Excitonic transitions in ZnO/MgZnO quantum well heterostructures

In this work we present the calculation of the excitonic transition energies in ZnO/MgZnO quantum well heterostructures, accounting for the effects of the exciton-phonon interaction. The results of our calculations clearly show that the description of the electron-hole interaction by means of the static screened Coulomb potential and the use of the polaron masses for the electron and the hole leads to a poor agreement with available experimental data. On the other hand, including the exciton-phonon interaction in the calculation of the exciton binding energies, leads to the values of the excitonic transitions which agree very well with the recently published experimental data. A critical discussion of the choice of the physical parameters used in ZnO is also presented, which leads us to suggest a value for the heavy-hole band mass of 0.78m(0) and a conduction-valence band ratio in the range 60/40-70/30. (C) 2001 American Institute of Physics.