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

TL;DR

This study compares the strong coupling regimes in bulk GaAs, GaN, and ZnO microcavities through numerical simulations, revealing material-specific differences in polariton state characteristics relevant for room-temperature devices.

Contribution

It provides a detailed comparison of the exciton-polariton regimes in different wide bandgap semiconductors, highlighting how intrinsic properties influence polariton eigenstates.

Findings

ZnO microcavities support only lower polaritons as good eigenstates.

GaAs and GaN microcavities can define upper polaritons.

Material properties determine the hierarchy of exciton-polariton energies.

Abstract

Wide bandgap 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 between the valence-band splitting, the effective Rydberg and the Rabi energy, defining the characteristics of the exciton-polariton states independently of the quality factor of the cavity. The 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.