Structural and optical characteristics of laterally self-aligned InGaAs quantum dots

The structural and the optical characteristics of laterally self-aligned InGaAs/GaAs quantum dots (QDs) have been analyzed through mutual comparisons among four samples with different parameters. An anisotropic arrangement develops with increasing number of stacks, and high-temperature capping allows isolated QDs to be spontaneously organized into a one-dimensionally-aligned chain-like shape over a few pm. Moreover, the migration time allowed by growth interruption plays an additional important role in the chain arrangement of QDs. The QDs capped at high temperature exhibit blue shifts in the emission energy, which may be attributed to a slight outdiffusion of In from the InGaAs QDs. An estimate from the energy shift reveals that the compositional variation of In is 0.05.