Realization of linearly polarized exciton emission in wurtzite zinc oxide quantum dots

Abstract

Linearly polarized exciton emission from a quantum dot is very appealing for polarized light emitting diodes and quantum information science and technologies. However, it has been very difficult to access it, because conventional wurtzite quantum dots (QDs) usually favor circularly polarized exciton emission originating from a single electron bound to a hole with dominant heavy hole ($A$ band) character. Here we explore the exciton fine structure of wurtzite ZnO QDs by means of plane-wave million-atom atomistic pseudopotential calculations and a configuration interaction approach. We demonstrate that linearly polarized emission could be realized in these QDs by (i) enhancing the quantum confinement effects and (ii) applying hydrostatic pressure. Such an exciton has a polarization exclusively along the $c$-axis direction of the QDs, which derives from a single electron bounded to a hole state with a split-off hole ($C$-band) character. This work paves the way for the exploration of the fundamental properties of wurtzite ZnO QDs and their potential applications in optoelectronic devices and quantum technologies.