Exciton In Spherical Quantum Dot Research Articles

Hydrostatic pressure and electric field effects and nonlinear optical rectification of confined excitons in spherical quantum dots

The effects of hydrostatic pressure and applied electric field on an interacting electron–hole pair in a semiparabolic quantum dot are studied under the density-matrix formalism and the effective-mass approximation. The binding energies of the first confined exciton states are calculated as a function of the confinement strength. The nonlinear optical rectification is also studied as a function of the hydrostatic pressure, the applied electric field, and the confinement strength. The results show that the resonant peak of the nonlinear optical rectification can be red or blue shifted by external probes such as hydrostatic pressure, applied electric field, and the confinement strength.

Binding energy of heavy excitons in spherical quantum dots under hydrostatic pressure

AbstractThe binding energy of heavy hole excitons in a spherical GaAs–Ga1–x Alx As quantum dot under isotropic hydrostatic pressure was calculated using the Hylleraas coordinate system and a variational approach within the approximation of the effective mass. The influences of hydrostatic pressure on the effective masses of the electron and the heavy hole, the dielectric constant and the conduction‐ and valence‐band offsets between the well and the barriers are taken into account in the calculation. The binding energy is computed as a function of hydrostatic pressure, the dot sizes and the Al(x) concentration. The results show that the binding energy derived from exciton increases with the pressure, especially for small quantum dots. Also, we have found that the binding energy increases with the pressure and the concentration for a fixed quantum dot radius, which can be useful for technological applications. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Low Magnetic Field Effect on the Polarisability of Excitons in Spherical Quantum Dots

We present a theoretical study of the simultaneous effects of magnetic and electric fields on the ground state energy of an exciton confined in CdS and CdSSe spherical quantum dots. The effect of the quantum confinement is described by an infinitely deep potential well in the framework of the effective mass approximation. The effects of the external perturbations are treated within the Hassé variational method. The variations of the diamagnetic coefficient D are determined as a function of the dot radius R. The influence of the quantum confinement and the magnetic field strength on the excitonic polarisability α is analysed.