We have obtained thanks to reduced pressure-chemical vapor deposition germanium nanocrystals in a high quality SiO2 matrix. A perfect control of (i) the tunnel and control oxide layer thicknesses and (ii) the germanium nanocrystals density and diameter has been achieved. Scanning electron microscopy was used to (i) determine the nucleation and growth rate of the germanium nanocrystals and (ii) evaluate their morphological stability during their embedding. We have also studied the influence of thin selectively grown Si films in order to passivate the surface of the germanium nanocrystals. X-ray photoelectron spectroscopy has shown that the germanium nanocrystals' surface properties are better with a Si capping. The polycrystalline state of the nanocrystals has been evaluated with X-ray diffraction. Transmission electron microscopy image reveals the lack of germanium diffusion and precipitation in the SiO2 matrix. (C) 2010 Elsevier B.V. All rights reserved.