A. S. Kovalev

Effect of transverse magnetic field on the behavior of longitudinal autosolitons in p-InSb

The behavior of a longitudinal autosolitons created in excited nonequilibrium electron-hole plasma in compensated p-InSb in crossed magnetic and electric fields is studied experimentally. It is shown that, in magnetic fields ranging from 6.7 × 102 to 3.2 × 104 A/m, a longitudinal autosoliton is in a state of motion with the average velocity 2 × 102−3 × 103 cm/s towards the sample periphery, where the temperature is reduced and the autosoliton is unstable, making the process cyclic and giving rise to oscillations of the current in the external circuit of the sample. In this case, the amplitude and frequency of the oscillations (2144-26855 Hz) depend on the magnetic field. With increasing electric and magnetic fields, the instability of the longitudinal autosoliton current takes on synergetic properties.

Distribution of charge carriers in dissipative semiconductor structures

It was experimentally shown that redistribution of the charge-carrier concentration occurred in nonequilibrium electron-hole plasma during formation and excitation of the dissipative structure by a strong electric field in the bulk of Te and InSb single crystals. In this case, if there are only longitudinal autosolitons in the dissipative structure, the carrier concentration decreases outside the autosolitons. The charge-carrier concentration increases outside autosolitons if the transverse autosolitons are present. It is suggested that the longitudinal autosolitons formed in the nonequilibrium electron-hole plasma developed by the Joule heating are “cold” and the transverse autosolitons are “hot”.

Fission of longitudinal autosolitons in InSb in a magnetic field

The behavior of longitudinal autosolitons in InSb in a weak magnetic field was studied. It is shown experimentally that a weak longitudinal magnetic field affects significantly the behavior of longitudinal autosoliton in InSb samples. In all samples, sharp changes in the current due to fission of longitudinal autosoliton were observed for certain values of a magnetic field. It was found that the magnitude of initial autosoliton cur-rent took a different stable value under the effect of a magnetic field. The initial value of the autosoliton current is recovered if a magnetic field of opposite orientation is applied to the sample.

On the resonant donor level in n-CdTe according to data on electron transport under hydrostatic pressure

Results of quantitative analysis of experimental data on baric (under the hydrostatic pressure to P = 2.5 GPa and T = 300 K) and temperature (in the temperature range of 15–300 K at atmospheric pressure) dependences of the Hall coefficient and electrical conductivity of bulk n-CdTe crystals with the electron concentration of 1015–1017 cm−3 at T = 300 K are presented. The four-level model is used and included deep donor levels arranged in the band gap and in the continuous spectrum of the conduction band and shallow donor and acceptor levels. The location of the donor levels and pressure coefficients of energy gaps between them and the edge of the conduction band are determined.

Longitudinal autosoliton motion across p-InSb in a transverse magnetic field

It is experimentally shown that a longitudinal autosoliton excited by an electric field in nonequilibrium electron-hole plasma in p-InSb moves towards the sample periphery under the effect of a transverse magnetic field. This sample region is characterized by a lowered temperature and by the fact that the unstable existence of the autosoliton leads to a cyclic process causing current oscillations in the sample circuit. An average velocity of the autosoliton motion amounts to 2 × 102−3 × 103 cm/s in a magnetic field within the range of 5962.5–22657.5 A/m.

Autosolitons in InSb in a magnetic field

It is shown experimentally that a longitudinal magnetic field of comparatively small magnitude substantially changes the velocity of autosolitons in indium antimonide samples and produces an appreciable redistribution of the electric field of these autosolitons. In this case, the frequency and amplitude of the current oscillations in the external circuit of the sample increases or decreases, depending on the direction of the longitudinal magnetic field.

Autosolitons in InSb in a low magnetic field

It is shown experimentally that a relatively low applied longitudinal magnetic field causes a noticeable change in the velocity of autosoliton travel in InSb samples and a redistribution of these autosolitons in the electric field. As a result, the current oscillation frequency and amplitude in the external circuit of the sample either increase or decrease depending on direction of the magnetic field.

Localization of a longitudinal autosoliton in InSb

The current density distribution over the cross section of a sample was studied to localize a longitudinal autosoliton in the sample. It is shown that the longitudinal autosoliton is localized along the central axis of the sample or close to it. It is established that the longitudinal autosoliton is stable in a wide range of currents.

Phenomena of the collective behavior of autosolitons in a dissipative structure in InSb

It is shown that the behavior of autosolitons can be considered as the behavior of an ensemble of interacting solitary localized states in the electron-hole plasma. Investigations revealed transitions from the modes of chaotic oscillations of a current in the external circuit of a sample, which are caused by the motion of autosolitons, to regular oscillations, and from regular oscillations to other regular oscillations through bifurcation by doubling the period with increasing the excitation level of the electron-hole plasma. It is concluded that the system which consists of an ensemble of interacting autosolitons possesses the property of self-organization. It is shown that the autosolitons, which travel through the sample in an external longitudinal magnetic field as strong as 13.6×103 A/m, also exhibit synergetic behavior in a dissipative structure in InSb.

Autosolitons in electron-hole plasma in InSb under hydrostatic pressure

The rise in resistance and the initially growing threshold voltage of longitudinal autosoliton formation in p-InSbCr crystals subjected to high pressure result from an increase in the energy gap width and decrease in carrier concentration with increasing pressure. The subsequent decrease in the threshold voltage is due to falling carrier mobility and growing energy spacing between the deep acceptor level and the conduction band bottom. The regularity of the current oscillations associated with the motion of transversal autosolitons along the sample is disturbed. With increasing pressure, the oscillations become chaotic and the number of oscillation modes decreases.