Scanning tunneling microscopy (STM) and photoelectron spectroscopy. (PES) have been used to investigate the nucleation, growth, and structure of beryllium on Si(1 1 1)-(7 x 7). STM indicates that a chemical reaction occurs at temperatures as low as 120 K, resulting in a nano-clustered morphology, presumed to. be composed of A beryllium silicide compound. Upon annealing to higher temperatures, PES data indicate that beryllium diffuses into the selvage region. High temperature annealing (- 117 5 K) results in the formation of a universal ring cluster structure suggesting a Be-Si bond length less than 2.5 Angstrom, in agreement with previous calculations regarding hypothetical Be2Si. (C) 2002 Elsevier Science B.V. All rights reserved.