Transmission electron microscopy study of InGaAs/GaAs structural evolution near the stranski-krastanow transformation

摘要

An experimental study of the microstructure during formation and evolution of MOCVD-grwon In_(0.6)Ga_(0.4)As/GaAs quantum dots (QDs) was undertaken to provide a more thorough understanding of the underlying growth principles. Transmission Electron Microscopy (TEM) was used to examine the evolution of the In_(0.6)Ga_(0.4)As/GaAs system in order to correlate photoluminescence (PL) spectra with structural data. In particular, we have examined the QD size evolution, capped and uncapped, and its possible contribution to the slight QD PL blueshift observed before QD saturation. TEM studies in the QD coalescence regime clarify the microstructural origins of the sharp decrease in QD PL due to large, incoherent islands observed in AFM and TEM images.