During the electron irradiation of synthetic diamond films, three successiv
e regimes are encountered as a function of the electron dose: (1) a reducti
on of the downward band bending of energy levels at the sample surface beca
use an excess of secondary electrons leaves the sample; (2) the creation of
an internal electric field in which secondary electrons drift to the surfa
ce, leading to an appreciable increase in the secondary emission and to a l
inear relation between the primary electron energy and the secondary electr
on yield; and (3) the desorption of hydrogen terminating the carbon surface
bonds. The secondary emission thus decreases to very low values. The rate
of decrease of secondary emission is similar for C:H- and C:H:Ba-terminated
diamond surfaces. (C) 1999 Elsevier Science S.A. All rights reserved.