Great photoluminescence enhancement in Al-sputtered Zn0.78Mg0.22O films.

ABSTRACT

Zn0.78Mg0.22O thin films were grown on a-plane sapphire substrates by plasma-assisted molecular beam epitaxy. Compared with ZnO, the crystal quality of Zn0.78Mg0.22O thin films degrades significantly, which results in low internal quantum efficiency (ηint). Besides improving the quality of Zn0.78Mg0.22O, an effective method has been used to enhance the internal quantum efficiency and the UV emission of Zn0.78Mg0.22O by sputtering Al nanoparticles. Taking advantage of the resonant coupling between UV emission of Zn0.78Mg0.22O film and Al nanoparticle surface plasmons (SPs), a 59-fold enhancement of the UV emission and a 3.5-fold enhancement of ηint has been achieved under the optimized sputtering time. Moreover, the enhancement ratio is stable after two months. It paves a facile way in fabricating high-efficiency UV optoelectronic devices.