Spectroscopy of an ensemble of In0.5Ga0.5As quantum dots following highly localized hole injection by a scanning tunneling microscope

Luminescence spectroscopy following highly localized carrier injection into an ensemble of indium gallium arsenide quantum dots (QD's), where high spatial resolution is achieved by employing a scanning tunneling microscope, is presented. From the low-temperature tunneling current and the gap voltage dependences of the hole injection conditions, the relationship between carrier density, energy, and capture has been examined. In contrast to the inhomogeneously broadened photoluminescence, low tunneling current induced luminescence exhibits sharp excitonic lines of typical widths of 1.5–2.0 meV. With increasing tunneling current and gap voltage, the carrier dynamics of carrier diffusion into a real QD population manifest themselves through state-filling effects, increased carrier diffusion, and the population of the neighboring QD's.