"Technical Physics Letters"

Gorbatyuk, A. V.

doi: 10.1134/S1063785006120017pmid: N/A

Abstract A theory describing the injection instability in high-power bipolar semiconductor switches at a current density of J ∼ 1 kA/cm2 and a collector field strength of E > 5 × 104 V/cm is proposed. It is established that, if the efficiency of cathode injection source increases with J and E, fluctuations in the current distribution over wafer area with a wavelength on the order of λ ∼ 100 μm (not related to the wafer transverse size) can develop in such devices. The corresponding volume fluctuations in the charge carrier densities, potentials, field strength, and current density are localized in the bulk, at a depth that is much smaller than the plate thickness. This latent instability is not related to the sign of the external differential resistance, so that internal damping factors are necessary in order to prevent its development.

Bodnar, I. V.;Vaĭpolin, A. A.;Rud, V. Yu.;Rud, Yu. V.

doi: 10.1134/S1063785006120029pmid: N/A

Abstract The structures of single crystals of CuIn3Se5 and CuIn5Se8 ternary compounds have been studied by X-ray diffraction for the first time. The unit cell parameters of CuIn3Se5 and CuIn5Se8 crystals are determined. It is established that CuIn3Se5 has a thiogallate lattice with c = 2a, which leads to the domain structure formation. CuIn5Se8 has a hexagonal lattice and exhibits cleavage along the (001) plane. Relationships between the atomic composition and crystal structure of these new ternary semiconductor compounds are discussed.

Fateev, E. G.

doi: 10.1134/S1063785006120030pmid: N/A

Abstract It is possible in principle that hydrogen and oxygen can evolve during the explosive instability of ice leading to its disintegration into micro-and nanofragments, which takes place under the conditions of strong nonuniform compression in the region of high pressures. The nature of the anticipated phenomenon can be related to the electron-and ion-induced sputtering and dissociation of nanodimensional ice fragments. Electrons and ions can be generated in the course of an explosive instability in ice, which is developed as a result of fractoemission, triboemission, and secondary electron emission. The yield Y of hydrogen, oxygen, and related radicals is expected to depend as Y ∝ P 2 on the threshold pressure P at which the explosive instability of ice is manifested.

Mynbaeva, M. G.;Konstantinov, O. V.;Mynbaev, K. D.;Romanov, A. E.;Sitnikova, A. A.

doi: 10.1134/S1063785006120042pmid: N/A

Abstract A decrease in the density of threading dislocations has been observed during the epitaxial growth of GaN layers on porous silicon carbide (PSC) substrates by means of chloride hydride vapor phase epitaxy. It is established that, in the early growth stage, the substrate is capable of redistributing stresses in the growing heterostructure, which leads to relaxation of the lattice misfit stresses via generation of a superlattice of planar defects. In the subsequent growth stage, these defects prevent the propagation of threading dislocations. Owing to this phenomenon, 1-μm-thick GaN layers on PSC can be obtained with a density of dislocations reduced by two orders of magnitude as compared to epilayers of the same thickness grown on nonporous substrates.

Mishagin, K. G.;Shalfeev, V. D.

doi: 10.1134/S1063785006120054pmid: N/A

Abstract The regime of synchronization with a certain gradient phase distribution and the possibility of controlling such distribution in a linear array of oscillators coupled by phase-locked loops (PLLs) have been theoretically studied. It is shown that a constant phase progression can be controlled by manipulating collective dynamics, with oscillator eigenfrequencies and coupling coefficients being the control parameters. The proposed principle of control, based on the nonlinear dynamics of PLL-coupled oscillators, can be used in solving the problems of phasing and controlled beam scanning in antenna arrays operating in different frequency bands.

Vintizenko, I. I.;Zarevich, A. I.;Novikov, S. S.

doi: 10.1134/S1063785006120066pmid: N/A

Abstract The spectral characteristics of a relativistic microwave magnetron with cavities coupled via an external waveguide channel have been experimentally studied. It is shown that the output microwave radiation with a stable narrow spectrum and improved energy characteristics can be obtained with properly adjusted coupling in the system.

Ryabkov, O. V.;Petrov, V. M.;Bichurin, M. I.;Srinivasan, G.

doi: 10.1134/S1063785006120078pmid: N/A

Abstract The magnetoelectric (ME) effect in ferrite-piezoelectric bilayers has been theoretically studied at coinciding frequencies of the electromechanical resonance in the electric subsystem and ferromagnetic resonance in tangentially magnetized ferrite. Giant values of the ME voltage coefficient (50–70 V/A at 5 GHz) are predicted for the YIG-PZT system. In contrast to the case of a normally magnetized plate, the magnetoacoustic resonance in a tangentially magnetized sample takes place at a lower value of the magnetic bias field and a smaller ferrite layer thickness. This effect can be used for the development of multifunctional ME nanosensors and transducers operating in the microwave range.

Goloudina, S. I.;Luchinin, V. V.;Rozanov, V. V.;Pasyuta, V. M.;Sklizkova, V. P.;Kudryavtsev, V. V.

doi: 10.1134/S106378500612008Xpmid: N/A

Abstract The surface structure of a three-layer Langmuir-Blodgett film of comblike rigid-chain polyimide prepolymer (polyamic acid alkylammonium salt) has been studied by atomic force microscopy (AFM). The AFM data reveal the presence of supramolecular formations consisting of two-dimensional domains in which aliphatic chains of the prepolymer macromolecules are oriented perpendicularly to the substrate. A mechanism responsible for the supramolecular structure formation in the film is proposed.

Zubarev, N. M.;Zubareva, O. V.

doi: 10.1134/S1063785006120091pmid: N/A

Abstract It is shown that the problem of determining the profile of an electrocapillary wave on the surface of the ideal dielectric liquid in a tangential electric field admits exact solution in the limiting case of a large permittivity of the liquid. An exact expression for the nonlinear dispersion relation between the frequency, wavenumber, and amplitude of the wave is obtained and analyzed.

Nevolin, V. K.

doi: 10.1134/S1063785006120108pmid: N/A

Abstract It is demonstrated that, during field electron emission from the cathode, the amount of heat evolved in the anode can differ from the classical value, provided that the translational energy of electrons reaching the anode does not exceed the Fermi energies of electrons in the dissimilar electrode pair. This effect is related to the fact that each electron emitted from the cathode brings the corresponding Fermi energy to the anode, in addition to the energy of the applied field. Therefore, under-or overheating of the anode is possible due to a difference between the Fermi energies.