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. W e report here on the field emission performance of Mo tip emitters coa ted 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 whi ch showed a continuous variation in column angle, size and density fro m the shrank to the apex, similar to those observed from the amorphous diamond films. Field emission measurements from Mo tip emitters coate d 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 betwee n the Mo and the a-D:N films. (C) 1997 Elsevier Science S.A.