Photoluminescence characterization of Zn_(1-x)Mg_xO epitaxial thin films grown on ZnO by radical source molecular beam epitaxy

摘要

The authors report that high-quality Zn_(1-x)Mg_xO alloys are very brilliant light emitters, even more brilliant than ZnO, particularly in the high-temperature region; both the emission bandwidth and the oscillator strength of the photoluminescence from Zn_(1-x)Mg_xO alloys increase remarkably with increasing Mg composition ratio x. The authors have revealed that the increase in the oscillator strength is mainly due to the increase in the activation energy required for the nonradiative recombination processes. Therefore, it is suggested that the localization of excitons, because of the compositional fluctuation, takes place in Zn_(1-x)Mg_xO alloys and that the degree of the localization increases with increasing x.