Secondary electron emission measurements on synthetic diamond films

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.