Light Absorption Involving Longitudinal Optical Phonons in Semiconductor Quantum Dots

A theory of single-photon interband transitions involving optical phonons in semiconductor quantum dots (QDs) has been developed. This theory assumes that the electron subsystem of QDs with infinite potential walls is in strong confinement, and its energy spectrum can be described according to the two-band semiconductor model. Longitudinal optical phonons are considered to be related to the QD electron subsystem via polar (Frohlich) electron-phonon interaction. It is shown that, in these approximations, only the off-diagonal part of electron-phonon interaction leads to the generation of electron-hole pairs with the participation of phonons; the selection rules for these transitions differ from those for zero-phonon transitions. Analytical expressions for the light-absorption coefficients of ensembles of identical and size-distributed QDs have been obtained.