Vertical alignment of laterally ordered InAs and InGaAs quantum dot arrays on patterned (001) GaAs substrates

We demonstrate vertical alignment of laterally ordered self-assembled quantum dot (QD) arrays stacked on artificially pre-patterned substrates with two-dimensional hole arrays. The initial InGaAs layer is directly grown on the periodically modulated surface in order to exactly control nucleation sites of QDs to be stacked. After growing three InGaAs dot layers with GaAs spacers as a buffer, laterally ordered InAs dots are grown as an optically active layer. The cross-sectional images of transmission electron microscopy reveal vertical alignment of the stacked QDs. Photoluminescence signal at room temperature is detected from the three-dimensional QD superlattice. (C) 2002 Elsevier Science B.V. All rights reserved.