In-mole-fraction of InGaAs insertion layers effects on the structural and optical properties of GaSb quantum dots grown on (100) GaAs substrate

GaSb quantum dots (QDs) have been grown by solid-source molecular beam epitaxy on a 4-monolayer (ML) In_xGa_1-xAs (x = 0.07, 0.15, 0.20 and 0.25) to investigate the effects of In-mole-fraction of InGaAs insertion layers on the structural and optical properties of the GaSb QDs. The density of GaSb QDs grown is approximately 1.2-2.8×109cm^-2 on InGaAs insertion layers which depends on the In-mole-fraction. Dot shape and size change substantially. The elongation direction of the base changes from [110] to [1-10] when InGaAs insertion layers are introduced. The uniformity of GaSb QDs improves when the indium content increases. The change in their dot morphology is likely due to the modified strain at different values of indium compositions in InGaAs insertion layers. The effects of In-mole-fraction of InGaAs insertion layer on optical properties of the QDs are studied by photoluminescence (PL). PL results show the blueshift of the emission when the indium content in InGaAs insertion layer increases.