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Z .Applied Surface Science 146 1999 287294 Imaging electron emission from diamond and IIIV nitride

Summary: Z .Applied Surface Science 146 1999 287­294
Imaging electron emission from diamond and III­V nitride
surfaces with photo-electron emission microscopy
R.J. Nemanich )
, S.L. English, J.D. Hartman, A.T. Sowers, B.L. Ward, H. Ade,
R.F. Davis
Department of Physics, North Carolina State UniÕersity, Raleigh, NC 27695-8202, USA
Department of Materials Science and Engineering, North Carolina State UniÕersity, Raleigh, NC 27695-8202, USA
Z .Wide bandgap semiconductors such as diamond and the III­V nitrides GaN, AlN, and AlGaN alloys exhibit small or
even negative electron affinities. Results have shown that different surface treatments will modify the electron affinity of
Z .diamond to cause a positive or negative electron affinity NEA . This study describes the characterization of these surfaces
Z .with photo-electron emission microscopy PEEM . The PEEM technique is unique in that it combines aspects of UV
photoemission and field emission. In this study, PEEM images are obtained with either a traditional Hg lamp or with tunable
UV excitation from a free electron laser. The UV-free electron laser at Duke University provides tunable emission from 3.5
Z .to greater than 7 eV. PEEM images of boron or nitrogen N -doped diamond are similar to SEM of the same surface
indicating relatively uniform emission. For the N-doped samples, PEEM images were obtained for different photon energies
ranging from 5.0 to 6.0 eV. In these experiments, the hydrogen terminated surface showed more intense PEEM images at
lower photon energy indicating a lower photothreshold than annealed surfaces which are presumed to be adsorbate free. For
the nitrides, the emission properties of an array of GaN emitter structures is imaged. Emission is observed from the peaks,


Source: Ade, Harald W.- Department of Physics, North Carolina State University


Collections: Physics