Imbedding germanium quantum dots in silica by a modified Stober method

Monodispersed silica nanoparticles 20 nm in diameter were synthesized with germanium quantum dots (QDs) as seeds using a modified Stober process. The resulting structures comprise of germanium QD core within a silica sphere (Ge@SiO2). Films of the Ge@SiO2 Stober particles result in an average QD...QD distance of 9.6 nm, which is less than the maximum distance required for good electron transfer (10 nm). Thus, this method represents an efficient alternative to the previously reported liquid phase deposition (LPD) of silica on Ge QDs where many silica particles contained more than one QD, resulting in a wide range of QD...QD distances. (C) 2013 Elsevier Ltd. All rights reserved.