Ge nanocrystals (Ge NCs) embedded in a multilayered superlattice structure have been fabricated and investigated. The presence of Ge NCs was confirmed by Raman scattering and X-ray diffraction measurements. The average size of Ge NCs was modulated by the sputtering time of Ge-rich layer and possible mechanisms have been proposed. The blue shift of optical absorption edge was observed with the decrease of nanocrystal size. The photoluminescence showed broad bands centred at similar to 1.77 eV and similar to 2.01 eV for 3.9 nm and 3.0 nm nanocrystals, respectively, which are consistent with the theoretical calculation in literature. The properties of shifted optical absorption and red luminescence are tentatively explained by quantum confinement in the Ge NCs. (C) 2010 Elsevier B.V. All rights reserved.