User:Tfranci/Phonon bottleneck

--Tfranci (talk) 12:49, 12 June 2010 (UTC)

In semiconductor physics, the phonon bottleneck effect is a mechanism that impedes the relaxation of excited electrons into lower energy states via phonon scattering. It is a multi-particle phenomena and is easily evidenced in semiconducting nanostructures.

Upon the creation of an excited electron - hole pair (exciton), the electron promoted to the conduction band tends to "relax" its energy, thus attempting to occupy lower energetic levels within the conduction band. This relaxation occurs most commonly via electron - phonon scattering; the excess energy is transferred to a lattice vibration (phonon) with an energy equal to that of the transition. As opposed to electrons, phonons have large momenta and small total energies thus for an electron - phonon scattering event to occur momentum and energy must be conserved, thus the electronic relaxation transition must have a small energy difference and a large momentum difference between the initial excited state and the final relaxed state.