IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Tuesday Sessions
       Session SC+SS-TuA

Paper SC+SS-TuA8
Surface Passivation Effects of Deposited Ge-Nanocrystal Films Probed with Synchrotron Radiation

Tuesday, October 30, 2001, 4:20 pm, Room 122

Session: Semiconductor Nanostructures and Processing
Presenter: C.F.O. Bostedt, Lawrence Livermore National Laboratory
Authors: C.F.O. Bostedt, Lawrence Livermore National Laboratory
T. van Buuren, 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 that exhibit promising novel properties. The production of these nanostructures in the gas phase gives control over not only the size of the nanoparticles, but also over surface passivation – often not possible in other growth modes. The clusters are condensed out of supersaturated Germanium-vapor that is cooled down in a He-atmosphere and are subsequently deposited on a variety of substrates. Their surface is then subsequently passivated with different materials evaporated into the vacuum chamber. This approach allows us to probe in a controlled and dynamic fashion the effect of surface passivation on nanocluster properties. The clusters are spherical in shape and their sizes are determined by atomic force microscopy (AFM) and confirmed by transmission electron microscopy (TEM). X-ray absorption spectroscopy (XAS) was performed on thin films of Germanium (Ge) clusters. We find that the passivating agent strongly alters the electronic structure of the clusters. In general the absorption edge shifts to significantly higher energies compared to cluster films without surface passivation. This can be explained with a stronger confinement effect in the passivated films compared to unpassivated ones due to a reduction of the cluster-cluster interactions. @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.