Selective area growth of InAs quantum dots formed on a patterned GaAs substrate

We describe the growth and characterization of $\mathrm{InAs}$ quantum dots (QDs) on a patterned $\mathrm{GaAs}$ substrate using metalorganic chemical vapor deposition. The QDs nucleate on the $\left(001\right)$ plane atop $\mathrm{GaAs}$ truncated pyramids formed by a thin patterned ${\mathrm{SiO}}_2$ mask. The base diameter of the resulting QDs varies from 30 to $40\mathrm{nm}$ depending on the size of the mask. With specific growth conditions, we are able to form highly crystalline surface QDs that emit at $1.6\mu \mathrm{m}$ under room-temperature photopumped conditions. The crystalline uniformity and residual strain is quantified in high-resolution transmission electron microscopy images and high-resolution x-ray reciprocal space mapping. These strained QDs may serve as a template for selective nucleation of a stacked QD active region.