The growth of germanium by ultra high vacuum-chemical vapour deposition (UHV-CVD) on a thin SiO(2) layer (0.6 nm) formed on Si(001) was investigated by real-time reflection high energy electron diffraction (RHEED), scanning electron microscopy (SEM), and transmission electron microscopy ITEM). It was observed that the growth of Ge at 600 degrees C on a 2 monolayers thick SiO(2) (0.6 nm) film remains perfectly coherent with the Si (001) substrate. The mechanism of reduction of SiO(2) is also discussed for higher Ge deposition temperatures. it was found to involve both Si from the substrate and Ge from the gas phase. (C) 2008 Elsevier B.V. All rights reserved.