Direct Interband Light Absorption Research Articles

Screw dislocation and external fields effects on the Kratzer pseudodot

In this research, we investigate the influence of the screw dislocation on the energy levels of nonrelativistic electrons on a two-dimensional solid taking into account the deformed Kratzer potential under an external magnetic and the Aharonov–Bohm (AB) fields. We obtain the bound state energy eigenvalues equation and the corresponding wave functions by using the Frobenius method. We also calculate the direct interband light absorption coefficient and threshold frequency of absorption in a quantum pseudodot. Some of the numerical results are given.

Exciton states and direct interband light absorption in the ensemble of toroidal quantum dots

One electron and exciton states in toroidal quantum dot (QD) have been considered. The convenient coordinate system has been defined and the Schrodinger equation has been solved in these coordinates. The electron energy spectrum and wave function dependence on the geometrical parameters of toroidal QD have been obtained. The comparison with the results obtained by numerical methods has been done. Optical absorption has been considered in both cases of “small” toroid when the interaction of an electron and a hole is neglected and cases of relatively “large” toroid when the correlation between the particles has been taken into account. Interband optical transitions have been considered in the ensemble of toroidal QDs. The selection rules for quantum transitions and absorption edge dependence on the geometrical parameters have been obtained.

Electronic States and Optical Transitions in an Asymmetric Quantum Dot Molecule

In the framework of adiabatic approximation the electronic states and direct interband absorption of light in the asymmetric double quantum dot molecule (QDM) having a shape of Cassini lemniscate revolution are discussed. Analytical expressions for the wave functions and energy spectrum of the electron in the QDM are derived. Nonmonotonic split and step-like behavior of the energy spectrum is revealed due to the possibility of the electron tunneling between quantum dots (QDs) in the molecule. The corresponding selection rules of quantum transitions for the direct interband absorption of light are obtained. The absorption edge characteristics depending on the QDM geometrical sizes are also revealed.

Optical properties of narrow band prolate ellipsoidal quantum layers ensemble

Electronic states and direct interband light absorption in the ensemble of prolate spheroidal quantum layers are considered. The problem of finding the one-electron wave function and energy spectrum have been solved exactly. Absorption edge dependence on the thickness of the layer in the strong size quantization regime has been obtained. The effect of nonparabolicity of the dispersion law of energy levels and optical absorption have been taken into account and calculations are carried out for the cases of both parabolic and Kane’s dispersion laws. Selection rules have been revealed. Absorption coefficient dependence on the frequency of incident light has been obtained, taking into account dispersion of nanolayer thicknesses for the cases of both symmetric and asymmetric distribution functions.

Electronic and optical properties of a double quantum dot molecule with Kane’s dispersion law

In the framework of the adiabatic approximation the electronic states and direct interband absorption of light in the double quantum dot molecule (QDM) are discussed. Cases of both standard parabolic and Kane's dispersion law are considered. Analytical expressions for the wave functions and energy spectrum of the electron in the QDM are treated. The split of energy levels due to the possibility of the electron tunneling between quantum dots (QDs) in the molecule is revealed. The corresponding selection rules of quantum transitions for the direct interband absorption of light are obtained. The absorption edge behavior characteristics depending on the QDs geometrical sizes and the width of the QDs connecting region are revealed as well.

Theory of electronic states and direct light absorption in the biconical (superellipsoidal) quantum dot

The electronic states in the GaAs biconical (superellipsoidal) quantum dot (QD) in a strong and weak size quantization (SQ) regimes are theoretically investigated within the framework of the geometrical adiabatic approximation. An atypical linear term in the effective confining potential forms a family of non-equidistant sublevels in the electron energy spectrum, whereas the quadratic term leads to the appearance of the equidistant energy levels as a consequence of the symmetry of the QD. In the weak size quantization regime the motion of the exciton's center-of-gravity is quantized, which leads to the appearance of the additional Coulomb sub-levels in the energy spectrum of the QD. The direct interband absorption of light in the biconical QD is also considered in both strong and weak SQ regimes. The dependences of the absorption edge on QD geometrical parameters are revealed in the linear and quadratic approximations of the effective potential adiabatic terms. Corresponding selection rules for quantum transitions are obtained as well.

Prolate spheroidal quantum dot: Electronic states, direct interband light absorption and electron dipole moment

Excitonic states and direct interband light absorption are considered in prolate spheroidal quantum dot. The problem of finding the one electron wave function and energy spectrum have been solved exactly. Three regimes of size quantization have been considered. Absorption edge dependence on the small semiaxes of the spheroid has been obtained. The probability of the direct interband transitions has been calculated and the selection rules for quantum numbers have been obtained. It has been shown that in prolate spheroidal quantum dot the exact value of the electron ground state with high accuracy coincides with the value of ground state in strongly prolate ellipsoidal quantum dot obtained in the framework of the adiabatic approximation. The dependence of z component of the electron dipole moment has been studied on the small semiaxes of the prolate spheroidal quantum dot.

