Field emission enhancement from Mo tip emitters coated with N containing amorphous diamond films

Previous studies have shown that amorphous diamond (a-D) films can be deposited on sharp Mo tip emitters at room temperature by pulsed laser deposition, to achieve a substantial improvement in field emission. We report here on the field emission performance of Mo tip emitters coated with nitrogen containing amorphous diamond (a-D:N) films by pulsed laser deposition. The a-D:N film was prepared in an N-2 pressure of 3.7 x 10(-1) Pa with a laser fluence of 25 J/cm(2). High resolution TEM images revealed that the films had a nano-columnar microstructure which showed a continuous variation in column angle, size and density from the shrank to the apex, similar to those observed from the amorphous diamond films. Field emission measurements from Mo tip emitters coated with the a-D:N film indicated a further considerable improvement in turn-on voltage and emission current as compared with those of the a-D film coated Mo emitters. Such an enhancement in field emission may be ascribed to a shallow N donor level in amorphous diamond resulting in the formation of a narrower potential barrier at the interface between the Mo and the a-D:N films. (C) 1997 Elsevier Science S.A.