We report on the formation of nanocrystalline selenium (NC-Se) on Si substrate by ultra-high vacuum physical deposition combined with rapid thermal annealing (RTA). NC-Se in a trigonal phase with an average diameter around 20 nm was formed during RTA on the amorphous selenium film at 180 degrees C. The NC-Se exhibits a broad and strong photoluminescence at similar to 1.7 eV at room temperature. Systematic optical investigations were carried out, and the emission was ascribed to the recombination between donor- and acceptor-like states at the NC-Se/a-Se interface. (C) 2011 Elsevier B.V. All rights reserved.