Large-scale US nanobelts were synthesized using a simple physical evaporation of US particles under controlled conditions on an Si substrate without any catalyst. The synthesized nanobelts are single crystals with a hexagonal structure growing along the [0 0 1] direction and the growth process follows a vapor-solid mechanism. Two emission bands around 517 and 735 nm of the nanobelts are observed, and the X-ray photoelectron spectroscopy (XPS) results reveal that the band at 735 nm originates from the V-s(+) vacancies. (C) 2004 Elsevier B.V. All rights reserved.