V. I. Perel

Spin-dependent tunnelling through a symmetric barrier

The problem of electron tunneling through a symmetric semiconductor barrier based on zinc-blende-structure material is studied. The k3 Dresselhaus terms in the effective Hamiltonian of bulk semiconductor of the barrier are shown to result in a dependence of the tunneling transmission on the spin orientation. The difference of the transmission probabilities for opposite spin orientations can achieve several percents for the reasonable width of the barriers.

Effect of a magnetic field on thermally activated tunneling ionization of impurity centers in semiconductors

An expression for the probability of thermally activated tunneling ionization in an electric field in the presence of a magnetic field is obtained. It is shown that the logarithm of the ionization probability is proportional to the squared electric field, and the coefficient of proportionality decreases with increasing magnetic field.

Effect of a magnetic field on thermally stimulated ionization of impurity centers in semiconductors by submillimeter radiation

The probability of electron tunneling from a bound state into a free state in crossed ac electric and dc magnetic fields is calculated in the quasiclassical approximation. It is shown that a magnetic field decreases the electron tunneling probability. This decreases the probability of thermally activated ionization of deep impurity centers by submillimeter radiation. The logarithm of the ionization probability is a linear function of the squared amplitude of the electric field and increases rapidly with the frequency of the electric field.

Magnetic field effect on tunnel ionization of deep impurities by far-infrared radiation

The probability of electron tunneling from a bound to a free state in an alternating electric and a constant magnetic field is calculated in the quasiclassical approximation. It is shown that the magnetic field reduces the probability of electron tunneling. The application of the external magnetic field perpendicular to the electric field reduces the ionization probability at high magnetic fields, when cyclotron resonance frequency becomes larger than reciprocal tunneling time. The increase of electric field frequency to values larger than the same reciprocal tunneling time enhances the influence of magnetic field.

Cascade theory of electron capture in quantum wells

A cascade theory of electron capture in shallow quantum wells, when the capture process is determined by the interaction with acoustic phonons, is constructed. In these conditions, the ejection of electrons falling into a well back to the conduction band is significant. The possibility of electron ejection is taken into account by introducing an sticking probability for electrons located in the well. Such an approach is analogous to the Lax cascade theory of electron capture at small impurity centers. Calculations have been performed for wells 3 and 4 nm in width in the Al0.05Ga0.95As/GaAs/Al0.05Ga0.95As heterostructure. The developed theory has also made it possible to describe thermal ejection of electrons from shallow quantum wells.

Scattering of hot electrons by neutral acceptors in GaAs/AlAs quantum well structures

The optical alignment of hot electrons and its destruction in a magnetic field under conditions when electron scattering by neutral acceptors plays a large role is investigated. This makes it possible to determine the probability of the scattering of hot electrons from an initial photoexcited state, as well as the times characterizing the energy and momentum relaxation of hot electrons on scattering by neutral acceptors. The experimental results are compared with calculations.

Giant negative magnetoresistance in semiconductors doped by multiply charged deep impurities

A giant negative magnetoresistance has been observed in bulk germanium doped with multiply charged deep impurities. Applying a magnetic field the resistance may decrease exponentially at any orientation of the field. A drop of the resistance as much as about 10 000% has been measured at 6 T. The effect is attributed to the spin splitting of impurity ground state with a very large g factor in the order of several tens depending on impurity.

Inelastic hot electron scattering by neutral acceptors in GaAsAlAs multiple quantum well structures

Abstract We have studied inelastic hot electron scattering due to interaction with neutral acceptors accompanied by their excitation and ionization. Comparative studies of narrow GaAs AlAs multiple quantum wells and bulk GaAs films were performed in the concentration range of neutral acceptors 1018–1019 cm−3. The method of hot photoluminescence depolarization in an applied magnetic field was utilized. The scattering cross-section in multiple quantum wells was shown to be four times smaller than in the bulk samples. A theoretical model of hot electron scattering by acceptors in a quantum well is developed that explains satisfactorily the experimental results.

Polarization of hot photoluminescence in GaAs/AlAs superlattices

The polarization characteristics of hot photoluminescence in GaAs/AlAs superlattices are investigated experimentally and theoretically. It is shown that the formation of an electronic miniband in the superlattice substantially changes the polarization characteristics of the photoluminescence. As a result of the quasi-three-dimensional character of the motion of hot electrons in the superlattice, the polarization depends on the ratio of the electron kinetic energies in the plane of the superlattice and along the axis of the superlattice.

Characterization of deep impurities in semiconductors by terahertz tunneling ionization

Abstract Tunneling ionization in high-frequency fields as well as in static fields is suggested as a method for the characterization of deep impurities in semiconductors. It is shown that an analysis of the field and temperature dependences of the ionization probability allows to obtain defect parameters like the charge of the impurity, tunneling times, the Huang–Rhys parameter, the difference between optical and thermal binding energy and the basic structure of the defect adiabatic potentials. Compared to static fields, high-frequency electric fields in the terahertz-range offer various advantages, as they can be applied contactlessly and homogeneously even to bulk samples using the intense radiation of a high-power pulsed far-infrared laser.