Size anisotropy inhomogeneity effects in state-of-the-art quantum dot lasers

We describe a high angle annular dark field scanning transmission electron microscopy study of a self-assembled InAs-GaAs quantum dot (QD) laser sample providing insight into the micro-structure of the QD ensemble. A size distribution anisotropy of the QDs is observed in the two orthogonal (110) planes, and this structural information is used to develop a density of states model for the QD ensemble which is shown to be in strong agreement with a range of optical spectroscopic measurements. This link between the micro-structure and optical properties allows routes to QD device simulation. We go on to discuss how changes to the micro-structure would affect the density of states and hence laser performance.