Technical Physics Letters

In this paper, we propose and study a model of a source of ultra-wideband chaotic oscillations of the 30–50 GHz range in an IC version based on a 130-nm silicon-germanium technology.

It is demonstrated that microdisk lasers about 10 μm in diameter with an active region based on InAs/InGaAs quantum dots synthesized on GaAs substrates can be used for biodetection. Chimeric monoclonal antibodies against the CD20 protein that are covalently attached to the surface of microdisk lasers operating in an aqueous medium under optical pumping and room temperature were used as detectable objects. It is shown that the addition of secondary antibodies leads to an increase in the threshold power of laser generation, as well as to an increase in the full width at half maximum (FWHM) of the resonance laser line.

Binary interatomic potentials F–F, F–Si, F–O, F–C, and F–H are calculated from the first principles (ab initio) on the basis of the multi-configuration method of self-consistent field (CAS-SCF) with a basic set of atomic wave functions aug-pp-AV6Z and are used to calculate phase shifts and cross sections of elastic scattering of atoms in the range of relative kinetic energies of 2–200 eV. It is expected that the obtained elastic scattering cross sections will be useful for a description of sputtering and etching of porous organosilicate films with ethylene bridges used in modern nanoelectronics.

An experimental and numerical approach for studying the bubble deformation on the surface in the shear flow of viscous liquid is developed. The numerical approach is based on the boundary element method for the Stokes flows. The methods of optical microscopy and high-speed recording are applied for the experimental investigation of the bubble deformation. The dynamics of the variation in the receding and advancing contact angles is studied in dependence on the intensity of the shear flow of viscous liquid. A qualitative and quantitative agreement between the numerical modeling and experimental results for various capillary numbers is obtained.

A strong dependence of the optical breakdown in a liquid in the ultrasonic field on the amplitude and frequency of ultrasound is demonstrated. The increase in the intensity of spectral lines of potassium and oxygen during the optical breakdown is detected by the increase in the amplitude and frequency of ultrasound. At the same time, the effect of saturation is observed at high frequencies (above 200 kHz) and for high ultrasonic powers, when the growth in the intensity of spectral lines slows sharply down. This shows that there is no necessity to use high powers and frequencies of ultrasound to study the opto-acoustic effects during optical breakdown in a liquid.

The possibility of generating ultrabroadband chaotic oscillations within a frequency range up to 60 GHz with a bipolar SiGe heterojunction transistor is demonstrated. The uppermost frequency of this range is determined by the cutoff frequency of the active generator element. Such a possibility appears after the generator structure is complemented with an additional nonlinear circuit, in which chaotic oscillations can be developed up to the aforementioned frequency. Some results of the experimental study of one generator configuration based on lumped elements are presented.

Efficiency of the transmission of high-frequency signals by semiconductor plasma antennas based on Ge and Si single crystals with surface nonequilibrium electron-hole plasma generated by laser diode radiation has been experimentally studied. Dependences of the amplitude of a radiated 6- to 7.5-GHz microwave signal on the laser power and size of the laser-irradiated region on the semiconductor transmitting dipole antenna are determined. It is shown that a more than tenfold increase can be achieved in the efficiency of useful signal transmission by the plasma antenna formed in Ge crystals.

The postgrowth processing of mesa structures for multijunction solar cells based on GaInP/GaInAs/Ge heterostructure has been studied. Methods of wet chemical and electrochemical etching are considered, and a technology of forming a separation mesa structure is proposed that ensures improved surface quality and profile of the side wall of a mesa for heterostructures with various compositions of layers.

Thin aluminum nitride (AlN) films on sapphire (Al₂O₃) substrates were grown by means of ion-beam deposition (IBD) and studied by methods of scanning electron microscopy, Raman scattering, and optical transmission spectroscopy. Results revealed the influence of IBD process parameters (gas mixture composition, ion beam energy, and substrate temperature) on the morphology, structure, and optical properties of obtained thin AlN films on sapphire.

The dependence of random telegraph noise (RTN) amplitude on the gate overdrive in a junctionless field-effect transistor (FinFET) with rectangular and trapezoidal channel (fin) cross sections manufactured using silicon-on-insulator technology has been numerically simulated. It is established that the RTN amplitude in the subthreshold region of gate voltages for a FinFET with a trapezoidal cross section of channel is significantly lower than that for the transistor with rectangular cross section of a channel. In addition, under the same conditions, the RTN amplitude at the threshold gate voltage in a junctionless FinFET is significantly lower than that in planar fully depleted and in usual FinFET.

We report on the method and results of a mass-spectrometric investigation of the yield of positive ions formed as a result of the dissociative ionization of glutamic acid and glutamine by electron impact in the gas phase. The measurements were performed at various temperatures using a monopole mass spectrometer of MX-7304A type in a range of ion masses within 10–150 Da. Peculiarities of the formation of molecular fragment ions of glutamic acid and glutamine by electron impact were studied in detail and the dynamics of fragment ion yield was measured at various temperatures of evaporation of the initial substances within 310–430 K.

Parameters of terahertz (THz) emission in two-dimensional (2D) tungsten diselenide (WSe₂) film grown by chemical vapor deposition from the gas phase have been studied for the first time. The main mechanism of THz radiation generation in this system is established. Dependence of the THz signal amplitude on azimuthal angle in a 2D WSe₂ film has been studied. The distribution of the electric field of laser pumping in the WSe₂/SiO₂/Si structure has been calculated as dependent on the thickness of silicon dioxide layer. The choice of optimum structure geometry for effective generation of THz radiation by a WSe₂ monolayer is theoretically substantiated.

Electrical characteristics of atmospheric-pressure glow discharge at constant currents up to 40 mA in flows of atomic and molecular gases have been measured at volume flow rates varied within 0.5–5 L/min. It was found that the voltage drop on the discharge gap in molecular gases depends not only on the flow rate, but also on the polarity of applied voltage. As the gas flow rate increases, the discharge operation in oxygen and nitrogen becomes unstable and the voltage drop on discharge gap increases by several hundred volts. Both these effects are manifested much more strongly for a positive discharge voltage than for the negative voltage. In helium and argon flowing at a preset rate, the voltage polarity on electrodes does not influence the regime of discharge operation.