Hundreds of milliseconds long electrically controllable electroluminescence rise and decay time in GaN-ZnO heterostructures

Exciton-based logic devices are expected to be more energy efficient and compatible with the optical communication when compared with their electronic counterparts. Long and tuneable lifetime of the excitons is necessary for the development of exciton-based logic circuits. Spatially indirect excitons (SIDX), in which electron and hole parts are spatially separated, can offer not only orders of magnitude longer lifespan than the spatially direct excitons but also an electrical controllability of their recombination rate. These excitons have been observed in semiconductor-coupled quantum wells and 2D materials. However, their lifetime has never been reported to reach beyond a few hundred of microseconds. Recently, c-oriented n-ZnO/p-GaN heterointerface is shown to host a unique type of SIDX, where 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 to reside in the GaN side. Here, we report that SIDX in n-ZnO/p-GaN heterojunction can survive for several hundreds of milliseconds. Moreover, this extraordinarily long survival time can be electrically controlled. The findings thus pave the way to exploit excitons for both classical and quantum logic operations.