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Ionization Energy and Electron Affinity of Clean and Oxidized AlxGa1−xN(0001) Surfaces

Published online by Cambridge University Press:  21 March 2011

H. Nienhaus ,
M. Schneider ,
S.P. Grabowski ,
W. Mönch ,
R. Dimitrov ,
O. Ambacher  and
M. Stutzmann
H. Nienhaus
Affiliation:
Laboratorium für Festkörperphysik, Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg, Germany
M. Schneider
Affiliation:
Laboratorium für Festkörperphysik, Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg, Germany
S.P. Grabowski
Affiliation:
Laboratorium für Festkörperphysik, Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg, Germany
W. Mönch
Affiliation:
Laboratorium für Festkörperphysik, Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg, Germany
R. Dimitrov
Affiliation:
Walter-Schottky-Institut, Technische Universität München, D-85748 Garching, Germany
O. Ambacher
Affiliation:
Walter-Schottky-Institut, Technische Universität München, D-85748 Garching, Germany
M. Stutzmann
Affiliation:
Walter-Schottky-Institut, Technische Universität München, D-85748 Garching, Germany
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Abstract

Ionization energies and electron affinities of clean AlxGa1−xN(0001) surfaces were investigated by ultraviolet photoemission spectroscopy over the whole composition range. The samples were cleaned with cycles of N+-ion sputtering and annealing partly within a Ga atom flux. The ionization energy is measured as 6.5 eV and is almost independent of the aluminum content in good agreement with the general chemical trend. The electron affinity decreases linearly with composition from 3.1 eV for GaN to 0.25 eV for AlN. No evidence for negative electron affinity at AlN(0001) surfaces was found. Adsorption of oxygen at room temperature leads to a significant increase of the ionization energy and electron affinity. With AlN(0001) surfaces, an oxygen uptake of 0.6 monolayers is observed after exposures of 108 Langmuirs and the ionization energy increases by approximately 2 eV.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 680: Symposium E – Wide Bandgap Electronics , 2001 , E4.5
Copyright
Copyright © Materials Research Society 2001

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References

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