[en] The problem of how the probability of trapping of charge carriers into quantum dots via the wetting layer influences the steady-state and time-dependent luminescence of the wetting layer and quantum dots excited via the matrix is analyzed in the context of some simple models. It is shown that the increase in the integrated steady-state luminescence intensity of quantum dots with increasing area fraction occupied by the quantum dots in the structure is indicative of the suppression of trapping of charge carriers from the wetting layer into the quantum dots. The same conclusion follows from the independent decays of the time-dependent luminescence signals from the wetting layer and quantum dots. The processes of trapping of charge carriers into the InAs quantum dots in the AlAs matrix at 5 K are studied experimentally by exploring the steady-state and time-dependent photoluminescence. A series of structures with different densities of quantum dots has been grown by molecular-beam epitaxy on a semi-insulating GaAs (001) substrate. It is found that the integrated photoluminescence intensity of quantum dots almost linearly increases with increasing area occupied with the quantum dots in the structure. It is also found that, after pulsed excitation, the photoluminescence intensity of the wetting layer decays more slowly than the photoluminescence intensity of the quantum dots. According to the analysis, these experimental observations suggest that trapping of excitons from the wetting layer into the InAs/AlAs quantum dots at 5 K is suppressed.

[en] Transport properties of a 2D electron gas located at a short distance from the surface (15-32.5 nm) in an AlGaAs/GaAs heterojunction were studied. A pronounced effect of the surface on the behavior of the conductivity of the 2D electron gas, as well as metallic gate screening of the scattering of two dimensional electrons by charged centers, were observed

[en] We present a study of the optical phonon spectrum of relaxed In_xAl_1-xAs epitaxial layers grown by molecular-beam epitaxy on GaAs substrates in the whole range of In content (x = 0 divide 1) using macro- and micro-Raman and IR spectroscopies.

[en] In this study we fabricated lateral superlattices (LSLs) based on the selectively doped GaAs/AlAs heterostructures with a high-mobility two-dimensional (2D) electron gas. The LSLs were formed using the electron-beam lithography and lift-off techniques, which produced a set of metallic strips on top of a heterojunction. The amplitude of the 2D electron gas modulation in the LSL was controlled by the gate voltage applied to the metallic strips. The LSLs with two different periods (a = 200 nm and 500 nm) were used to investigate the influence of microwave radiation with the frequency of 110–150 GHz on the 2D electron transport at the temperature T = 1.6 K in the magnetic field B < 1 T. We have found that zero-resistance states (ZRSs) appear under the microwave radiation in the 2D systems with a unidirectional periodic modulation. These ZRSs are located at the minima of commensurability oscillations

[en] The results of numerical simulation and study of lasing characteristics of semiconductor verticalcavity surface-emitting lasers based on Al_xGa_1-xAs alloys are presented. Lasers exhibit stable single-mode lasing at a wavelength of 795 nm at low operating currents ∼1.5 mA and an output power of 350 μW, which offers prospects of their applications in next-generation chip-scale atomic clocks

[en] A semiconductor Bragg microcavity structure for single photon emitters is designed and implemented. The design provides the efficient current pumping of selectively positioned InAs quantum dots within a micrometer-size aperture, high external quantum yield, and low divergence of the emitted radiation