University of Birmingham > Talks@bham > Condensed Matter Physics Seminars > Surface conducting diamond: surface transfer doping with fluorinated fullerene

Surface conducting diamond: surface transfer doping with fluorinated fullerene

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  • UserDr Chris Pakes, La Trobe University, Victoria, Australia
  • ClockFriday 18 November 2011, 14:00-15:00
  • HousePhysics East 217.

If you have a question about this talk, please contact Elizabeth Blackburn.

Upon exposure to air or appropriate surface-trapped molecules, hydrogen-terminated diamond exhibits a p-type surface conductivity [1]. Electron transfer from the diamond valence band into the lowest unoccupied molecular orbital (LUMO) of surface adsorbates such as fullerene (C60) and fluorinated fullerene (C60F48) gives rise to sub-surface hole accumulation and an upward band bending. Changes in the electronic properties of the diamond surface that accompany charge transfer have been extensively reported. However, little attention has been paid to the evaluation of the electronic properties of the molecular adsorbates on the hydrogen-terminated surface.

The electronic properties of the transfer-doped C(100):H surface and of the molecular acceptors will be examined via a series of X-ray photoelectron spectroscopy experiments, performed using laboratory and synchrotron-based light sources. We shall discuss the origin of a surface dipole that is induced at the diamond-fullerene interface and show that for the case of C60F48 acceptors, the molecules exist in two distinct charge states when deposited on the diamond surface. This will allow us to explore the energy level scheme and doping efficiency, to determine the factors that limit the maximum achievable hole concentration in the underlying conducting layer, and to develop protocols to control the hole concentration by modifying the diamond – fluorofullerene interaction via the introduction of a porphyrin-based intralayer.

[1] P. Strobel, M. Riedel, J. Ristein, L. Ley, Nature 430, 493 (2004).

This talk is part of the Condensed Matter Physics Seminars series.

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