Phenomena of nanoislands self-organization are of interest to several areas of solid-state physics. Among these objects is the "Ge on Si" heterosystem with Ge nanoislands behaving as quantum dots. The smallest germanium islands growing on the pure silicon surface are 15 nm in size. They can be lowered by growing germanium on the oxidized atomically pure surface prepared in situ in the MBE installation. A MBE installation "Katun-C" was used for synthesis on Si (100) substrates. An MBE growth chamber was used for oxidation at oxygen supply up to 10-4 Pa and the substrate temperature 400-500OC.
The process of Ge film growth was controlled using a RHEED patterns registrations. These observations indicate the absence of the stage of wetting layer formation. Therefore, germanium film growth on the oxidized silicon surface by the Volmer-Weber mechanism but not by the Stranski-Krastanow mechanism, which is characteristic of the growth of pure Si surface. Deformations of germanium lattice were studied by measuring in plane lattice constant a of the surface 2D unit cell. The film growth results in changes in the surface cell constant of Ge lattice against the constant of Si lattice. The difference may reach 7% as reported for the growth on pure Si(100) surface. The mode of parameter a variations is similar to that observed during germanium heteroepitaxy on the pure Si(100) surface. The maximal elastic deformation occurs already in the 3D island nuclei. Depending on the thickness of the deposited Ge layer, the islands are different in size and density. At the film not thicker than 5 ML, the islands on oxidized surface are less than 10 nm in base size at the density higher than 2x1012 cm-2.
The work is supported by the Russian Foundation for Basic Research (Grants 03-02-16468, 03-02-16506 and 02-02-17746) and INTAS (Grant 01-0444).
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