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Barrier Height Reduction at the Pd-Ge/n-GaAs Interface

Published online by Cambridge University Press:  26 February 2011

P. L. Meissner ,
J. C. Bravman ,
T. Kendelewicz ,
C. J. Spindt ,
A. Herrera-Gómez ,
W. E. Spicer  and
A. J. Arko
P. L. Meissner*
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305
J. C. Bravman
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305
T. Kendelewicz
Affiliation:
Stanford Electronics Laboratory, Stanford University, Stanford, CA 94305
C. J. Spindt
Affiliation:
Stanford Electronics Laboratory, Stanford University, Stanford, CA 94305
A. Herrera-Gómez
Affiliation:
Stanford Electronics Laboratory, Stanford University, Stanford, CA 94305
W. E. Spicer*
Affiliation:
Stanford Electronics Laboratory, Stanford University, Stanford, CA 94305
A. J. Arko
Affiliation:
Los Alamos National Laboratory, Los Alamos, NM
*
† Current address: Spectrum Analysis, Inc. 41626 Mahoney St., Fremont, CA 94538
‡ Stanford Asherman Professor of Engineering.
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Abstract

We present the first direct measurements showing changes in the Schottky barrier height for ohmic Pd-Ge contacts to n-type GaAs. The barrier height and interface chemistry were investigated with high resolution synchrotron ultraviolet photoemission spectroscopy. Interfaces were formed by the deposition of one layer each of Pd and Ge on the GaAs substrate, where the deposition sequence was varied to allow a more quantitative determination of the role of each element. A reduction of 0.35 eV in the barrier height occurred in the case where Pd was deposited first. This reduction can be described by a model in which interface states are compensated by charge from As n-type doping of the Ge layer in the Ge-GaAs heterojunction. The dramatic change in barrier height seen when Pd is deposited first contrasts sharply with the stable barrier height observed for the case where the Ge was deposited first, a constant barrier of 0.75 eV was found after every deposition and annealing step. This stability was correlated with constant Ga and As concentrations in the Ge and a relatively low overall As concentration in the overlayer.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 240: Symposium E – Advanced III-V Compound Semiconductor Growth, Processing and Devices , 1991 , 485
Copyright
Copyright © Materials Research Society 1992

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References

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