Polaron lifetime and energy relaxation in semiconductor quantum dots

Abstract

We show that the anharmonicity driven instability of optical phonons leads in semiconductor quantum dots to a decay of polaron states which otherwise would be everlasting. By such a mechanism a single electron in an excited dot state can relax down to the ground state even if the electron energy difference markedly differs from the optical phonon energy.

Influence of quasibound states on the carrier capture in quantum dots

“…We find that two polaron states are formed, labeled ͉1͘ and ͉2͘ as in Ref. 12. The Rabi splitting between ͉1͘ and ͉2͘ is given by E Rabi ϭ5.2 meV, giving a measure of the Fröhlich coupling strength.…”

Carrier relaxation mechanisms in self-assembled(In,Ga)As∕GaAsquantum dots: EfficientNarvaez1, Bester2, Zunger3 2006Phys. Rev. B

“…On the other hand, when a sole electron is present and no hole, the inter-shell relaxation time slows down by a factor of about 2-10. For instance, in n-doped (In,Ga)As/GaAs quantum dots the low-temperature P → S relaxation time has been extracted from pump-probe infra-red spectroscopy and is in the range of 20-65 ps in the experiments of Zibik et al Several relaxation mechanisms have been proposed as responsible for the fast inter-shell relaxation: multi-phonon emission, 32 Auger (carrier-carrier) scattering, 33,34,35,36 and polaron relaxation 37,38,39,40 .…”

One- and two-phonon capture processes in quantum dots

“…It has been shown 8,18 that carriers in discrete QD states can couple strongly to LO phonons, forming polarons. The formation of polarons can strongly affect carrier relaxation in QDs.…”