Physics of optoelectronic devices

The poor radiative efficiency in quantum-box luminescence is tentatively explained as an intrinsic effect rather than the usually invoked effect of etch damages. From the recently calculated decreased relaxation rate in zero-dimensional (OD) systems under 100-200-nm lateral quantization, we propose that electrons captured from the barriers in the upper levels of quantum boxes are retained in their cascade to the fundamental states for more than nanoseconds. Due to the mutual orthogonality of quantum states in a box, no luminescence, or much less than in 2D or 3D, can be obtained from these stored electrons with reasonable assumptions for the hole population. Magnetic-confinement experiments in quantum-well lasers support our conclusion. A realistic model at low temperature describes more quantitatively the observed strong decay of the radiative efficiency in quantum boxes and pseudowires with decreased lateral dimensions.

Intrinsic mechanism for the poor luminescence properties of quantum-box systems

In this study, we investigate the parabolic potential effects on the ground and excited energy states of two-electron quantum dot with impurity inside an infinite spherical confining potential well. The wave function and energy eigenvalues were calculated using a modified variational optimization procedure based mainly on quantum genetic algorithm and Hartree–Fock–Roothaan method. The results show that the parabolic potential and impurity charge have a strong effect on the energy states and ionization energies. It is worth pointing out that as impurity charge increases, the ionization energy rises, but the ionization dot radius decreases. On the other hand, as parabolic potential increases, the ionization energy decreases, but the ionization dot radius increases.

Electronic structure of two-electron quantum dot with parabolic potential

We theoretically study the optical absorption in a quantum well with the semi-parabolic potential plus the semi-inverse squared potential (SPSIS) in the presence of a static magnetic field in which both one- and two-photon absorption processes have been taken into account. The expression of the magneto-optical absorption coefficient (MOAC) is expressed by the second-order golden rule approximation including the electron–LO phonon interaction. We also use the profile method to obtain the full width at half maximum (FWHM) of the absorption peaks. Our numerical results show that either MOAC or FWHM strongly depends on the confinement frequency, temperature, and magnetic field but their dependence on the parameter β is very weak. The temperature dependence of FWHM is consistent with the previous theoretical and experimental works.

Magneto-optical properties of semi-parabolic plus semi-inverse squared quantum wells

Combined effects of magnetic and electric fields on the confined exciton in an InAs1−xPx/InP (x=0.2) quantum well wire are investigated taking into account the geometrical confinement effect. Variational formulism, within the frame work of effective mass approximation, is applied to obtain the exciton binding energy. The second order harmonic generation and the optical gain are carried out using compact density method. The strain effects are included with the confinement potential in the Hamiltonian. The energy difference of the ground and the first excited state is found in the presence of magnetic and electric fields taking into the consideration of spatial confinement effect. The result shows that the optical properties are more influenced taking into account the effects of geometrical confinement, magnetic field and electric field. It is shown that the telecommunication wavelength can be achieved with the suitable doping barrier material with the wire material and the external perturbations.

Combined effects of magnetic and electric fields on the interband optical transitions in InAs/InP quantum wire

Phonon effects on interband optical transitions in InAs0.8P0.2/InP quantum wire

Absorption coefficients for interband optical transitions in a strained InAs1-xPx/InP quantum wire

Binding Energy of a Magneto-exciton in an InAsP Quantum Well Wire for the Potential Application of Telecommunication Networks☆

Hydrostatic pressure-induced exciton binding energy in an InAs0.8P0.2/InP quantum well wire is investigated taking into account the geometrical confinement effect. Numerical calculations are carried out using variational approach within the single-band effective-mass approximation. The compressive strain contribution to the confinement potential is included throughout the calculations. The energy difference of the ground and the first excited state is found with the consideration of spatial confinement effect in the influence of pressure. The second-order susceptibility of harmonic generation is carried out using the compact density method. The optical gain as a function of incident photon energy is computed in the presence of the hydrostatic pressure. The result shows that the range of wavelength for the potential applications of telecommunications (1.3–1.55 μm) can be obtained by the application of the hydrostatic pressure. We believe that the obtained results can be applied for tuning the ranges of fib...

S. Saravanan

Papers

Combined effects of magnetic and electric fields on the interband optical transitions in InAs/InP quantum wire

Phonon effects on interband optical transitions in InAs0.8P0.2/InP quantum wire

Absorption coefficients for interband optical transitions in a strained InAs1-xPx/InP quantum wire

Binding Energy of a Magneto-exciton in an InAsP Quantum Well Wire for the Potential Application of Telecommunication Networks☆

Pressure-induced interband optical transitions in an InAs0.8P0.2/InP quantum wire