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Areas of scientific research Areas of basic theoretical research: 1) The electronic states in semiconductor nanostructures 2) The scattering of electrons by phonons 3) Tunneling of electrons in the barrier heterostructures 4) Deep levels in semiconductors
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Some results of research: 1) The appearance of zero in the coefficient of transmission of electrons through heteroboundary GaAs/AlAs (001) caused by the mutual compensation of deposits from the "virtual processes" involving Г1, X1 and X3 states. This feature is not associated with any interface resonant states, as a consequence of the nature of the band spectrum manyvalley GaAs, AlAs. 2) Deep level states in the superlattice (GaAs)n(AlAs)m depend on the position in the lattice defects. Lowering of the symmetry in comparison with binary crystals leads to a partial (or complete) removal of the degeneracy of deep levels of vacancies are in secondary (outer) with respect to the Al layer, as well as to the different orientations of their charge densities. The greatest changes there are vacancies for As, located directly at the interface. 3) The results of multiband calculations electronic structure of GaN/Ga1-xAlxN (0001) satisfactorily described by the method of the envelope of the wave function, taking into account dependence of the effective mass of energy and deformation. The spontaneous and piezoelectric polarizations lead to the red or blue shift of the resonance energies depending on the thickness and location of barriers with respect to the polar axis. In superlattices (GaN)n(Ga1-xAlxN)m internal field can form a Stark ladder of electron states with a small number of ultra-thin layers, even in the absence of an external field. 4) Localized electronic states of gallium arsenide with arsenic clusters can be interpreted as the result of splitting due to interaction with the environment set of levels A1, formed in the forbidden zone of non-interacting anti-site defects AsGa. 5) The Fermi level GaAs with clusters and thin layers of gallium atoms quickly reaches a limit value close to the value for the planar Schottky barrier metal/semiconductor boundary. Regulations the Fermi level is determined by the interface of the layers of GaAs anti-site defects. These states and simultaneously act as a slotted metal-induced state and as "renormalized" by the interaction of the state of deep levels of GaAs single defects, indicating a close relationship models based on the concept of fixing the Fermi level and the defective metal-induced states. 6) With increasing size of clusters of germanium in matrix Si the quantization level monotonically shifted deep into the forbidden band of Si, that leads to a red shift of the optical absorption edge. The most intense absorption due to transitions from a resonant state of the interface at the bottom of the conduction band of the silicon. The wave function localized hole state detects a character peculiar to single-valley approximation of the effective mass. In the model with snapped at the heterojunction cluster/potential matrix, this method gives results similar to the pseudo-calculation for clusters with dimensions greater than about 2 nm. 7) Due to the quantum-size effect in the electronic states of pyramidal quantum dots w-GaN/AlN (0001) the lower miniband derived from the state of the quantum Г-well. Overlying levels are associated with states of the lateral U-valleys and the neighborhood Г-valley of the conduction band of binary crystals. The most intensive absorption of light corresponds to waves polarized in the basal plane. The absorption of light with a polarization E || c weaker peak is shifted toward higher energies and due to the transition from the lower level to an excited level, originating from states with a line Δ. By increasing the frontal surface of the irradiated light is incident, arrays of small quantum dots GaN (~ 2 nm diameter base of the pyramid, ~ 1 nm height of the pyramid) can be used to improve the efficiency of infrared photodetectors. 8) The effect of a smooth interface potential on the electronic states in heterostructures GaAs/AlAs with representation of the transition region at heteroboundaries fragments superlattices (GaAs)n(AlAs)m(001). In this model intervalley mixing occurs at two interfaces in the region of the transition layer. Accounting for a smooth potential leads to noticeable changes in the tunneling of electrons in a thin layer structures, with particularly significant in the case, when they occur, with the participation of states in the field of short-wave mixing inter-valley. 9) The development of two-valley Г-L model of electron states in GaAs/AlAs structures (111) snapped on the border potential. Detected "front-end" state, having a maximum electron density at heterojunctions GaAs(111B)/AlAs(111A). These states decay rapidly due to the strong Г-L interaction on the border, when the layer is not limited to GaAs layers of AlAs c on both sides. 10) A correlation in the state of deep levels of intrinsic point defects with a limit position of the Fermi level in irradiated semiconductors, group III-V. A theoretical model is the most localized of the defective state of the crystal, which allows to determine the position of the Fermi level in the radiation-modified semiconductors, Schottky barrier height and breaks zones in semiconductor heterostructures. 11) Due to quantum size effects in the conduction band of superlattices (GaAs)n(AlAs)m(001) occur closely spaced competing valley with localized in the respective quantum wells wave functions. This leads to an increase in the intensity intervalley transitions compared with similar transitions in solid solutions. Averaged over the scattering channels deformation potentials in superlattices more than in the corresponding solid solutions.
