Quantum well exciton-polariton light emitting diode

摘要

A light emitting device made of semiconducting materials. The device has an optical microcavity which supports a resonant mode of predetermined photon energy. Within the cavity is a quantum well of predetermined thickness and energy depth. The quantum well is designed such that it forms bound electron, exciton, lower polariton, and hole energy states of predetermined energy. The energy of an exciton state is set to equal the predetermined photon energy of the microcavity mode such that polariton states are created. A means is provided for resonantly tunneling electrons into a quantum well energy state. In a first embodiment, electrons resonantly tunnel into an electron energy state. In a second embodiment, electrons resonantly tunnel into an exciton energy state, during which tunneling the electrons simultaneously fuse with holes to form excitons. In the first embodiment, the electron state to lower polariton state transition energy is made equal to the energy of a longitudinal optical (LO) phonon of the quantum well material. This energy equivalence facilitates the rapid thermalization of resonantly tunneled electrons to combine with holes and form polaritons resonant with the cavity mode. Thermalization is rapid because it only requires the scattering of a single LO phonon. The photon component of the polariton is then emitted through the leaky cavity reflector. The second embodiment sets the exciton to polariton transition energy equal to the LO phonon energy to facilitate rapid thermalization to the polariton state. Photons are then emitted through the leaky Bragg reflector in the same manner as the first embodiment.