Exciton localization in inhomogeneously broadened ZnO/MgxZn1−xO quantum wells

Abstract

Exciton localization in ZnO/MgxZn1−xOquantum wells(QWs) has been investigated systematically with various ZnO well widths for the fixed Mg0.23Zn0.77O barrier height. A strong exciton confinement is observed with an implicit dependence on the built-in electric field which is calculated to be 0.37 MV/cm. The exciton-phonon coupling strength varied significantly depending upon the degrees of exciton localization with the activation energy of 18–29 meV. The relaxation mechanism in ZnO/Mg0.23Zn0.77OQWs starts to dominate when the exciton localization energy is above the thermal energy, kBT. The band characteristics and strong exciton localization in ZnO/Mg0.23Zn0.77OQWs are attributed to the potential fluctuations associated with the inhomogeneous broadening, represented by the schematics. Show more