Formation and optical characteristics of strain-relieved and densely stacked GaSb∕GaAs quantum dots

The authors report the formation and optical characteristics of type-II, strain-relieved, and densely stacked GaSb∕GaAs quantum dots (QDs) using an interfacial misfit (IMF) growth mode. A moderate V/III ratio during the growth of GaSb QDs produces strain-relieved QDs facilitated by the IMF array without Sb segregation associated with defects and threading dislocations. In contrast, a low V/III ratio establishes conventional Stranski-Krastanov QDs. The strain-free nature of the IMF QDs allows densely packed, multistacked ensembles which retain very high crystalline quality demonstrated by x-ray diffraction, room-temperature photoluminescence, and electroluminescence. The possibility for dense stacking enabled by the strain-relieved growth mode may prove beneficial for QD sensors, emitters, and solar cells.