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.