Binding energies of excitons in polar quantum well heterostructures

Abstract

We present a calculation of the variation of the binding energy of a heavy-hole exciton in a highly ionic quantum well structure, as a function of well width using a variational approach. We include the effects of exciton-phonon interaction and of mismatches between the particle masses and the dielectric constants of the well and barrier layers. The effect of exciton-phonon interaction is described in terms of an effective potential between the electron and the hole, derived by Pollmann and Büttner ͓J. Pollmann and H. Büttner, Phys. Rev. B 16, 4480 ͑1977͔͒ using an exciton-bulk optical-phonon Hamiltonian. We find that the values of the exciton binding energies we calculate agree very well with those obtained using a more rigorous but a complicated approach due to Zheng and Matsuura ͓R. Zheng and M. Matsuura, Phys. Rev. B 58, 10 769 ͑1998͔͒ in which they consider an exciton interacting with the confined-longitudinal optical phonons, interface phonons, and half-space phonons. Our method has the advantage of being considerably simpler, more efficient to use and is much easier to generalize to include the effects of external perturbations such as electric and magnetic fields. We compare the results of our calculations with the available experimental data in a few ionic quantum well structures and find a very good agreement. We show that for an appropriate understanding of the experimental data in ionic quantum well structures one must properly account for the exciton-phonon interaction.

Optical properties of ZnO-based quantum structures

“…This tendency of the L w dependence of the exciton transition energy was qualitatively reproduced by calculation. As reported by Coli, Senger and Bajaj [29,30], incorporation of the effects of exciton-phonon interaction and quantum confinement in the calculation of the EBE, leads to the values of the excitonic transitions that agree better with our experimental data.…”

Optical properties of ZnO/(Zn, Mg)O quantum wells

“…These values are consistent with a ZnO exciton binding energy of 60 meV. The conduction-band offset ratio is taken at 0.8 [32].…”

Monte Carlo simulation of localization dynamics of excitons in ZnO and CdZnO quantum well structures

“…It is likely that the effective lifetime ͑re-lated to 0 ͒ is longer. 7 Here we try to evaluate precise Cd concentration at irradiated region of the sample from a variational calculation 17 where the electron-phonon interaction is taken into account. If the concentration is set to 4.3%, the transition energy is calculated to be 3.288 eV, which is very close to the exciton transition energy at 5 K.…”