Lev Smirnov

The model of self-compensation and pinning of the Fermi level in irradiated semiconductors

A model is developed to analyze numerically the electrical properties and the steady-state (limiting) position of the Fermi level (Flim) in tetrahedral semiconductors irradiated with high-energy particles. It is shown that an irradiated semiconductor represents a highly compensated material, in which Flim is identical to 〈EG〉/2, where 〈EG〉 is the average energy gap between the conduction band and valence band within the entire Brillouin zone of the crystal. The experimental values of Flim, the calculated values of 〈EG〉/2, and the data on the electrical properties of irradiated semiconductors are presented. The chemical trends controlling the variation in the quantity Flim in groups of semiconductors with the similar types of chemical bonding are analyzed.

Chimera patterns in the Kuramoto–Battogtokh model

Kuramoto and Battogtokh [Nonlinear Phenom. Complex Syst. 5, 380 (2002)] discovered chimera states represented by stable coexisting synchrony and asynchrony domains in a lattice of coupled oscillators. After reformulation in terms of local order parameter, the problem can be reduced to partial differential equations. We find uniformly rotating periodic in space chimera patterns as solutions of a reversible ordinary differential equation, and demonstrate a plethora of such states. In the limit of neutral coupling they reduce to analytical solutions in form of one- and two-point chimera patterns as well as localized chimera solitons. Patterns at weakly attracting coupling are characterized by virtue of a perturbative approach. Stability analysis reveals that only simplest chimeras with one synchronous region are stable.

Atomic processes in semiconductor crystals

The formation of a new field in the radiation physics of semiconductors and semiconductor technology under the general guidance and with the direct participation of the late A. V. Rzhanov is reviewed historically. This line of research gave rise to a multitude of practical applications; however, most importantly, it forced scientists to radically change the established concepts of reactions in semiconductor crystals by taking into account the mobile defect-impurity subsystem susceptible to external factors. The concepts developed form the basis for considering the processes at the atomic level, especially during the formation and modification of active clusters and nanoobjects.

Simple and complex chimera states in a nonlinearly coupled oscillatory medium

We consider chimera states in a one-dimensional medium of nonlinear nonlocally coupled phase oscillators. In terms of a local coarse-grained complex order parameter, the problem of finding stationary rotating nonhomogeneous solutions reduces to a third-order ordinary differential equation. This allows finding chimera-type and other inhomogeneous states as periodic orbits of this equation. Stability calculations reveal that only some of these states are stable. We demonstrate that an oscillatory instability leads to a breathing chimera, for which the synchronous domain splits into subdomains with different mean frequencies. Further development of instability leads to turbulent chimeras.

Nature of E c −0.37 eV centers and the formation of high-resistivity layers in n-type silicon

The DLTS and Van der Pauw methods are used to investigate the production of Ec−0.37 eV centers responsible for the formation of high-resistivity layers in n-type Si irradiated with electrons and annealed in the temperature range 80–320 °C. An analysis of the experimental data leads to a conclusion as to the composition of the Ec−0.37 eV centers ([V-O-C]) and to the conclusion that their formation is stimulated by a flux of interstitial atoms away from the interface into the interior of the semiconductor during annealing accompanied by the reactions: 1) I+Cs→Ci,Ci+[V-O]→[V-O-C] (dominant reaction); 2) I+V2→V,V+[C-O]→[V-O-C].

Changes in the state of phosphorus atoms in the silicon lattice as a result of interaction with radiation defects

Interaction of radiation defects with phosphorus atoms in silicon crystals subjected to electron irradiation and thermal treatments was studied under conditions of various degrees of supersaturation with respect to the equilibrium concentration of impurities and point defects. It is shown that, in the course of silicon irradiation, the electron-dose dependences of the phosphorus concentration at the lattice sites (Ps) level off (tend toward a constant value). This constant value is governed by the irradiation temperature. The stages of recovery of the concentration Ps as a result of heat treatments correlate with temperature intervals of dissociation of the vacancy complexes. The results indicate that there are two processes. One process involves the interaction of dopant atoms with silicon self-interstitials and the emergence of interstitial complexes; i.e., this process corresponds to the radiation-stimulated decomposition of a supersaturated solution of an impurity as a result of point-defect generation and ionization. The other process consists in the recombination of interstitial impurities with vacancies at sufficiently high temperatures or in the annihilation of vacancies released during heat treatments with interstitial atoms incorporated into composite defect complexes with the involvement of phosphorus atoms.