Spectroscopic anisotropy in laterally self-aligned quantum dots

The spectroscopic features observed in laterally self-aligned InGaAs/GaAs quantum dots (QDs) are compared with those in isolated QDs. Though each aligned QD keeps an individual appearance analogous to that of an isolated QD, the aligned QD shows a unique spectroscopic anisotropy attributed to coupling. The polarized photoluminescence (PL) intensity parallel to the alignment of the QDs is distinctively enhanced, which supports the anisotropic arrangement in a preferential [110] direction as shown by the atomic force microscopic image. The temperature dependence of the PL emission energy is exceptionally redshifted, in contrast with the excitation-power dependence that shows a blueshift behavior, which may possibly be explained by the carrier redistribution in anisotropically coupled QDs.