Nucleation Chronology and Electronic Properties of InAs_1–x–ySb_xP_y Graded Composition Quantum Dots Grown on an InAs(100) Substrate

We provide a detailed study of nucleation process, characterization, and electronic and optical properties of graded composition quantum dots (GCQDs) grown from the In-As-Sb-P composition liquid phase on an InAs(100) substrate in the Stranski–Krastanov growth mode. Our GCQDs exhibit diameters from 10 to 120 nm and heights from 2 to 20 nm with segregation profiles having a maximum Sb content of approximately 20% at the top and a maximum P content of approximately 15% at the bottom of the GCQDs so that hole confinement is expected in the upper parts of the GCQDs. Using an eight-band k·p model taking strain and built-in electrostatic potentials into account, we have computed the hole ground-state energies and charge densities for a wide range of InAs1–x–ySbxPy GCQDs as close as possible to the systems observed in the experiment. Finally, we have obtained an absorption spectrum for an ensemble of GCQDs by combining data from both the experiment and theory. Excellent agreement between measured and simulated absorption spectra indicates that such GCQDs can be grown following a theory-guided design for application in specific devices.