Angular-resolved study of secondary-electron emission from NEA diamond surfaces

We studied the angular distribution of secondary electrons emitted from dif ferent diamond surfaces using angular-resolved ultraviolet photoelectron sp ectroscopy (ARUPS). On a boron-doped IIb type natural diamond, smooth and c lean(lll) surfaces were prepared by polishing and vacuum annealing. A negat ive electron affinity (NEA) was established by applying cesium at different coverages. The intensity of the secondary-electron emission, which origina tes from thermalized electrons collected in the conduction-band minimum, as well as the low-energy cutoff of the spectra were studied for different em ission angles with respect to the sample surface and for different cesium c overages. While the intensity is peaked in the direction normal to the samp le surface, we observed an upward dispersion of the low-energy cutoff of th e spectra for off-normal detection angles. A theoretical model for this beh avior is given. The same effects are evident to a lower extent for a polycr ystalline, boron-doped, chemical vapor deposited (CVD) diamond film. (C) 19 99 Elsevier Science S.A. All rights reserved.