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S. T. Pavlov

Publications and source records attributed to S. T. Pavlov.

At least 19 recordsLinked to original sources
arXiv2010

The pulse and monochromatic light stimulation of semiconductor quantum wells

The light reflectance and absorbance are calculated for a quantum well (QW) the width of which is comparable with the light wave length. The difference of the refraction coefficients of the quantum well and barriers is taken into account. The stimulating pulse form is arbitrary. An existence of two closely situated discrete excitation energy levels is supposed. Such energy level pare may correspond to two magnetopolaron states in a quantizing magnetic field perpendicular to the QW plane. The relationship of the radiative and non-radiative damping is arbitrary. The final results does not use the approximation of the weak Coulomb interaction of electrons and holes.

cond-mat.mes-hall↗
arXiv2007

Resonant Transmission of a Light Pulse through a Quantum Well

Reflectance, transmittance and absorbance of a symmetric light pulse, the carrying frequency of which is close to the frequency of interband transitions in a quantum well, are calculated. Energy levels of the quantum well are assumed discrete, and two closely located excited levels are taken into account. The theory is applicable for the quantum wells of arbitrary widths when the size quantization is preserved. A distinction of refraction indices of barriers and quantum well is taken into account. In such a case, some additional reflection from the quantum well borders appears which changes essentially a shape of the reflected pulse in comparison to homogeneous medium. The reflection from the borders disappears at some definite ratios of the carrying frequency of the stimulating pulse and quantum well width.

cond-mat.mes-hall↗
arXiv2007

Effect of the Spatial Dispersion on the Shape of a Light Pulse in a Quantum Well

Reflectance, transmittance and absorbance of a symmetric light pulse, the carrying frequency of which is close to the frequency of interband transitions in a quantum well, are calculated. Energy levels of the quantum well are assumed discrete, and two closely located excited levels are taken into account. A wide quantum well (the width of which is comparable to the length of the light wave, corresponding to the pulse carrying frequency) is considered, and the dependance of the interband matrix element of the momentum operator on the light wave vector is taken into account. Refractive indices of barriers and quantum well are assumed equal each other. The problem is solved for an arbitrary ratio of radiative and nonradiative lifetimes of electronic excitations. It is shown that the spatial dispersion essentially affects the shapes of reflected and transmitted pulses. The largest changes occur when the radiative broadening is close to the difference of frequencies of interband transitions taken into account.

cond-mat.mes-hall↗
arXiv2007

The Resonant Light Absorption by Semiconductor Quantum Dots

The cross section of light absorption by semiconductor quantum dots in the case of the resonance with excitons $Γ_6 \times Γ_7$ in cubical crystals $T_d$ is calculated. It is shown that an interference of stimulating and induced electric and magnetic fields must be taken into account. The absorption section is proportional to the exciton nonradiative damping $γ$.

cond-mat.stat-mech↗
arXiv2007

The Theory of Light Scattering by Semiconductor Quantum Dots. Semiclassical Method Using Retarded Potentials

The theory of elastic light scattering by semiconductor quantum dots is suggested. The semiclassical method, applying retarded potentials to avoid the problem of bounder conditions for electric and magnetic field, is used. The exact results for the Pointing vector on large distances from a quantum dot, formulas of differential cross sections of light scattering for the monochromatic and pulse irradiation are obtained.

cond-mat.mes-hall↗
arXiv2006

Influence of Anomalous Dispersion on Optical Characteristics of Quantum Wells

Frequency dependencies of optical characteristics (reflection, transmission and absorption of light) of a quantum well are investigated in a vicinity of interband resonant transitions in a case of two closely located excited energy levels. A wide quantum well in a quantizing magnetic field directed normally to the quantum-well plane, and monochromatic stimulating light are considered. Distinctions between refraction coefficients of barriers and quantum well, and a spatial dispersion of the light wave are taken into account. It is shown that at large radiative lifetimes of excited states in comparison with nonradiative lifetimes, the frequency dependence of the light reflection coefficient in the vicinity of resonant interband transitions is defined basically by a curve, similar to the curve of the anomalous dispersion of the refraction coefficient. The contribution of this curve weakens at alignment of radiative and nonradiative times, it is practically imperceptible at opposite ratio of lifetimes . It is shown also that the frequency dependencies similar to the anomalous dispersion do not arise in transmission and absorption coefficients.

cond-mat.mes-hall↗
arXiv2006

Elastic Light Scattering by Semiconductor Quantum Dots

Elastic light scattering by low-dimensional semiconductor objects is investigated theoretically. The differential cross section of resonant light scattering on excitons in quantum dots is calculated. The polarization and angular distribution of scattered light do not depend on the quantum-dot form, sizes and potential configuration if light wave lengths exceed considerably the quantum-dot size. In this case the magnitude of the total light scattering cross section does not depend on quantum-dot sizes. The resonant total light scattering cross section is about a square of light wave length if the exciton radiative broadening exceeds the nonradiative broadening. Radiative broadenings are calculated.

cond-mat.mes-hall↗
arXiv2004

Interband electron Raman scattering in a quantum wire in a transverse magnetic field

Electron Raman scattering (ERS) is investigated in a parabolic semiconductor quantum wire in a transverse magnetic field neglecting by phonon-assisted transitions. The ERS cross-section is calculated as a function of a frequency shift and magnetic field. The process involves an interband electronic transition and an intraband transition between quantized subbands. We analyze the differential cross-section for different scattering configurations. We study selection rules for the processes. Some singularities in the Raman spectra are found and interpreted. The scattering spectrum shows density-of-states peaks and interband matrix elements maximums and a strong resonance when scattered frequency equals to the "hybrid" frequency or confinement frequency depending on the light polarization. Numerical results are presented for a GaAs/AlGaAs quantum wire.

