Comparison of strong coupling regimes in bulk GaAs, GaN, and ZnO semiconductor microcavities

Wide band-gap semiconductors are attractive candidates for polariton-based devices operating at room temperature. We present numerical simulations of reflectivity, transmission, and absorption spectra of bulk GaAs, GaN, and ZnO microcavities in order to compare the particularities of the strong coupling regime in each system. Indeed the intrinsic properties of the excitons in these materials result in a different hierarchy of energies among the valence-band splitting, the effective Rydberg, and the Rabi energy, defining the characteristics of the exciton-polariton states independent of the quality factor of the cavity. Knowledge of the composition of the polariton eigenstates is central to optimize such systems. We demonstrate that in ZnO bulk microcavities, only the lower polaritons are good eigenstates and all other resonances are damped, whereas upper polaritons can be properly defined in GaAs and GaN microcavities.