Surface Conductivity of Diamond: A Novel Doping Mechanism |
| Journal |
Advances in Science and Technology (Volume 48) |
| Volume |
Diamond and Other New Carbon Materials IV |
| Edited by |
P. VINCENZINI and E. CAPPELLI |
| Pages |
93-102 |
| DOI |
10.4028/www.scientific.net/AST.48.93 |
| Online since |
October, 2006 |
| Authors |
Jürgen Ristein,
Paul Strobel,
Lothar Ley
|
| Keywords |
Diamond, Doping, Fullerene, Surface Electronic Property |
| Abstract |
One of the most amazing features of diamond is the p-type surface conductivity which
occurs when intrinsic material is hydrogen terminated and brought into contact with appropriately
chosen adsorbates. Experiments during the last decade have revealed the different roles of the
surface acceptors and of the covalent carbon-hydrogen surface bonds: providing unoccupied
electronic states, and lowering the energy barrier for electron transfer from the diamond,
respectively. The simplest and historically first method to supply surface acceptors, i.e. exposing
hydrogenated diamond to air, provides, unfortunately, the most complex electronic system acting as
surface acceptors, namely solvated ions within atmospheric wetting layers. In that case electron
transfer is accompanied by a red-ox reaction that finally induces the hole accumulation.
A much simpler case of transfer doping has been demonstrated for C60F48 as molecular surface
accpeptors. In this case, the doping yield as a function of surface coverage can be modelled
quantitatively by the transfer doping mechanism. Also, pure C60 can be adopted for transfer doping,
but the formation of the van-der-Waals solid is required in this case to circumvent the electron
correlation energy for charge transfer to a single fullere cage. The C60 layers can be stabilized by
oxygen-mediated polymerisation without loosing their doping efficiency. |
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