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Abstract

We have overgrown GaAs (0 0 1) substrates, patterned with dense square
arrays of round-shaped nanometer-sized holes, with GaAs and In(Ga)As.
For GaAs overgrowth, the initial holes transform into larger
well-defined multicornered holes. A subsequent deposition of InGaAs or
InAs onto this template causes the formation of an ordered array of
laterally closely spaced In(Ga)As quantum dots (QDs)-termed QD
molecules. For GaAs buffer layers thicker than 18 monolayer, the QD
molecules tend to align in [1 1 0] direction. On the other hand, if we
overgrow the patterned hole array directly with InGaAs, we observe the
formation of [(1) over bar 1 0]-aligned QD molecules. Overgrowth of
such QD molecule arrays. with a Ga(Al)As spacer and, a second InGaAs QD
layer results in the formation of about 1 million perfectly
site-controlled InGaAs QDs. Furthermore, we investigate the
photoluminescence property of a vertically and laterally aligned InAs
QD array and simulate the strain energy density distribution generated
by the buried QDs. (C) 2003 Elsevier B.V. All rights reserved.