Cavity Polaritons in InGaN Microcavities at Room Temperature

Abstract

Cavity polaritons are observed in InGaN quantum well (QW) microcavities at room temperature. High-quality microcavities are fabricated by the wafer-bonding of InGaN QW layers and dielectric distributed Bragg reflectors. The anticrossing behavior of strong exciton-photon coupling is confirmed by vacuum-field Rabi splitting obtained from reflection measurements. This strong coupling is also enhanced by increasing the integrated oscillator strength coupled to the cavity mode. The oscillator strength of InGaN QW excitons is 1 order of magnitude larger than that of GaAs QW excitons.

( In , Ga ) N ∕ Ga N microcavities with double dielectric mirrors fabricated by selective removal of an (Al,In)N sacrificial layer

“…In this case the excitonic mode is too broad and at too low an energy to see polariton coupling effects. 5,6,9 The measured Q factors lie within the range of the best reported values ͑400-750͒ for similar MCs with double dielectric Bragg mirrors [7][8][9] but here the use of GaN substrates with low threading dislocation densities gives the added benefit of improved epitaxial quality. As will be apparent from the examples discussed, measurements at different points on the two MCs produced significantly different PL spectra.…”

“…5,6 The so-called fully hybrid approach exploits the well-established properties of high-reflectivity dielectric DBRs for both upper and lower mirrors, and offers the potential for higher finesse MCs. [7][8][9][10] Fabricating a MC of this type requires accessing the underside of the active region by removal of the substrate and buffer layers. Laser lift-off ͑LLO͒ from a sapphire substrate, 7,8 plasma etching of a SiC substrate, 9 and wet chemical etching of a silicon substrate 10 have all been employed to achieve this.…”

“…[7][8][9][10] Fabricating a MC of this type requires accessing the underside of the active region by removal of the substrate and buffer layers. Laser lift-off ͑LLO͒ from a sapphire substrate, 7,8 plasma etching of a SiC substrate, 9 and wet chemical etching of a silicon substrate 10 have all been employed to achieve this. After substrate removal, further thinning of buffer layers is usually required to accurately define the desired cavity length, and it is essential to have a reliable method to achieve this objective.…”

Finite-size fluctuations and photon statistics near the polariton condensation transition in a single-mode microcavity

“…Although in some parameter regimes current experiments are far from thermal equilibrium, there are several reasons to study the equilibrium behavior. The above-threshold luminescence in some recent experiments 6 is suggestive of thermal equilibrium, and as microcavities continue to develop 24,25 experiments can be expected to reach states closer to thermal equilibrium. Furthermore, the behavior close to equilibrium is expected to be similar to that in equilibrium, and an understanding of the equilibrium physics provides the basis for developing nonequilibrium theories.…”

BCS-BEC crossover in a system of microcavity polaritons

“…Although current experiments may remain far from equilibrium, there are several reasons to study the equilibrium behaviour. As the quality of microcavity fabrication, and particular the quality of mirrors improve 23,24 , experiments can be expected to reach states closer to thermal equilibrium. Further, the nature of experimental signatures for coherence close to equilibrium are expected to be similar to those in thermal equilibrium.…”