Germanium (Ge) nanodots of about 7 nm size and 2 x 10(12) cm(-2) density were formed on slightly oxidized silicon surfaces. The spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM) revealed clearly the size, aspect ratio and interface structures among the nanodots, oxide layers and silicon substrates. In particular, a Ge-rich thin layer underneath SiO2 layers was found for the first time in these kinds of samples. The elemental distribution through the interface was analyzed by EELS and EDX in the Cs-corrected STEM. The high-resolution Cs-corrected annular dark field (ADF)-STEM image shows clearly the existence of a Ge-rich crystalline layer and its geometry against the oxide layer from the Z-contrast image. A new growth model of the Ge nanodots on slightly oxidized silicon surfaces was proposed. (c) 2008 Elsevier B.V. All rights reserved.