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This paper presents a theoretical investigation of nonlinear properties of coupled quantum dots in the peanut configuration. A complete Hamiltonian is formulated using the adiabatic method and the confinement energy is represented in a cylindrical coordinate system. The effective energy for the slow subsystem is analysed and graphed as a function of a fixed value of axial coordinate for both the asymmetric and symmetric peanut QD cases. The electron motion in the presence of an electric field in the vertical direction is considered, and the eigenfunctions and energy spectrum of electron motion are determined for the same direction utilising the finite element method. The dependence of the first three energy levels on the electric field is shown, and the electron probability density for the ground state and the first excited state is plotted. In addition, calculations for the nonlinear optical properties are presented, particularly optical rectification, second harmonic generation and third harmonic generation. The results demonstrate that these properties can be effectively controlled by varying the external electric field. The findings suggest that coupled peanut QDs hold significant potential for applications in high-performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

In the framework of the adiabatic approximation, the energy states of electron as well as the direct light absorption are investigated in conical quantum dot. Analytical expressions for particle energy spectrum are obtained. The dependence of the absorption edge on geometrical parameters of conical quantum dot is obtained. Selection rules are revealed for transitions between levels with different quantum numbers. In particular, it is shown that for the radial quantum number transitions are allowed between the levels with the same quantum numbers, and any transitions between different levels are allowed for the principal quantum number. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The absorption of light in an ensemble of non-interacting cylindrical quantum dots in the presence of a magnetic field is discussed using a model consisting of dots with rectangular infinitely-high potential barriers. The ensemble’s absorption coefficient is calculated — as well as the threshold frequency of absorption — as a function of the applied magnetic field and the quantum dot size. Theoretical results are compared with experimental data on magneto-luminescence in an In0.53Ga0.47As/InP cylindrical quantum dot system. In addition, using a perturbation theory framework, the influence of excitonic effects on the behaviour of the electron-hole energetic spectrum of said system is discussed. [ABSTRACT FROM AUTHOR]

Interband transitions in a narrow-gap InSb cylindrical quantum dot (QD) have been theoretically studied in the regime of strong dimensional quantization with allowance for a nonparabolic dispersion of electrons and light holes. The corresponding absorption coefficients and threshold frequencies for a QD array are calculated within the framework of a two-band Kane model for electrons and light holes and a parabolic dispersion law for heavy holes. These threshold frequencies fall in the IR range. Quantitative calculations are performed using the recent data of Moiseev et al. [1] on the growth of InSb quantum dots by liquid phase epitaxy. [ABSTRACT FROM AUTHOR]

Direct optical absorption of light is theoretically investigated in a spherical quantum dot from GaAs. The confinement potential of the dot is approximated as parabolic. Three regimes of size quantization are discussed: weak, strong, and intermediate. The corresponding threshold frequencies of absorption are determined. A comparison with the case of a spherical quantum dot with rectangular infinitely high confinement potential is performed.© 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

The impurity states in quantum dot with parabolic confinement were studied in adiabatic approximation. The analytical expressions for the energy of ground and excited states were obtained. It was shown, that the influence of walls results in raising the ground energy level. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]