A GaAs polariton light-emitting diode operating near room temperature

Solid-sate physics: Practical polaritronics A tight control over light–matter interactions can be achieved at a nanometre scale in a semiconductor microcavity. The strong coupling between excitons in the semiconductor material and photons resonating in the cavity gives rise to new hybrid half-light/half-matter quasiparticles called polaritons. The unique properties of polaritons, giving rise to exotic lasing and quantum condensation effects, have the potential to spawn a new generation of particle emitters and semiconductor lasers. Polariton lasing and nonlinearities have been demonstrated in optical experiments, but it would be of considerable technological interest to demonstrate electrically driven polariton light-emitting devices. This has now been accomplished in a gallium arsenide diode that emits light directly from polariton states held at the relatively high temperature of 235 K (−38° C). The authors believe that the findings represent a significant step towards the realization of a new class of ultra-efficient polaritronic devices with unprecedented characteristics. The increasing ability to control light–matter interactions at the nanometre scale has improved the performance of semiconductor lasers in the past decade. The ultimate optimization is realized in semiconductor microcavities, in which strong coupling between quantum-well excitons and cavity photons gives rise to hybrid half-light/half-matter polariton quasiparticles 1 . The unique properties of polaritons—such as stimulated scattering 2 , 3 , parametric amplification 4 , 5 , 6 , lasing 7 , 8 , 9 , 10 , condensation 11 , 12 , 13 and superfluidity 14 , 15 —are believed to provide the basis for a new generation of polariton emitters and semiconductor lasers. Until now, polariton lasing and nonlinearities have only been demonstrated in optical experiments, which have shown the potential to reduce lasing thresholds by two orders of magnitude compared to conventional semiconductor lasers 16 . Here we report an experimental realization of an electrically pumped semiconductor polariton light-emitting device, which emits directly from polariton states at a temperature of 235 K. Polariton electroluminescence data reveal characteristic anticrossing between exciton and cavity modes, a clear signature of the strong coupling regime. These findings represent a substantial step towards the realization of ultra-efficient polaritonic devices with unprecedented characteristics.