Том 45, № 10 (2019)

It has been shown that the doping of the front side of a solar cell with a deep-level p–n junction with nickel atoms increases short-circuit current density J_sc by 89% and open-circuit voltage V_oc by 19.7%. Additional thermal treatment at 700°C for 1 h increases J_sc by 98.4% and V_oc by 13.18%. It is presumed that the IR radiation conversion efficiency grows because nickel atoms form clusters, these being getter centers for uncontrolled recombinant impurities.

In this paper, we describe a portable system for measuring the indenter velocity in hardness meters implemented according to the Leeb method. The developed system is a fiber interferometer, in which a radiation source is a semiconductor laser with a wavelength of 1550 nm. The presented experimental results confirm the ability of the system to measure indenter velocities with an uncertainty of 0.001 m/s, which satisfies the requirements of the standards for this method of measuring hardness.

We studied the possibility of using composite films representing amorphous silicon reinforced with crystalline inclusions of copper silicide as an anode material for lithium-ion batteries with liquid electrolyte. The films were made by layer-by-layer magnetron sputtering of amorphous silicon and copper, followed by low-temperature (100–200°C) annealing of the structure. The tests of the anodes revealed the effect of prolonged intense growth of their reversible capacity. To describe the effect, a phenomenological model based on the multidirectional migration of silicon and copper atoms in an inhomogeneous field of elastic mechanical stresses arising during electrode cycling is proposed.

A technique for determination of the dielectric constant of individual hemoglobin molecules is presented. It is based on modeling the profiles of their images obtained using electrostatic force microscopy. The obtained values of the static dielectric constant are in agreement with the known literature data. The proposed method can be adapted to determine the dielectric characteristics of individual molecules of various proteins.

The presented experimental results demonstrate that microwave pulses of giant amplitude are generated in a klystron generator operating in the self-excited mode of chaotic oscillations. The auto-oscillator is assembled using a noisetron scheme that contains two five-cavity floating-drift klystrons serially connected in a ring, one of which operates in the mode of linear signal amplification (the linear klystron) and the other works in the mode of nonlinear signal amplification (the nonlinear klystron). It is established that, at a certain value of the beam current of a nonlinear klystron, intermittency of chaos–chaos type is realized in the auto-oscillation system in the form of chaotic sequences of microwave pulses of giant amplitude formed over the chaotic amplitude background. This type of intermittency is caused by the amplitude bistability of the nonlinear floating-drift klystron.

The results of using N-isoamylisatin 4-methylphenylhydrazone for the optimization of fullerene-based heterostructures are presented. The synthesis and microscopy of thin films of this hydrazone in combination with fullerene C₆₀ are described alongside with the results of IR spectroscopy and study of their electrophysical properties. The addition of the considered organic compound to fullerene films has increased the photoconductivity by two orders of magnitude in comparison with the photoconductivity of C₆₀ films. The synthesized thin-film structures have rectifying illumination voltage–current characteristics.

A method for analyzing the domain structure in magnetic powder microparticles based on the Mössbauer effect is proposed. This method has been experimentally verified for gadolinium ferrite-garnet (Gd₃Fe₅O₁₂) powder particles 40 ± 5 μm in diameter in the vicinity of the magnetic compensation point T_cm = 286 K. It is shown that ferrite particles are single-domain near T_cm and pass to the multidomain state while moving away from T_cm.

We consider the effect of the polarization characteristics of probe light on the signal of optically detected magnetic resonance in quantum sensors, including quantum magnetometers based on the phenomenon of electron paramagnetic resonance and quantum gyroscopes employing both the electron and nuclear magnetic resonance. Relationships between the magnetic resonance signal magnitude and parameters of the optical system elements, which are based on the Stokes–Mueller formalism, are derived and verified. It is found that the main destructive influence in the signal in a standard two-beam scheme is produced by phase delays introduced by both metallic and dielectric mirrors. Methods for compensation of this destructive influence are proposed and verified.

The influence of the localization of upper-valley electrons in a narrow-bandgap channel on the drift velocity burst in Al_xGa_{1 –x}As–GaAs transistor heterostructures with double-sided doping has been theoretically estimated. It is established that the fraction of electrons passing in this case from the narrow-bandgap channel to wide-bandgap material is smaller than in the usual structures, which can lead in some cases to an increase in the electron drift velocity by up to 15%. This phenomenon can provide an additional mechanism of current increase in transistors based on heterostructures with donor–acceptor doping.

We have studied the generation of frequency combs by quantum cascade lasers (QCLs) emitting in the 8-μm wavelength range. Results showed the presence of a self-pulsation regime near the lasing threshold. Further increase in the pumping current led to a sharp increase in width of the lasing spectrum, which allowed us to obtain frequency combs with a spectral width exceeding 1.5 THz. This behavior of QCLs can be explained by radiation absorption at the stripe edge that is related to the penetration of waveguide mode into unpumped regions.

The possible propagation of localized wave structures such as dust-acoustic solitons in dusty ionospheric plasma containing photoelectrons, electrons and ions of the ionosphere, and charged dust particles is considered. Intervals of the possible soliton velocities and amplitudes are determined. Solitary wave solutions for various dimensions and concentrations of particles in dusty ionospheric plasma are found.

A method for calculating the Debye temperature of a single-component substance in the amorphous state is proposed based on a nonlinear dependence of first coordination number k_n of the given structure on its packing factor k_p as established previously. Proceeding from previously defined parameters of the Mie–Lennard-Jones potential, the Debye temperatures have been calculated for some pure crystalline and amorphous metals, diamond, silicon, and germanium, which are in good agreement with estimations reported by other researchers. It is shown that a minimum specific Helmholtz free energy is attained at k_p = 0.45556, which means that this packing corresponds to a thermodynamically stable amorphous structure.

A new theoretical explanation of the growth of nitride nanowires (NWs) in a metastable cubic crystalline phase (sphalerite) is proposed. It is shown that the allowance for elastic stresses can explain the growth of single-crystalline nitride NWs with a cubic crystalline lattice. The possibility of growing GaN nanowires in a metastable phase on sapphire substrates is considered.

High-velocity motion of a set of supercavitating kinetic strikers during their simultaneous entry into water has been experimentally studied. A special experimental method of launching supercavitating kinetic strikers and studying their high-velocity motion under hydroballistic test setup conditions has been developed. Experimental data on the motion of two identical supercavitating strikers in the initial stage of trajectory at velocities about 1100 m/s have been obtained, which demonstrate the possibility of stable propagation of a set of such strikers in water until reaching an underwater target.