High Internal Quantum Efficiency ZnO/ZnMgO Multiple Quantum Wells Prepared on GaN/sapphire Templates for Ultraviolet Light Emitting Diodes

5-Period ZnO/Zn0.9Mg0.1O Multiple Quantum Wells (MQWs) were fabricated by plasma-assisted molecular beam epitaxy. The dominant edge threading dislocations in epitaxial films were dramatically reduced by using GaN/Al2O3 as substrates. As a result, a record high internal quantum efficiency of 61% at 300 K was obtained for the ZnO/Zn0.9Mg0.1O MQWs.