EFFECTS OF ANTIMONY FLUX ON MORPHOLOGY AND PHOTOLUMINESCENCE SPECTRA OF GaSb QUANTUM DOTS FORMED ON GaAs BY DROPLET EPITAXY

Abstract

We investigated effects of the antimony flux on GaSb quantum dots (QDs) formed by droplet epitaxy. Ga droplets were first formed on GaAs and exposed to Sb4 molecular beam at 200 °C, where the flux PSb of Sb beam was varied from 2.4 to 12.8 × 10-7 Torr. The samples were then annealed for 2 minutes under the Sb flux. An atomic microscope study showed that the diameter of GaSb QDs increases and the density decreases, as the Sb flux PSb is increased. This indicates that the coalescence process of GaSb QDs occurs and is accelerated by the increase of the Sb flux. In a photoluminescence (PL) study, we observed a broad peak of GaSb QDs in all samples, while a strong luminescence of a wetting layer (WL)-like structure was found only in the samples prepared with the high Sb flux. This suggests that the PL of WL is controllable by adjusting the flux PSb of Sb beam.