Correlated photoluminescence blinking phenomenon on InGaN/GaN nanopillar structures

Abstract

Light-emitting devices that take advantage of the wide bandgap characteristics of InGaN/GaN are widely used in the industry. However, inhomogeneities have been reported in their photoluminescence (PL) mapping at the nanometer and submicrometer scale, even in samples of high crystal quality. In addition, a blinking phenomenon (time variation of PL intensity) under photoexcitation has been reported in relation to these inhomogeneities. The reason why this blinking phenomenon occurs is still unclear; it has been observed in quantum dots and other single and multilayer quantum well structures. Nevertheless, there are very few publications on nanopillar InGaN quantum well samples, which are the focus of this research. Here, we report and analyze the behavior of the blinking phenomena on a nanopillar sample. We noticed that the blinking of the pillars is somehow synchronized on a long timescale among several spatially separated nanopillars. We demonstrated that the synchronization is not due to random intensity fluctuations. We suggest instead that the synchronization is caused by a nonlinear response of the quantum wells to the UV source. In other words, when the stimulation intensity surpasses a certain value, it triggers an ON/OFF state switch in the PL of some of the pillars. Even if preliminary, our study helps to provide clues to understanding the mechanism of the occurrence of the blink phenomenon.