Photoluminescence of self-assembled InSb quantum dots grown on GaSb as a function of excitation power, temperature, and magnetic field

Abstract

We report measurements of photoluminescence (PL) from self-assembled InSb quantum dots (QD's) grown by metal-organic vapor-phase epitaxy in a matrix of GaSb as a function of excitation power, temperature, and magnetic field. PL is observed in the region 1.7--1.8 \ensuremath{\mu}m from InSb quantum dots. For low excitation power the PL is dominated by the lowest quantum dot transition energy. When the excitation power is increased the quantum dot transition increases in energy by \ensuremath{\sim}11 meV, and further transitions are observed from the wetting layer, bulk acceptor, and free excitons. Magneto-PL is used to calculate the in-plane dot confinement energies by fitting the data to the ground state of a Fock-Darwin set of energy levels. The in-plane confinement energy deduced increases from \ensuremath{\sim}6 to \ensuremath{\sim}18 meV as the excitation power is increased. This is similar to the increase in the quantum dot transition energy, and suggests that this is due to a progressive population of a distribution of strongly communicating dots with decreasing lateral sizes. Further support for this picture comes from the temperature dependence of the quantum dot transition energy, which is also found to increase by a relatively similar amount as the temperature is raised from 11 to 50 K, following a correction for the temperature dependence of the bulk energy band gaps.