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(Negative) Electron Affinity of AlN and AlGaN Alloys

Published online by Cambridge University Press:  21 February 2011

R.J. Nemanich ,
M.C. Benjamin ,
S.P. Bozeman ,
M.D. Bremser ,
S.W. King ,
B.L. Ward ,
R.F. Davis ,
B. Chen ,
Z. Zhang  and
J. Bernholc
R.J. Nemanich
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
M.C. Benjamin
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
S.P. Bozeman
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
M.D. Bremser
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
S.W. King
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
B.L. Ward
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
R.F. Davis
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
B. Chen
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
Z. Zhang
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
J. Bernholc
Affiliation:
Department of Physics and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8202
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Abstract

The electron affinity of a semiconductor defines the relationship of the vacuum level and the semiconductor band structure. It is dependent on the atomic orbitals of the material and the surface termination. We report experimental and theoretical results that support the presence of a negative electron affinity on AlN and the Al rich AlGaN alloys. The GaN surface is found to exhibit a (positive) electron affinity of 3.3eV. The experimental measurements employ UV-photoemission spectroscopy on in situ gas-source MBE samples and on CVD samples. Theoretical results indicate that the (negative) electron affinity of AlN depends sensitively on the surface reconstruction and adatom termination. The experimental dependence of the electron affinity on alloy concentration is presented. The results indicate that AlGaN alloys with band gap similar or greater than that of diamond will exhibit a negative electron affinity. Field emission results are reported, and the characteristics are similar to those obtained from a diamond film. Issues related to cold cathode electronic devices based on NEA surfaces are noted.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 395: Symposium AAA – Gallium Nitride and Related Materials: The First International Symp , 1995 , 777
Copyright
Copyright © Materials Research Society 1996

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References

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