Self-organization of the InGaAs GaAs quantum dots superlattice

The mechanism of self-organization of quantum dots (QDs) during the growth of InGaAs/GaAs multilayers on GaAs (1 0 0) was investigated with cross-sect ional transmission electron microscopy (XTEM), and double-crystal X-ray dif fraction (DCXD). We found that the QDs spacing in the first layer can affec t the vertical alignment of QDs. There seems to exist one critical lateral QD spacing, below which merging of QDs with different initial size is found to be the dominant mechanism leading to perfect vertical alignment. Once t he critical value of QDs spacing is reached, the InGaAs QDs of the first la yer are simply reproduced in the upper layers. The X-ray rocking curve clea rly shows two sets of satellite peaks, which correspond to the QDs superlat tice, and multi-quantum wells (QW) formed by the wetting layers around QDs. (C) 1999 Elsevier Science B.V. All rights reserved.