In(Ga)As self-assembled quantum ring formation by molecular beam epitaxy

The effect of growth conditions on the morphological properties of InAs/GaAs(001) quantum dots covered by a thin (<3 nm) GaAs cap has been studied by atomic force microscopy. Each dot turns into an elongated nanostructure at 540 degreesC upon deposition of the cap in As-4 atmosphere, while structures with two humps are obtained when capping at 500 degreesC. The use of As-2 atmosphere instead of As-4 at 500 degreesC leads to the formation of quantum rings. Photoluminescence spectroscopy and polarization photoluminescence (PL) at 15 K show dramatic changes due to the different kinds of confinement. This allows the possibility of tailoring PL emission by controlling the size and shape. (C) 2003 American Institute of Physics.