Electron emission properties of diamond and III-V nitrides

摘要

Wide bandgap semiconductors such as diamond and the III-V nitrides of GaN and AlN exhibit small or even negative electron affinities. Recent results have shown that surface treatments will modify the electron affinity of diamond to cause a negative electron affinity (NEA). Results are presented which correlate the field emission fromsingle crystal p-type (boron doped) diamond with the electron affinity of the surfaces. The field emission is explored for nitrogen doped polycrystalline films. The threshold for field emission is significantly higher than from p-type diamond, and in fact, most surfaces are severely damaged during the emission measurement. High resolution photo-electron emissionmicroscopy (PEEM) and field emission electron microscopy (FEEM) are employed to determine the relation of the emission to the surface morphology. PEEM results presented for diamond indicate relatively uniform emission with increased intensity at proturding crystallite edges. Results are presented for cold cathodes fabricated from epitaxial nitrides grown on 6H-SiC.