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Some results of research: 1) The appearance of zero in the coefficient of transmission of electrons through heteroboundary GaAs/AlAs (001) caused by the mutual compensation of deposits from the "virtual processes" involving Г1, X1 and X3 states. This feature is not associated with any interface resonant states, as a consequence of the nature of the band spectrum manyvalley GaAs, AlAs. 2) Deep level states in the superlattice (GaAs)n(AlAs)m depend on the position in the lattice defects. Lowering of the symmetry in comparison with binary crystals leads to a partial (or complete) removal of the degeneracy of deep levels of vacancies are in secondary (outer) with respect to the Al layer, as well as to the different orientations of their charge densities. The greatest changes there are vacancies for As, located directly at the interface. 3) The results of multiband calculations electronic structure of GaN/Ga1-xAlxN (0001) satisfactorily described by the method of the envelope of the wave function, taking into account dependence of the effective mass of energy and deformation. The spontaneous and piezoelectric polarizations lead to the red or blue shift of the resonance energies depending on the thickness and location of barriers with respect to the polar axis. In superlattices (GaN)n(Ga1-xAlxN)m internal field can form a Stark ladder of electron states with a small number of ultra-thin layers, even in the absence of an external field. 4) Localized electronic states of gallium arsenide with arsenic clusters can be interpreted as the result of splitting due to interaction with the environment set of levels A1, formed in the forbidden zone of non-interacting anti-site defects AsGa. 5) The Fermi level GaAs with clusters and thin layers of gallium atoms quickly reaches a limit value close to the value for the planar Schottky barrier metal/semiconductor boundary. Regulations the Fermi level is determined by the interface of the layers of GaAs anti-site defects. These states and simultaneously act as a slotted metal-induced state and as "renormalized" by the interaction of the state of deep levels of GaAs single defects, indicating a close relationship models based on the concept of fixing the Fermi level and the defective metal-induced states. 6) With increasing size of clusters of germanium in matrix Si the quantization level monotonically shifted deep into the forbidden band of Si, that leads to a red shift of the optical absorption edge. The most intense absorption due to transitions from a resonant state of the interface at the bottom of the conduction band of the silicon. The wave function localized hole state detects a character peculiar to single-valley approximation of the effective mass. In the model with snapped at the heterojunction cluster/potential matrix, this method gives results similar to the pseudo-calculation for clusters with dimensions greater than about 2 nm. 7) Due to the quantum-size effect in the electronic states of pyramidal quantum dots w-GaN/AlN (0001) the lower miniband derived from the state of the quantum Г-well. Overlying levels are associated with states of the lateral U-valleys and the neighborhood Г-valley of the conduction band of binary crystals. The most intensive absorption of light corresponds to waves polarized in the basal plane. The absorption of light with a polarization E || c weaker peak is shifted toward higher energies and due to the transition from the lower level to an excited level, originating from states with a line Δ. By increasing the frontal surface of the irradiated light is incident, arrays of small quantum dots GaN (~ 2 nm diameter base of the pyramid, ~ 1 nm height of the pyramid) can be used to improve the efficiency of infrared photodetectors. 8) The effect of a smooth interface potential on the electronic states in heterostructures GaAs/AlAs with representation of the transition region at heteroboundaries fragments superlattices (GaAs)n(AlAs)m(001). In this model intervalley mixing occurs at two interfaces in the region of the transition layer. Accounting for a smooth potential leads to noticeable changes in the tunneling of electrons in a thin layer structures, with particularly significant in the case, when they occur, with the participation of states in the field of short-wave mixing inter-valley. 9) The development of two-valley Г-L model of electron states in GaAs/AlAs structures (111) snapped on the border potential. Detected "front-end" state, having a maximum electron density at heterojunctions GaAs(111B)/AlAs(111A). These states decay rapidly due to the strong Г-L interaction on the border, when the layer is not limited to GaAs layers of AlAs c on both sides. 10) A correlation in the state of deep levels of intrinsic point defects with a limit position of the Fermi level in irradiated semiconductors, group III-V. A theoretical model is the most localized of the defective state of the crystal, which allows to determine the position of the Fermi level in the radiation-modified semiconductors, Schottky barrier height and breaks zones in semiconductor heterostructures. 11) Due to quantum size effects in the conduction band of superlattices (GaAs)n(AlAs)m(001) occur closely spaced competing valley with localized in the respective quantum wells wave functions. This leads to an increase in the intensity intervalley transitions compared with similar transitions in solid solutions. Averaged over the scattering channels deformation potentials in superlattices more than in the corresponding solid solutions.
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