A two-stage molecular beam epitaxial growth method to fabricate small and uniform Ge quantum dots on Si(100)

In this paper, a two-stage growth method is reported for fabricating small and high-density Ge quantum dots on a Si(1 0 0) substrate. In the first sta ge coherent Ge islands with relatively large dimension but high density wer e grown based on the Stranski-Krastanov mode. A Si spacer layer was then de posited on the top of the Ge dots. In the second stage, smaller Ge dots wer e grown in the areas where the larger Ge islands exist under the Si spacer. Tile effective lateral scale of these dots is found to be less than 30 nm, and their vertical scale is less than 2 nm, as measured by atomic force mi croscopy and cross-sectional transmission electron microscopy. (C) 2001 Els evier Science B.V. All rights reserved.