Electron emission properties of crystalline diamond and III-nitride surfaces

Contributors:   Robert J. Nemanich, P.K. Baumann, M.C. Benjamin, O.-H. Nam, A.T. Sowers, B.L. Ward, H. Ade, and R.F. Davis

ABSTRACT

Wide bandgap semiconductors have the possibility of exhibiting a negative electron affinity (NEA) meaning that electrons in the conduction band are not bound by the surface. The surface conditions are shown to be of critical importance in obtaining a negative electron affinity. UV-photoelectron spectroscopy can be used to distinguish and explore the effect. Surface terminations of molecular adsorbates and metals are shown to induce an NEA on diamond. Furthermore, a NEA has been established for epitaxial AlN and AlGaN on 6H-SiC. Field emission measurements from flat surfaces of p-type diamond and AlN are similar, but it is shown that the mechanisms may be quite different. The measurements support the recent suggestions that field emission from p-type diamond originates from the valence band while for AlN on SiC, the field emission results indicate emission from the AlN conduction band. We also report PEEM (photo-electron emission microscopy) and FEEM (field electron emission microscopy) images of an array of nitride emitters.

Publisher: Applied Surface Science,   Volume: 130-132,   694-703 ||  Published: 1997-10 ||   PDF (400.64 KB) ||   Read more...