Direct spectroscopic evidence for the formation of one-dimensional wetting wires during the growth of InGaAs/GaAs quantum dot chains

We report direct spectroscopic evidence for the formation of one-dimensional ( 1D) wetting wires ( WWs) during the Stransky-Krastanov growth of InGaAs/GaAs quantum dot ( QD) chains. The wire-like nature of these 1D WWs was demonstrated by their 1D density of states and absorption anisotropies from the photoluminescence excitation measurements. Two groups of QDs were found sitting on top of these 1D WWs and the traditional two-dimensional wetting layers, respectively, with size-dependent emission polarization anisotropies of ca. 6-25% because of their elongated shapes.