The electronic properties of self-organized GaSb quantum dots (QDs) embedded in GaAs n+p diodes were investigated by capacitance–voltage and deep level transient spectroscopy. The localization energy of the hole ground state is 450 meV. State filling lowers the activation energy to 150 meV for completely charged QDs containing 15 holes. The hole retention time at room temperature for a single hole per QD is extrapolated to be in the microsecond range, about five orders of magnitude longer than in In(Ga)As/GaAs QDs. Hence, we consider GaSb/GaAs to be a suitable material system for future QD memory applications which require long storage times.

We have studied the photoluminescence from type-II GaSb/GaAs self-assembled quantum dots in magnetic fields up to 50 T. Our results show that at low laser power, electrons are more weakly bound to the dots than to the wetting layer, but that at high laser power, the situation is reversed. We attribute this effect to an enhanced Coulomb interaction between a single electron and dots that are multiply charged with holes.

Many-particle effects are investigated in the photoluminescence of type II GaSb/GaAs quantum dots (QDs). With increasing excitation density, i.e., exciton occupation, the photoluminescence shows first a blueshift and then saturates developing a plateau region. The peculiar behavior is attributed to Coulomb charging and state filling of the localized holes to dominate the many-particle regime. A high temperature stability makes the GaSb/GaAs QDs suitable for room-temperature devices.

The formation of GaSb quantum dots in a GaAs matrix in the Stranski–Krastanow growth mode under metalorganic chemical vapor deposition conditions is investigated. Transmission electron microscopical images and photoluminescence measurements show the islands to nucleate during the GaSb deposition and to grow subsequently by mass transfer from the two-dimensional wetting layer. The evolving surface morphology indicates local equilibria between quantum dots and the surrounding wetting layer regions.

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