Large vacuum Rabi splitting in ZnO-based hybrid microcavities observed at room temperature

Abstract

Wide-band gap ZnO semiconductors are attractive materials for the investigation of microcavity exciton polaritons due to the large exciton binding energy and oscillator strength. We report the growth and characterization of bulk ZnO-based hybrid microcavity. The phenomenon of strong exciton-photon coupling at room temperature has been observed in the ZnO-based hybrid microcavity structure, which consists of 30 pair epitaxially grown AlN/AlGaN distributed Bragg reflector ͑DBR͒ on the bottom side of the 3 / 2 thick ZnO cavity and 9 pair SiO 2 / HfO 2 DBR as the top mirror. The cavity quality factor is about 221. The experimental results show good agreement with theoretically calculated exciton-polariton dispersion curves based on transfer matrix method. From the theoretical and experimental exciton-polariton dispersion curves with two different cavity-exciton detuning values, the large vacuum Rabi splitting is estimated to be about 58 meV in the ZnO-based hybrid microcavity.

Polariton lasing in a hybrid bulk ZnO microcavity

“…Thanks to these two facts, the regime of excitonic lasing in a planar cavity is accessible and both nonlinear excitonic emission and strong coupling have been demonstrated for various ZnO-based optical resonators. [10][11][12][13][14][15][16] In this letter, we report on polariton lasing occurring in a planar microcavity embedding a bulk ZnO layer. The cavity quality factor (Q $ 300) and the in-plane photonic disorder drive the system out-of-equilibrium and to a competition between multiple localized polariton modes at the lasing threshold.…”

Polariton condensation phase diagram in wide-band-gap planar microcavities: GaN versus ZnO

“…On the contrary, the robustness of excitons in GaN and ZnO at RT has led to an increasing interest for these materials, especially after the first observation at RT of the strong coupling regime (SCR) 23 , and of polariton lasing in bulk- 24 and quantum well-based 25 GaN MCs elaborated on sapphire substrates. Concerning ZnO MCs, the SCR at RT has been reported more recently [26][27][28][29] , followed by polariton lasing at 120K 30 , then up to 250 K 31 , and finally at RT 32,33 . The difficulty to increase the number of pairs of the distributed Bragg reflectors (DBRs) due to the lattice and thermal expansion coefficient mismatch between silicon and nitrides prevented the achievement of polariton lasing in such samples 34,35 .…”

GaN-based microcavity polariton light emitting diodes

“…Although RT polariton LED is realized in GaAs system [13], they still suffers from small exciton binding energy and oscillator strength, from this point of view, wide bandgap materials with larger exciton binding energy and oscillator strength provide more a reliable RT operation for practical polariton devices. So far the RT polariton emission and lasing are already demonstrated in several wide bandgap material systems, including GaN and ZnO [7,8,16,17,20,21] under optical pumping. The current injection wide bandgap semiconductor polariton emitters such as LED or laser are still obscene.…”