Yu. V. Medvedev

Production, identification, and use of nanocarbon in vehicles’ frictional systems

Nanocarbon production by the decomposition of hydrocarbon gas at atmospheric pressure is considered; no catalysts are employed. The role of nanocarbon in improving the antifrictional, antiwear, and antiscratch properties of lubricants is studied.

Contactless RF methods for measuring electrophysical parameters of semiconductors

We review promising contactless radio frequency (RF) methods for performing localized diagnostics on semiconductors by using quasi-stationary devices. These are resonant systems operating in the frequency range from 100 kHz to 1 GHz that feature high spatial localization of the probe electromagnetic field in small geometrical volumes of the semiconducting samples. A properly chosen operating frequency provides both high spatial resolution and good conversion transconductance for the measured parameter, the detector signal for a wide range of materials with resistivities from 10−3 to 109 Ω·cm. We discuss the design of quasi-stationary devices for multiparameter, nondestructive, contactless monitoring of semiconducting ingots, wafers, and structures. We examine methods for measuring resistivity, mobility, and free charge-carrier lifetimes in semiconductors. We describe automated systems and instruments for nondestructive, contactless measurement of parameter distribution over the surface of semiconductor wafers and structures with a spatial resolution of 1 mm. We present the technical specifications of these instruments.

Possibility of contactless measurement of free charge carrier mobility in semiconductors by the uhf resonator method

A contactless method for measuring free charge carrier mobility in semiconductors using a uhf resonator is described. The method is based on the dependence of the Q of a quasistatic uhf resonator containing the semiconductor specimen on external magnetic field induction. Simple relationships are obtained which allow low determination of the magnetoresistive mobility from the change in Q of the external portion of the resonator under the action of a weak magnetic field.

Solution of the problem of surface waves in a semiconductor chip

The problem of surface waves in a semiconductor chip is solved. Under certain conditions, there are two maxima on the curve of the damping factor for an E surface wave as a function of the resistivity of the semiconductor. The first maximum corresponds to the condition that the skin depth is equal to the thickness of the chip. The second maximum corresponds to the situation in which the period of the electromagnetic field is equal to the scale time for the relaxation to the diffusion-drift equilibrium in the semiconductor. This second maximum does not occur in the case of an H wave.

Spatial resolution of a microwave cavity method of measuring the specific resistivity of semiconductors

The problem of semiconductor polarization by the electrical field of the ring gap of a quasistatic cavity used to measure the parameters of semiconductor materials is solved. It is shown that the spatial resolution of the method is determined by the radius of the measuring orifice.

uhf Photoconductivity measurement at high excitation levels

A contactless method is described for measuring photoelectric properties of semiconductors at uhf, employing losses introduced in a resonator by photoconductivity. The possibility of experimental measurement of the filling coefficient of the working range of a uhf generator is demonstrated.

Effect of surface potential on the signal/noise ratio on a rapid-response photoresistor receiver with microwave bias

Theoretical and experimental investigations of the effect of surface potential on the response of a rapid-response photoresistor receiver with microwave bias are described. It is shown that the maximum signal/noise ratio when the threshold sensitivity is limited by circuit noise corresponds to minimum surface conductivity. The experimental results are compared with theoretical estimates.

Analysis of photoconductor receivers with microwave biasing

An expression has been derived for the threshold sensitivity of microwave-biased photoconductor receivers taking into account the detector, microwave amplifier, and video amplifier noise for different resonator connections.

Behavior of semiconductors in an SHF electric field

ConclusionsThese experimental results have shown that when an shf electric field is applied to a small semiconducting sample there is a redistribution of free carriers in the sample, which results in an increase in the carrier concentration near the sample boundaries and a decrease in the center. Carrier trapping at the sample surface has a pronounced effect on this redistribution.Since the carrier redistribution and trapping at the surface may significantly affect the characteristics of several practical devices in which small semiconducting samples are used, it is worthwhile to pursue the theoretical and experimental study of this behavior.