Formation of Crystalline Germanium Nanoclusters in a Silica Xerogel Matrix from an Organogermanium Precursor

Addition of the organogermanium compound, Me 3 GeS(CH 2 ) 3 Si(OMe) 3, to a modified, conventional sol−gel formulation gives a silica xerogel doped with this molecular species. Subsequent thermal treatment of this molecularly doped xerogel under oxidizing then reducing conditions affords nanoclusters of Ge highly dispersed throughout the bulk of the xerogel matrix. Under appropriate conditions, Ge nanoclusters having an average diameter of ca. 68 Å can be formed by this procedure. Characterization of this nanocomposite material by TEM, HRTEM, EDS, XRD, micro-Raman spectroscopy, electron diffraction, and UV−visible spectroscopy indicates that the Ge nanoclusters are highly crystalline and exhibit optical properties consistent with those expected when quantum confinement effects are operative.