Fabrication of GaSb quantum rings on GaAs(0Â 0Â 1) by droplet epitaxy

We report the achievement in the fabrication of self-assembled GaSb quantum rings (QRs) on GaAs(0 0 1) substrates by droplet epitaxy technique using molecular beam epitaxy. Surface morphology was characterized by atomic force microscopy. The QR formation can be described by the diffusion of Ga atoms out of an initial Ga droplet during crystallization with Sb flux. The understanding of the formation mechanism lights up the way to grow more complex GaSb nanostructures by droplet epitaxy. The optical properties of GaSb QRs in a GaAs matrix were investigated by photoluminescence (PL). Power- and temperature-dependent PL measurements were performed to study the carrier dynamics and to observe the characteristics of type-II band alignment.