Polarization dependent photocurrent spectroscopy of InAs/GaAs quantum dots

We have performed interband photocurrent spectroscopy on self-assembled InAs/GaAs quantum dots using a graded index separate confinement heterostructure in waveguide geometry. The photocurrent spectrum of the quantum dots is found to be shifted to higher energies in comparison to the photoluminescence spectrum. The polarization dependent measurements show that the valence band ground states of strained InAs islands have heavy hole character. In a structure with seven vertically stacked quantum dot layers separated by 10 nm GaAs spacers, we find a change in the photocurrent spectra which is evidence for vertical coupling. (C) 1999 American Institute of Physics. [S0003-6951(99)01541-7].