UV photoemission study of heteroepitaxial AlGaN films grown on 6H-SiC

M. C. Benjamin, M. D. Bremser, T. W. Weeks, S. W. King, R. F. Davis, R. J. Nemanich

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Abstract

This study presents results of UV photoemission measurements of the surface and interface properties of heteroepitaxial AlGaN on 6H-SiC. Previous results have demonstrated a negative electron affinity of AlN on 6H-SiC. In this study Al x Ga 1-x N alloy films were grown by organometallic vapor phase epitaxy (OMVPE) and doped with silicon. The analytical techniques included UPS, Auger electron spectroscopy, and LEED. All analysis took place in an integrated UHV transfer system which included the analysis techniques, a surface processing chamber and a gas source MBE. The OMVPE alloy samples were transported in air to the surface characterization system while the AlN and GaN investigations were prepared in situ. The surface electronic states were characterized by surface normal UV photoemission to determine whether the electron affinity was positive or negative. Two aspects of the photoemission distinguish a surface that exhibits a NEA: (1) the spectrum exhibits a sharp peak in the low kinetic energy region, and (2) the width of the spectrum is hv - E g . The in situ prepared AlN samples exhibited the characteristics of a NEA while the GaN and Al 0.13 Ga 0.87 N samples did not. The Al 0.55 Ga 0.45 N sample shows a low positive electron affinity. Annealing of the sample to > 400°C resulted in the disappearance of the sharp emission features, and this effect was related to contaminant effects on the surface. The results suggest the potential of nitride based cold cathode electron emitters.

Original languageEnglish (US)
Pages (from-to)455-460
Number of pages6
JournalApplied Surface Science
Volume104-105
DOIs
StatePublished - Sep 1996
Externally publishedYes

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ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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