Elucidation of field emission characteristics of phosphorous-doped diamond films

Field emission characteristics are investigated using phosphorous (P)-doped polycrystalline and homoepitaxial diamond films. A significant variation in turn-on voltage is observed for different cathode metals on the polycrystalline and homoepitaxial diamond films. This experimental-fact shows that the internal electron emission at the diamond/cathode contact dominates the field emission characteristics. We also investigate the temperature dependence of the field emission characteristics for P-doped polycrystalline diamond films in comparison with those of the undoped one. The turn-on voltage decreases with increasing temperature for the P-doped diamond film. On the other hand, no variation in the turn-on voltage occurs for the undoped diamond film. This behavior of the field emission characteristics is well explained by the thermionic field emission theory combined with the temperature dependence of the ionized donor concentration. (C) 1999 American Vacuum Society. [S0734-211X(99)11802-X].