Photoelectron emission from the negative electron affinity caesiated natural diamond (100) surface

The unique property of negative electron affinity (NEA) makes diamond surfaces very interesting for technical applications like cold cathodes and field emitters. We investigated the hydrogen-terminated and hydrogen-free, caesiated diamond (100) surfaces by means of low-energy electron diffraction, X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. The photoemission measurements permit us to determine the electron affinity and to draw the band diagrams for these differently terminated surfaces. The NEA peak reappears after caesiation of the hydrogen-free surface, whereas it vanishes after exposure to molecular oxygen. From the shift of the C 1s core level, an increasing downward band-bending of 1.2 eV was inferred following caesiation of the hydrogen-free surface and 0.6 eV following caesiation of the hydrogen-terminated surface. (C) 1998 Elsevier Science S.A.