The work function of the Cu-deposited Ti emitter

We have measured the field-emission characteristics of the Cu-deposited Ti emitter and studied the change in the work function due to the Cu deposition. The emitter work function was obtained from the slope of the Fowler-Nordheim plot. Upon depositing Cu on Ti, we found that the work function increases by 0.1-0.2 eV. Annealing the deposited emitter gives a larger increase in the work function. We could not observe the reduction in work function predicted by Yoshitake and Yoshihara [J. Vac. Sci. Technol. A13 (1995) 2407] for the Cu-segregated Ti emitter. This discrepancy indicates the importance of the structural difference between the segregated and metal-deposited surfaces, which has not been considered in the study of the change in the work function due to surface segregation. (C) 1998 Elsevier Science B.V. All rights reserved.