Controlling the uniformity of self-assembled InAs/GaAs quantum dots by a combined GaAs/InGaAs strained buffer layer

We report optical and structural properties of self-assembled InAs quantum dots (QDs) grown on a combined GaAs/In_0.12Ga_0.88As strained buffer layer on GaAs substrates by low-pressure metalorganic chemical vapor deposition. The thickness of GaAs in the combined GaAs/In_0.12Ga_0.88As strained buffer layer is varied (from 0 to 5 nm) to examine its effect on the optical and structural properties of the self-assembled InAs QDs. We demonstrate that the uniformity of the QDs can be significantly improved with increasing the thickness of GaAs, and highly uniform InAs QDs with a narrow inhomogeneous linewidth of about 20 meV can be achieved when the thickness of GaAs is increased to 2 nm.