Experimentally observed two-exponential decay of excitonic transitions in GaAs-Al Gal — As multiple quantum wells has been successfully interpreted in terms of the exciton transfer between the continuum (free carriers) and the bound states. The calculation results obtained from this exciton-transfer model are in excellent agreement with experimental observations. The rates of the exciton transf...

We have found experimentally, that the exciton luminescence rise times in GaAdAlGaAs quantum wells oscillate as a function of incident laser energies. Guided by MonkCarlo simulations we interpret these results as the occurrence of selective LO-phonon assisted exciton formation. In the photoexcitation of semiconductors excitons can be generated either directly with high momentum or by free elect...

Effective tight-binding models have been introduced to describe vertical electronic excitations in branched conjugated molecules. The excited-state electronic structure is characterized by quantum particles (excitons) that reside on an irregular lattice (graph) that reflects the molecular structure. The methodology allows for the exciton spectra and energy-dependent exciton scattering matrices ...

The nature of the primary photoexcitations in semiconducting single-walled carbon nanotubes (S-SWCNTs) is of strong current interest. We have studied the emission spectra of S-SWCNTs and two different π-conjugated polymers in solutions and films, and have also performed ultrafast pump-probe spectroscopy on these systems. The emission spectra relative to the absorption bands are very similar in ...

In group-III nitrides in use for white light-emitting diodes (LEDs), optical gain, measure of luminous efficiency, is very low owing to the built-in electrostatic fields, low exciton binding energy, and high-density misfit dislocations due to lattice-mismatched substrates. Cuprous halides I-VII semiconductors, on the other hand, have negligible built-in field, large exciton binding energies and...

We calculate exciton energy of single wall carbon nanotubes (SWNTs). The exciton energy depends on the surrounding materials of the SWNT [1]. This environmental effect is expressed by the dielectric constant [2]. In previous paper we used the static dielectric constant in order to reproduce the resonance Raman experiment for bundle samples [3,4]. However, since the dielectric constant depends o...

Radius of quantum dot Exciton binding energy and electron-hole recombination probability are presented as the two important metrics for investigating effect of dot size on electronhole interaction in CdSe quantum dots. Direct computation of electron-hole recombination probability is challenging because it requires an accurate mathematical description of electron-hole wavefunction in the neighbo...

We develop a theory to calculate exciton binding energies of both two-and three-dimensional spin polarized exciton gases within a mean field approach. Our method allows the analysis of recent experiments showing the importance of the polarization and intensity of the excitation light on the exciton lumines-cence of GaAs quantum wells. We study the breaking of the spin degeneracy observed at hig...