AVS 49th International Symposium
    Nanometer Structures Tuesday Sessions
       Session NS+EL-TuA

Paper NS+EL-TuA7
Production and Structure of Gas-phase Prepared Germanium Nanocrystals

Tuesday, November 5, 2002, 4:00 pm, Room C-207

Session: Quantum Dots
Presenter: C. Bostedt, Lawrence Livermore National Laboratory
Authors: C. Bostedt, Lawrence Livermore National Laboratory
T. van Buuren, Lawrence Livermore National Laboratory
T.M. Willey, Lawrence Livermore National Laboratory
J. Plitzko, Lawrence Livermore National Laboratory
T. Moller, Hasylab at DESY, Germany
L.J. Terminello, Lawrence Livermore National Laboratory
Correspondent: Click to Email
Clusters and nanocrystals represent a new class of materials, which exhibits promising novel properties. Germanium nanoparticles are particularly interesting, as the cubic as well as the tetragonal crystal phases have been reported for particle sizes below 5 nm, depending on the production method. We have developed a gas-aggregation based production method for germanium nanoclusters, with which nanocrystals in the bulk-like cubic phase from 1 to 10 nm in size can be produced. The clusters are condensed out of supersaturated Germanium-vapor, which is cooled down in a He-atmosphere and are subsequently deposited on a variety of substrates. The particle sizes and phases have been well characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD) and atomic force microscopy (AFM). The crystal phase - production method relationship is discussed. Only little is know about the surface structure of nanocrystals. Information about the surface structure is difficult to obtain. No distinct particle boundaries can be imaged with TEM. Photoemission spectroscopy (PES) has been shown to be a powerful tool to investigate bulk-crystal semiconductor surfaces. PES experiments have been performed on Ge nanocrystal films and a disordered surface shell around a crystalline core is deduced for the nanoparticles. . @FootnoteText@ C. Bostedt acknowledges a fellowship from the German Academic Exchange Service DAAD in the HSP-III program, N. Franco from the Spanish Education and Culture Office. The work is supported by the US-DOE, BES Material Sciences under contract W-7405-ENG-48, LLNL.