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-TuA4
X-Ray Absorption and Emission Studies of Diamond Nanoclusters

Tuesday, October 30, 2001, 3:00 pm, Room 122

Session: Semiconductor Nanostructures and Processing
Presenter: T. van Buuren, Lawrence Livermore National Laboratory
Authors: T. van Buuren, Lawrence Livermore National Laboratory
J. Plitzko, Lawrence Livermore National Laboratory
C.F.O. Bostedt, Lawrence Livermore National Laboratory
N. Franco, Lawrence Livermore National Laboratory
L.J. Terminello, Lawrence Livermore National Laboratory
Correspondent: Click to Email
The conduction and valence band structure of bulk diamond and diamond nanoclusters have been measured using x-ray absorption and x-ray emission spectroscopies. The diamond nanoclusters are commercially available products from the Straus chemical corporation and are synthesized in a detonation wave from high explosives. X-ray diffraction and TEM show that the nanodiamond powder is crystalline and approximately 3.5 +/- 1.0 nm in diameter. The nanodiamond K-edge absorption and emission show the same spectral features as bulk diamond with low impurity levels. The C1s core exciton feature clearly observed in the K-edge absorption edge of bulk diamond is not observed in the nanodiamond spectra. A possible explanation for this is a broadening due to a distribution of particle size. The depth of the second gap in the nanodiamond spectra is shallower than that of bulk diamond. This effect has been observed previously and attributed to quantum confinement. We note that no blue shift measured in the position of nanodiamond conduction edge when compared to the bulk diamond contrary to a recent publication that has reported large conduction band shifts in CVD grown diamond nanoclusters.@footnote 1@ Experiments are in progress to measure the nanodiamond conduction band edge from the EELS spectra acquired with a field emission TEM. We compare our conduction band data to the published measurements and comment on the differences. Soft x-ray emission measurements of the valence band structure of the diamond nanocluster will also be presented. The electronic structure of the nanodiamond will be compared to recent results on Si and Ge nanoclusters and the effects of reduced sizes on the electronic structure of group IV semiconductors will be discussed.@footnote 2@ The work is supported by the US-DOE, BES Ma-terial Sciences under contract W-7405-ENG-48, LLNL. @FootnoteText@ @footnote 1@ Y.K. Chang et.al. PRL 82, 5377 (1999). @footnote 2@ van Buuren et.al. PRL 80, 3803 (1998).