphology of the structure being formed, depending on the linear size of the mask-catalyst.

Methods for suppressing optical crosstalk between cells in silicon photomultipliers were experimentally studied. The mechanisms of optical crosstalk suppression are considered and the extent of the effect of each type is shown. A method for separating photosensitive cells, based on etching of V-shaped grooves is studied. The principal possibility of decreasing optical crosstalk between cells from 20−40 to 0.1−0.7% is shown in the overvoltage range of 2−5 V, respectively.

The process of oxidation of single-layer and multilayer graphene films upon ultraviolet irradiation of the structure in water vapor was studied. The systematic features and distinctions between changes in the topographic and optical properties of graphene films composed of different numbers of layers were established. The possibility of surface functionalization accompanied by modification of the energy structure of graphene was shown. Differences between single-layer and multilayer graphene films in the mechanisms of oxidation on ultraviolet irradiation are discussed and analyzed. Correlation of the topographic imperfections of the properties of the graphene material with its structural defects observed in Raman spectra was shown.

It is shown that it is possible to grow carbon nanotubes on the surface of an amorphous Ni–Ta–N metal alloy film with a low Ni content (~25 at %) by chemical deposition from acetylene at temperature 400–800°C. It is established that the addition of nitrogen into the Ni–Ta alloy composition is favorable for the formation of tantalum nitride and the expulsion of Ni clusters, which act as a catalyst of the growth of carbon nanotubes, onto the surface. From Raman spectroscopy studies, it is found that, as the temperature of synthesis is raised, the quality of nanotubes is improved.

The results of electron microscopy studies of an epitaxial InAlAs layer on a GaAs(100) substrate are reported. It is established that there exist misfit dislocations at the interface between the materials and there are residual strains distorting the lattice in the layer. From the measurements of lattice parameters in the directions parallel and orthogonal to the growth direction away from misfit dislocations, the local nominal lattice parameter of the layer is calculated and the relative content of indium is determined.