Non-polar a-plane ZnMgO/ZnO quantum wells grown by molecular beam epitaxy

Non-polar ( Zn, Mg) O/ZnO quantum wells ( QWs) have been grown on a r-plane sapphire by molecular beam epitaxy. The heterostructures are fully oriented and show a single wurtzite phase at least up to 40% Mg content, as evidenced by means of the x-ray pole figures analysis. The microstructure is dominated by stacking faults and related partial dislocations as shown by the transmission electron microscopy analysis. A series of QWs with different widths has then been studied, showing the absence of the quantum confined Stark effect. The photoluminescence energies of the QWs are satisfactorily simulated when taking into account the variation of the exciton binding energy with the QW width. Different approaches for the calculation of the QW exciton ground state energies are proposed and compared.