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Simulations of the electrostatic potential in a thin silicon specimen containing a p-n junction

Published online by Cambridge University Press:  01 February 2011

P.K. Somodi ,
R.E. Dunin-Borkowski ,
A.C. Twitchett ,
C.H.W. Barnes  and
P.A. Midgley
P.K. Somodi
Affiliation:
Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.
R.E. Dunin-Borkowski
Affiliation:
Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.
A.C. Twitchett
Affiliation:
Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.
C.H.W. Barnes
Affiliation:
Department of Physics, University of Cambridge, Madingley Road, Cambridge CB3 0HE, U.K.
P.A. Midgley
Affiliation:
Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.
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Abstract

The measurement of potentials associated with dopant atoms in semiconductors at nanometer spatial resolution using off-axis electron holography is known to be affected by the presence of the surfaces of thin specimens. In particular, the potential across a p-n junction is often found to be lower than would be expected from predicted properties of bulk devices. Here we present simulations of two-dimensional potential profiles within a thin (<1 µm) parallel-sided specimen containing a p-n junction. We find that the potential across the p-n junction is always smaller, when projected through the specimen, than would be expected from the properties of the bulk material. Crucially, the step in potential across the junction is independent of the value of the potential on the surface of the specimen for high dopant concentrations (>1017 cm−3). The simulations are compared with experimental data. Although they can account for some of the reduction in the observed potential, they do not fully explain the experimental results.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 839: Symposium P – Electron Microscopy of Molecular and Atom-Scale Mechanical Behavior, Chemistry, and Structure , 2004 , P3.2
Copyright
Copyright © Materials Research Society 2004

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References

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