Intraband magnetospectroscopy of singly and doubly charged n-type self-assembled quantum dots

The influence of quantum dot occupancy and incident light polarization on the carrier-lattice interactions in electron-doped InAs quantum dots grown on GaAs has been investigated up to 28 T by far-infrared magnetotransmission spectroscopy. An enhancement of the electron-phonon coupling with increased electron population from one to two electrons per dot is observed, in close agreement with the predicted √2 increase due to the antisymmetrization of the electron wave function in the two-electron quantum dot system. This contrasts with two-dimensional systems in which the polaron coupling strength is reduced with increasing electron density due to the screening effect of multiple carriers on the electron-phonon interaction. A clear change of the polarization dependence for transitions from the ground to the first excited state from linear to circular has been observed as the Zeeman splitting becomes larger than the zero-field excited state splitting energy.