Spatially Indirect Excitons in GaN-ZnO Heterostructures with Long and Electrically Controllable Lifetime

Prolonged and controllable excitonic lifetimes are critical for the development of exciton-based logic devices that have superior energy efficiency and optical communication compatibility compared to their electronic counterparts. Spatially indirect excitons (SIDX) exhibit a significantly longer lifespan than direct excitons. Further, their recombination rate can be controlled through the quantum-confined Stark effect. Recently, a c-oriented n-ZnO/p-GaN heterointerface has been shown to host a unique type of SIDX, where the electron part is quantum confined in the ZnO side under the spontaneous polarization field developed at the interface. While the valence band offset makes the hole part reside in the GaN side. Here, we report that SIDX in this system can survive for several hundreds of milliseconds. Moreover, this extraordinarily long lifetime can be electrically controlled. The findings not only thus pave the way for the realization of exciton-based logic circuits for the future but also offer a platform to explore the exciting predictions made about SIDX.