Room temperature excitonic spontaneous and stimulated emission properties in ZnO/MgZnO multiple quantum wells grown on sapphire substrate

Abstract

ZnO/Mg0.2Zn0.8O multiple quantum wells (MQWs) were grown on a c-plane sapphire (Al2O3) substrate by plasma-assisted molecular beam epitaxy. Both the spontaneous and the stimulated emission properties at room temperature (RT) in MQWs were studied under lower and higher excitation densities. The strong emission at 3.330 eV was observed in the MQWs at RT, which was attributed to the free exciton transition by the temperature-dependent photoluminescence measurement. Significantly, RT stimulated emission caused by inelastic exciton–exciton scattering was observed in the ZnO/Mg0.2Zn0.8O MQWs grown on Al2O3. Thus, the exciton binding energy was determined to be 122 meV in our MQWs.