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 0.78m0 and a conduction-valence band ratio in the range 60/40–70/30.