An. V. Skripal

Determination of the metal nanometer layer thickness and semiconductor conductivity in metal-semiconductor structures from electromagnetic reflection and transmission spectra

Interaction of electromagnetic radiation with metal-semiconductor nanometer structures is studied theoretically and experimentally. A technique for nondestructive multiparametric control of the electrophysical parameters of metal nanometer layers and semiconductor conductivity in metal-semiconductor structures using electromagnetic reflection and transmission spectra is proposed and tested experimentally.

Nanometer vibrations measured using a semiconductor laser on quantum-confined structures operating in an autodyne regime

A method for the quantitative monitoring of nanometer vibrations has been developed based on the autodyne detection effect in a semiconductor laser. It is shown that the semiconductor laser autodyne can be used for measuring the amplitudes of vibrations in a range from one nanometer to 10 μm in a frequency band from a few hertz to several hundred megahertz. With the aid of a lock-in amplifier, the lower threshold of measured vibration amplitudes has been reduced to one ångström.

Appearance of S-shaped sections on the current-voltage characteristics of p-n junction diodes exposed to microwave radiation

An experimental investigation was made of the influence of microwave irradiation on the low-frequency current-voltage characteristics of p-n junction diodes. It is shown that when the microwave power increases to a certain level, a clearly defined S-shaped section appears on the current-voltage characteristic of the diode. This section becomes broader as the microwave signal increases further and then disappears when the microwave irradiation ceases.

Conditions for negative differential resistance and switching in a tunnel diode under the effect of an external microwave signal

Experimentally observed phenomenon of the origination of the mode of negative differential resistance and switching in a tunnel diode under the effect of external microwave signal is theoretically interpreted. The reasons for the existence of the ranges of bias voltages applied to the diode and the power levels of microwave signal for which the phenomenon is observed are clarified.

Appearance of negative resistance in p-n junction structures in a microwave field

The results of theoretical and experimental investigations of the appearance of negative differential resistance in p-n junction diode structures in the presence of a high level of microwave power are presented. The theoretical analysis of the influence of a high level of microwave power on the form of the current-voltage characteristic of a diode takes into account the variation of the constant component of the current flowing through the p-n structure due to the heating of the free charge carriers and the rectifier effect.

Determining acceleration from micro- and nanodisplacements measured using autodyne signal of semiconductor laser on quantum-confined structures

The possibility of using a semiconductor laser for measuring the constant acceleration of an external reflector on micro- and nanodisplacement scales. It is shown that the range of measurable accelerations can be shifted toward smaller values. The minimum measured constant acceleration value was 20 nm/s2. Using the proposed technique, it is possible to determine constant accelerations in various parts of the trajectory and follow temporal variation of this parameter.

Frequency dependence of the coefficient of microwave radiation reflection from magnetic fluid at liquid nitrogen temperatures

The coefficient of microwave radiation reflection from a plane layer of a magnetic fluid magnetized by a magnetic field of 11.5 kOe is measured in the temperature range 253–293 K. The concentration of the magnetic phase (magnetite) is 15 vol %. In this temperature range, the dynamic susceptibility of nanoparticles exhibits strong dispersion (ferromagnetic resonance). Experimental data are treated by invoking the theory of high-frequency magnetization of an ensemble of interacting isotropic superparamagnetic particles. It is shown that, when the temperature drops below the room value, the trends observed at elevated temperatures (a decrease in the fraction of the power reflected from the magnetic fluid and an increase in the frequency of a minimum in the frequency dependence of the power) are retained.

Temperature Dependence of the Coefficient of Reflection of Microwave Radiation from a Magnetic Fluid Layer

The coefficient of reflection of microwave radiation from a plane layer of a magnetic fluid magnetized in a field of 11.5 Oe is measured in a frequency range of 24 MHz in temperature intervals 293–333 K; the volume concentration of the magnetic phase (magnetite) is 15 vol %. In this range, the dynamic susceptibility of nanoparticles exhibits strong dispersion (ferromagnetic resonance). The experimental results are interpreted on the basis of the theory of high-frequency magnetization for an ensemble of noninteracting isotropic super-paramagnetic particles. It is found that this simple model provides a satisfactory description of the temperature and frequency dependences of the reflection coefficient.

Determination of the magnetic fluid parameters from the microwave radiation reflection coefficients

The interaction of microwave radiation with a magnetic fluid that completely fills a waveguide and is bounded by a dielectric insertion is studied at frequencies between 20 and 40 GHz. The frequency dependence of the alternating interference maxima and minima that are associated with the reflection from the front and back walls of the dielectric insertion is found. The reason for such a dependence is the variation of the complex magnetic susceptibility of the magnetic fluid. The inverse problem, i.e., the determination of the ferromagnetic particle diameter and the volume content of the solid phase in the magnetic fluid, is solved based on the frequency dependence of the reflection coefficient.

Diffraction of light by agglomerates in a layer of magnetic fluid situated in a magnetic field parallel to the plane of the layer

Previously unknown behavior observed when laser radiation propagates through a layer of magnetic fluid with and without an external magnetic field are established for the first time and their physical nature is explained.