卷 50, 编号 13 (2016)
- 年: 2016
- 文章: 13
- URL: https://journals.rcsi.science/1063-7826/issue/view/12438
Materials for Electronic Engineering
Improving the functional characteristics of gallium nitride during vapor phase epitaxy
摘要
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.
Interaction of electromagnetic radiation with magnetically functionalized CNT nanocomposite in the subterahertz frequency range
摘要
The interaction of electromagnetic radiation with a magnetically functionalized nanocomposite based on carbon nanotubes (CNTs) is considered using the model of random distribution of ferromagnetic nanoparticles in the carbon matrix characterized by the presence of resistive–inductive–capacitive coupling (contours). The model is based on the representation of the nanocomposite as a system consisting of the CNT matrix, ferromagnetic nanoparticles, and the interfaces between CNTs and nanoparticles. The wide range of possible resonant phenomena caused both by the presence of contours and the properties of the CNT nanocomposite is shown.
Methods of accounting for inclusion-shape randomness in calculating the effective dielectric characteristics of heterogeneous textured materials
摘要
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.
Method of investigation of galvanomagnetic properties of CdxHg1 − xTe and CdxHg1 − xTe/Cd1 − yZnyTe
摘要
The galvanomagnetic Van der Pau measurements are carried out on single-crystalline CdxHg1−xTe (MCT) bulk samples and CdxHg1 − xTe/Cd1 − yZnyTe (MCT/CZT) (x ≈ 0.2) epitaxial heterostructures at the temperature of 295 and 77 K. The sample rotates together with the cryostat in the electromagnet field through the angle from 0° to 360° with the step of 6°. It is shown that the angular dependences of the voltage under measurement are sinusoidal for the p-MCT bulk sample at the temperatures of 77 K; i.e., the Hall coefficient is independent of the magnetic-field induction. However, the angular dependences of the measured signal appreciably differ from sinusoids for the MCT/CZT epitaxial heterostructures at the temperature of 77 K.
Microelectronic and Nanoelectronic Technology
Effect of ionic Ag+ transfer on localization of metal-assisted etching of silicon surface
摘要
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.
Formation of field-emission emitters by microwave plasma-chemical synthesis of nanocarbon structures
摘要
A nanocarbon-emitter technology for integrated field-emission elements has been developed. The modes in which various carbon film structures of diamond, graphite, and graphene-like types are produced were determined. The low-temperature method of obtaining ultradispersed diamonds was examined. It is shown that the high-emission properties of nanodiamond-graphite emitters result from the self-organization of diamond nanocrystals in a graphite film in the course of deposition from ethanol vapor at low pressure with the use of a strongly nonequilibrium microwave plasma. The following parameters of integrated field-emission diodes were obtained: emission threshold of 2.5 V/μm and emission current density of 1.75 A/cm2. The highest current density of more than 20 A/cm2 was obtained in a study of blade-type emitters.
Microelectronic Devices and Systems
Methods for suppressing optical crosstalk between the cells of a silicon photomultiplier array
摘要
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 effect of the electron–phonon interaction on reverse currents of GaAs-based p–n junctions
摘要
An algorithm for calculating the parameters of the electron–phonon interaction of the EL2 trap has been developed and implemented based on the example of GaAs. Using the obtained parameters, the field dependences of the probabilities of nonradiative transitions from the trap and reverse currents of the GaAs p–n junctions are calculated, which are in good agreement with the experimental data.
Nanotechnology
Surface functionalization of single-layer and multilayer graphene upon ultraviolet irradiation
摘要
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.
Nanostructured current sources based on carbon nanotubes excited by β radiation
摘要
An analysis of available and promising developments is carried out in the field of power elements based on β decay. The possible fabrication technologies are described, and the efficiency of the power sources manufactured with them is calculated. The possibility of designing a self-charging supercapacitor based on carbon nanotubes is considered with the use of 63Ni and 14C isotopes, and theoretical calculation confirms the promising nature of this line of research.
Formation of carbon nanotubes on an amorphous Ni25Ta58N17 alloy film by chemical vapor deposition
摘要
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.
Methods and Technique of Measurements
Study of the structure and composition of the strained epitaxial layer in the InAlAs/GaAs(100) heterostructure by transmission electron microscopy
摘要
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.
Measurements of electrophysical characteristics of semiconductor structures with the use of microwave photonic crystals
摘要
A method is proposed for the measurement of the electrophysical characteristics of semiconductor structures: the electrical conductivity of the n layer, which plays the role of substrate for a semiconductor structure, and the thickness and electrical conductivity of the strongly doped epitaxial n+ layer. The method is based on the use of a one-dimensional microwave photonic crystal with a violation of periodicity containing the semiconductor structure under investigation. The characteristics of epitaxial gallium-arsenide structures consisting of an epitaxial layer and the semi-insulating substrate measured by this method are presented.