(Negative) electron affinity of AlN and AlGaN alloys

Robert Nemanich, M. C. Benjamin, S. P. Bozeman, M. D. Bremser, S. W. King, B. L. Ward, R. F. Davis, B. Chen, Z. Zhang, J. Bernholc

Research output: Chapter in Book/Report/Conference proceedingConference contribution

37 Scopus citations


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.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium - Proceedings
PublisherMaterials Research Society
Number of pages12
StatePublished - 1996
Externally publishedYes
EventProceedings of the 1995 MRS Fall Meeting - Boston, MA, USA
Duration: Nov 26 1995Dec 1 1995


OtherProceedings of the 1995 MRS Fall Meeting
CityBoston, MA, USA

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials


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