Electric-field-dependent carrier capture and escape in self-assembled InAs/GaAs quantum dots

Photoluminescence and complementary photocurrent spectroscopy, both as a function of electric field, are used to probe carrier capture and escape mechanisms in InAs/GaAs quantum dots. Carrier capture from the GaAs matrix is found to be highly field sensitive, being fully quenched in fields of only 15 kV/cm. For fields less than 20 kV/cm, carriers excited in the wetting layer are shown to be captured by the dots very effectively, whereas for fields in excess of 50 kV/cm tunnel escape from the wetting layer into the GaAs continuum is dominant. For excitation directly into the dots, radiative recombination dominates up to 100 kV/cm.