Self-assembled SiGe quantum rings (QRs) on Si0.8Ge0.2 substrate has been formed by thermal annealing of the samples with capping Au thin films at 1100degreesC in N-2 ambient. Miniature quantum rings have a narrow distribution of diameter and height of 27.9 +/- 1.7 and 1.53 +/-0.10 nm, respectively. The formation of quantum rings was found to be mediated by the Au nanoparticles. As the size of Au nanoparticles can be adjusted, the method promises to be an effective technique to produce high density, uniform in size quantum rings. (C) 2004 Elsevier B.V. All rights reserved.