Exciton states and interband optical transitions in ZnO/MgZnO quantum dots

Within the framework of the effective-mass approximation, the exciton states confined in wurtzite ZnO/MgZnO quantum dot (QD) are calculated using a variational procedure, including three-dimensional confinement of carriers in the QD and the strong built-in electric field effect due to the piezoelectricity and spontaneous polarizations. The exciton binding energy and the electron–hole recombination rate as functions of the height (or radius) of the QD are studied. Numerical results show that the strong built-in electric field leads to a remarkable electron–hole spatial separation, and this effect has a significant influence on the exciton states and optical properties of wurtzite ZnO/MgZnO QD.