cond-mat.mes-hall↗
arXiv2004

Influence of the magnetopolaron effect on light reflection and absorption by a wide semiconductor quantum well

Light reflection and absorption spectra by a semiconductor quantum well (QW) , which width is comparable to a light wave length of stimulating radiation, are calculated. A resonance with two close located exited levels is considered. These levels can arise due to splitting of an energy level of an electron-hole pair (EHP) due to magnetopolaron effect, if the QW is in a quantizing magnetic field directed perpendicularly to the QW plane. It is shown that unlike a case of narrow QWs light reflection and absorption depend on a QW width $d$. The theory is applicable at any ratio of radiative and non-radiative broadenings of electronic excitations.

cond-mat.mes-hall↗
arXiv2004

The magnetopolaron effect in light reflection and absorption by a wide quantum

Light reflection and absorption spectra by a semiconductor quantum well (QW), which width is comparable to a light wave length of stimulating radiation, are calculated. A resonance with two close located exited levels is considered. These levels can arise due to splitting of an energy level of an electron-hole pair (EHP) due to magnetopolaron effect, if the QW is in a quantizing magnetic field directed perpendicularly to the QW plane. It is shown that unlike a case of narrow QWs light reflection and absorption depend on a QW width $d$. The theory is applicable at any ratio of radiative and non-radiative broadenings of electronic excitations.

cond-mat.mes-hall↗
arXiv2003

Principals of the theory of light reflection and absorption by low-dimensional semiconductor objects in quantizing magnetic fields at monochromatic and pulse excitations

The bases of the theory of light reflection and absorption by low-dimensional semiconductor objects (quantum wells, wires and dots) at both monochromatic and pulse irradiations and at any form of light pulses are developed. The semiconductor object may be placed in a stationary quantizing magnetic field. As an example the case of normal light incidence on a quantum well surface is considered. The width of the quantum well may be comparable to the light wave length and number of energy levels of electronic excitations is arbitrary. For Fourier-components of electric fields the integral equation (similar to the Dyson-equation) and solutions of this equation for some individual cases are obtained.

cond-mat.mes-hall↗
arXiv2003

Analogue of the Kubo Formula for Conductivity of Spatially Inhomogeneous Systems and Electric Fields

The average of densities of currents and charges, induced by a weak electromagnetic field in spatially inhomogeneous are calculated at final temperatures. The Kubo formula for a conductivity tensor is generalized for spatially inhomogeneous systems and fields. The contributions containing electric fields and derivative from fields on coordinates are allocated. The Semiconductor quantum wells, wires and dots may be considered as spatially inhomogeneous systems.

cond-mat.mes-hall↗
arXiv2003

The Kubo-type Formula for Conductivity of Spatially Inhomogeneous Systems

The expressions for average densities of currents and charges induced by a weak electromagnetic field in spatially inhomogeneous systems are obtained. The case of finite temperatures is considered. It is shown that average values are separated into "basic" and "additional" parts. The former depends on electric fields, and the latter depends on derivatives of electric fields on coordinates. Semiconductor quantum wells, wires or dots may be considered as spatially inhomogeneous systems.

cond-mat.mes-hall↗
arXiv2002

The Quantum Theory of Conductivity of Spatially - Heterogeneous Systems

The quantum theory of conductivity of semiconductor objects, to which the quantum wells, wires and dots concern, is constructed. Average values of current and charge densities, induced by a weak electromagnetic field, are calculated. It is shown, that in both cases average current and charge densities contain two contributions, first of which is expressed through electric field, and second - through a spatial derivative of electric field. Appropriate expressions for the conductivity tensor, dependent on coordinates and applicable to any spatially-heterogeneous systems, are deduced. The results may be used in the theory of secondary light radiation from low-dimensional objects in cases of monochromatic light and light pulses.

cond-mat.mes-hall↗
arXiv2002

"One-dimensional" Coherent States and Oscillation Effects in Metals in a Magnetic Field

The "one-dimensional" coherent states are applied to describe the Shubnikov - de Haas and the de Haas-van Alphen oscillation effects in metals, semimetals, and degenerate semiconductors. The oscillatory part of the electron density of states in a magnetic field is calculated. A substantial simplification of calculations is achieved.

cond-mat.mes-hall↗
arXiv2002

Transmission of a Symmetric Light Pulse through a Wide QW

The reflection, transmission and absorption of a symmetric electromagnetic pulse, which carrying frequency is close to the frequency of an interband transition in a QW (QW), are obtained. The energy levels of a QW are assumed discrete, one exited level is taken into account. The case of a wide QW is considered when a length of the pulse wave, appropriate to the carrying frequency, is comparable to the QW's width. In figures the time dependencies of the dimensionless reflection, absorption are transmission are represented. It is shown, that the spatial dispersion and a distinction in refraction indexes influence stronger reflection.

cond-mat.mes-hall↗
arXiv2001

An echo of an exciting light pulse in quantum wells

The non-sinusoidal character oscillations appear in the transmitted, reflected and absorbed light fluxes when light pulses irradiate a semiconductor quantum well (QW), containing a large number of the equidistant energy levels of electronic excitations. A damping echo of the exciting pulse appears through the time intervals $2π\hbar/ΔE$ in the case of the very short light pulses $γ_l^{-1}\ll\hbar/ΔE$.

cond-mat.mes-hall↗