AVS 49th International Symposium
    Nanometer Structures Wednesday Sessions
       Session NS-WeM

Paper NS-WeM1
Electronic Structure of Nitrogen Doped Ultrananocrystalline Diamond

Wednesday, November 6, 2002, 8:20 am, Room C-207

Session: Nanostructured Materials
Presenter: J. Birrell, University of Illinois at Urbana-Champaign
Authors: J. Birrell, University of Illinois at Urbana-Champaign
O. Auciello, Argonne National Laboratory
J.A. Carlisle, Argonne National Laboratory
J.E. Gerbi, Argonne National Laboratory
J.M. Gibson, Argonne National Laboratory
D.M. Gruen, Argonne National Laboratory
Correspondent: Click to Email
The local bonding structure of ultrananocrystalline diamond (UNCD) thin films synthesized using Ar/CH@sub 4@/N@sub 2@ microwave plasmas has been investigated using near-edge x-ray absorption fine structure (NEXAFS). These films exhibit a dramatic increase is electrical conductivity (up to 150 @ohm@@super -1@ cm@super -1@) as nitrogen gas is added to the plasma. Theoretical models predict that this is due to an increase in band gap states due to the presence of nitrogen at the grain boundaries. C 1s NEXAFS experiments have been performed to ascertain the ratio of sp@super 2@/sp@super 3@ bonded carbon in these films. It was found that, as nitrogen is added, the amount of sp@super 2@-bonded carbon increases by roughly %50 compared to the undoped films, but overall the films remain largely sp@super 3@-bonded. The sp@super 3@ @sigma@@super *@ exciton, located at ~289 eV, diminishes in intensity, however, in spite of an observed increase in grain size with nitrogen content in the plasma. These results, as well as previous experiments using high resolution transmission electron microscopy, are used to explain the observed changes in the materials properties of nitrogen doped UNCD.