Structure of InAs quantum dots-in-a-well nanostructures

InAs/InGaAs quantum dots-in-a-well nanostructures based on GaAs are a promising candidate for optoelectronic devices with the important emission wavelength of View the MathML source. We present cross-sectional scanning tunneling microscopy data, showing material reorganization depending on the process of GaAs cap layer growth on top of the quantum dot (QD) nanostructures. QDs capped with 2 nm GaAs prior to an extended growth interruption have a truncated pyramidal shape, typical base lengths of 20–25 nm, and 5–7 nm height. Those capped by a thicker GaAs layer show identical shapes, but their sizes are generally larger with about 30 nm base length and 6–9 nm height. Furthermore, some of these large QDs contain nanovoids, which form during the capping process and can be avoided in the case of a thin GaAs cap layer.