Plasmonic enhancement of current-driven whispering gallery polariton device of single microwire based heterojunction via Rh nanocubes deposition

Abstract

Strong exciton-polariton coupling formed in semiconductor micro/nanostructures can open up the possibilities for developing low-dimensional, ultralow-threshold sources of coherent light. In this work, a n-ZnO microwire/p-GaN heterostructure was constituted to achieve current-driven whispering gallery polariton light-emitting diode (LED). The single ZnO microwire with hexagon-shaped cross section, can induce a strong coupling between ZnO exciton and whispering gallery mode photon, leading to the formation of exciton-polaritons. By depositing rhodium nanocubes (RhNCs) on the ZnO microwire, light-emitting intensity of the polariton LED is significantly enhanced. More importantly, the coupling strength of exciton-polariton feature via the resulting Rabi splitting energy, is significantly increased up to 515 meV, which is much higher than that of the bare ZnO MW based LED (~ 400 meV). RhNCs with desired ultraviolet plasmons can facilitate strong coupling of exciton-polaritons in the as-fabricated LED, which further being proved through angle-resolved electroluminescence measurements. We expect that these results provide new avenues to achieve highly strong exciton-photon coupling strengths, and greatly promote the progress of fabricating ultralow threshold coherent light sources and nonlinear optoelectronic devices in the short-wavelengths.