Emission properties and thermal annealing of InGaN/GaN multiple quantum wells with different protection layers

We investigated the effect of two-monolayer thick protection layers of GaN and AlGaN at the well growth temperature after the growth of InGaN well in InGaN/GaN MQW structures by MOCVD. The protection layers were very effective in inhibiting the re-evaporation of indium atoms regardless of the growth of GaN barriers at high temperature from TEM and PL. In addition, the use of GaN barrier grown at high temperature using GaN protection layers improved the emission efficiency due to the growth of high quality GaN without indium desorption. From the thermal treatment of as-grown samples, the red-shift of emission was observed, which was ascribed to the increased quantum confined Stark effect by thermal stress, showing negligible indium gathering and atomic intermixing.