Charge transfer doping of silicon.
We demonstrate a novel doping mechanism of silicon, namely n-type transfer doping by adsorbed organic cobaltocene (CoCp2*) molecules. The amount of transferred charge as a function of coverage is monitored by following the ensuing band bending via surface sensitive core-level photoelectron spectroscopy. The concomitant loss of electrons in the CoCp2* adlayer is quantified by the relative intensities of chemically shifted Co2p components in core-level photoelectron spectroscopy which correspond to charged and neutral molecules. Using a previously developed model for transfer doping, the evolution in relative intensities of the two components as a function of coverage has been reproduced successfully. A single, molecule-specific parameter, the negative donor energy of -(0.50±0.15)  eV suffices to describe the self-limiting doping process with a maximum areal density of transferred electrons of 2×1013  cm-2 in agreement with the measured downward band bending. The advantage of this doping mechanism over conventional doping for nanostructures is addressed.
Department of Physics, La Trobe University, Victoria 3086, Australia.
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KJ
Rietwyk
Department of Physics, La Trobe University, Victoria 3086, Australia.
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Y
Smets
Max-Planck-Institute for the Science of Light, D-91058 Erlangen, Germany and Institute of Nanoarchitectures for solar energy conversion, Helmholtz-Centre Berlin (HZB), D-14109 Berlin, Germany.
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M
Bashouti
Institute of Nanoarchitectures for solar energy conversion, Helmholtz-Centre Berlin (HZB), D-14109 Berlin, Germany.
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SH
Christiansen
Department of Physics, La Trobe University, Victoria 3086, Australia.
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A
Schenk
Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia.
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A
Tadich
School of Physics, Monash University, Clayton, Victoria 3800, Australia.
M T
MT
Edmonds
Technische Physik, Universität Erlangen, D-91058 Erlangen, Germany.
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J
Ristein
Department of Physics, La Trobe University, Victoria 3086, Australia and Technische Physik, Universität Erlangen, D-91058 Erlangen, Germany.
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L
Ley
Department of Physics, La Trobe University, Victoria 3086, Australia.
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Pakes