Observation of exciton polaritons in a ZnO microcavity with HfO2/SiO2 distributed bragg reflectors

We have investigated the characteristics of the exciton polaritons in a ZnO microcavity. The microcavity consists of an effective one-wavelength thick ZnO active layer and HfO2/SiO2 distributed Bragg reflectors (DBRs) at the bottom and top. We adopted rf magnetron sputtering and pulsed laser deposition for the preparation of the DBR and ZnO layer, respectively. Angle-resolved reflectance and photoluminescence spectra demonstrate the formation of the cavity polaritons. The cavity polariton dispersions are analyzed using a phenomenological Hamiltonian for the coupling between the cavity photon and three kinds of fundamental excitons labeled A, B, and C. The vacuum Rabi splitting energy is estimated to be similar to 80 meV. The giant Rabi splitting energy reflects the large exciton oscillator strength of ZnO.