Oblate spheroidal quantum dot: electronic states, direct interband light absorption and pressure dependence

Exitonic states and direct interband light absorption are considered in an oblate spheroidal quantum dot. The problem of finding the one electron wave function and energy spectrum has been exactly solved. Three regimes of size quantization have been considered. Absorption edge dependence on the small semiaxes of the spheroid and its hydrostatic pressure dependencies have been obtained. It has been shown that the exact value of the electron ground state in the oblate spheroidal quantum dot coincides with high accuracy to the value of ground state in strongly oblate ellipsoidal quantum dot obtained in the framework of the adiabatic approximation. The dependences of the electron ground state energy on the hydrostatic pressure and temperature have been studied.

Direct interband light absorption in the cylindrical quantum dot with modified Pöschl–Teller potential

In this paper the direct interband light absorption in cylindrical quantum dot with modified Pöschl–Teller potential made of GaAs is studied. For the regime of strong size quantization analytical expressions for the particle energy spectrum, absorption coefficient and dependencies of effective threshold frequencies of absorption on the geometrical sizes of quantum dot are obtained. The selection rules corresponding to different transitions between quantum levels are found. To facilitate the comparison of obtained results with the probable experimental data, size dispersion distribution of growing quantum dots by the geometrical sizes using two experimentally realizing distribution functions has been taken into account. Distribution functions of Lifshits–Slezov and Gaussian have been considered.

Direct interband absorption of light in a strongly oblate truncated ellipsoidal quantum dot's ensemble

Within the framework of adiabatic approximation the energy levels and direct interband absorption of light in a strongly oblate truncated ellipsoidal quantum dot's ensemble are studied. Analytical expressions for the particle energy spectrum and absorption threshold frequencies in the regime of strong size quantization are obtained. Selection rules for quantum transitions are revealed. To facilitate the comparison of obtained results with the probable experimental data, size dispersion distribution of growing quantum dots by the minor semiaxe by two experimentally realizing distribution functions have been taken into account. Distribution functions of Lifshits-Slezov and Gaussian have been considered.

DIRECT INTERBAND LIGHT ABSORPTION IN A SPHERICAL QUANTUM DOT WITH THE MODIFIED PÖSCHEL-TELLER POTENTIAL

The energy levels and direct interband absorption of light in a spherical quantum dot with a modified Pöschel-Teller confining potential are studied. Analytical expressions for the particle energy spectrum and absorption threshold frequencies in the regime of strong size quantization are obtained. Selection rules for quantum transitions are revealed. Red shift and blue shift of absorption threshold has been observed depending on the values of half-width and depth of confining potential, correspondingly.

Electronic states and light absorption in quantum dot molecule

The electronic states and direct interband absorption of light in quantum dot molecule (QDM) consisting 4 or 5 QDs are investigated. The electron energy levels and wave functions are calculated. It is shown that the energy levels are split in azimuth direction. In the case of the presence of the central QD in QDM an additional splitting in the radial direction is revealed. The suggested method can be used to calculate the electronic states and light absorption of arbitrary number QDM. The results are useful for the application of the QDM to photoelectric devices.

Direct Interband Light Absorption in Strongly Prolated Ellipsoidal Quantum Dots' Ensemble.

Within the framework of adiabatic approximation, the energy levels and direct interband light absorption in a strongly prolated ellipsoidal quantum dot are studied. Analytical expressions for the particle energy spectrum and absorption threshold frequencies in three regimes of quantization are obtained. Selection rules for quantum transitions are revealed. Absorption edge and absorption coefficient for three regimes of size quantization (SQ) are also considered. To facilitate the comparison of obtained results with the probable experimental data, size dispersion distribution of growing quantum dots by the small semiaxe in the regimes of strong and weak SQ by two experimentally realizing distribution functions have been taken into account. Distribution functions of Lifshits–Slezov and Gaussian have been considered.

Direct interband light absorption in a strongly prolated ellipsoidal quantum dot

Within the framework of adiabatic approximation the energy levels and direct interband light absorption in a strongly prolated ellipsoidal quantum dot are studied. Analytical expressions for the particle energy spectrum and for absorption threshold frequencies at three regimes of size quantization are obtained. Selection rules for quantum transitions are revealed.

Electron states and light absorption in a thin ellipsoidal quantum lens in the presence of a strong magnetic field

Within the framework of adiabatic approximation the energy levels and direct interband light absorption in a thin ellipsoidal quantum lens in the presence of a magnetic field are studied. Analytical expressions for the particle energy spectrum and for the absorption threshold frequencies in the regime of strong size quantization for the cases of ellipsoidal and spherical cross-section segments are obtained. Selection rules for quantum transitions are revealed.

Direct interband light absorption in a strongly oblated ellipsoidal quantum dot

Within the framework of adiabatic approximation the energy levels and direct interband light absorption in a strongly oblated ellipsoidal quantum dot are studied. Analytical expressions for the particle energy spectrum and for the absorption threshold frequencies at three regimes of quantization are obtained. Selection rules for quantum transitions are revealed.

Direct interband light absorption in a cylindrical quantum dot in quantizing magnetic field

In this paper the direct interband transitions in cylindrical quantum dot (QD) made of GaAs are studied in the presence of a magnetic field. Two models of QD confinement potential are discussed. For both models the expressions for absorption coefficients and dependencies of effective threshold frequencies of absorption on the value of applied magnetic field and on geometrical sizes of QD are obtained. The selection rules corresponding to different transitions between quantum levels are found.