Enhanced internal quantum efficiency in non-polar ZnO/Zn0.81Mg0.19O multiple quantum wells by Pt surface plasmons coupling.

Non-polar-oriented ZnO/Zn0.81Mg0.19O multiple quantum wells (MQWs) were grown on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The internal quantum efficiency (η(int)) of the non-polar MQWs was only 1.8%. The degraded quality of non-polar MQWs is the main factor for the low η(int). Besides improving the quality of non-polar MQWs, an effective way to enhance the UV emission of the non-polar MQWs by sputtering Pt nanoparticles has been used. Employing the resonant coupling between UV emission from the MQWs and Pt nanoparticle surface plasmons (SPs), a 20-fold enhancement of the UV emission has been achieved under the optimized sputtering time. Moreover, the η(int) value of the non-polar MQWs has been strongly improved with the help of Pt. 6.7-fold enhancement of η(int) has been achieved due to SPs coupling. It paves a new way in designing highly efficient non-polar LEDs.