Patterned InAs quantum dot formation

We describe the growth and characterization of InAs quantum dots (QDs) on a patterned GaAs substrate using metal organic chemical vapor deposition. The InAs QDs nucleate on the [001] plane atop GaAs truncated pyramids formed in a thin patterned SiO₂ mask. The SiO₂ mask is formed using interferometric photolithography. The base diameter of the GaAs pyramids are ∼100 nm with resulting QD diameter which varies from 30 nm to 40 nm depending on the size of the mask. With specific growth conditions, we are able to form highly crystalline surface QDs. The crystalline uniformity and residual strain is quantified in high-resolution transmission electron microscopy images and high-resolution X-ray reciprocal space mapping. The QDs are capped with a GaAs layer embedding the SiO₂ within the epistructure. This process protects the growth surface from environmental contamination. The capped QDs emit at 1.6 μm under room-temperature photopumped conditions. Several masking techniques will be described including an Al_xO_y mask that can be removed in-situ.