Abstract
This paper reviews the optical properties of ZnO/(Zn, Mg)O single quantum wells grown by molecularbeam epitaxy. Both heteroepitaxial quantum well growth along the polar c-direction and homoepitaxial quantum wellgrowth on the nonpolar M plane cases are considered. The optical properties of these quantum wells are investigatedby using re ectance, continuous wave photoluminescence, and time-resolved photoluminescence spectroscopies. Thequantum-con ned Stark e ect dominates the properties of the excitons for polar quantum wells. The magnitude of theinternal electric eld that is induced by both spontaneous and piezoelectric polarizations is determined by comparingthe experimental results with a variational calculation of excitonic energies and lifetimes. For nonpolar quantum wells,the optical spectra reveal strong in-plane optical anisotropies, as predicted by the group theory. Moreover, the radiativerecombination of free excitons is dominating the quantum well photoluminescence even at room temperature.