Modification on the electron field emission properties of diamond films: The effect of bias voltage applied in situ

In this work, we have systematically examined the effect of bias voltage applied in situ on the characteristics of diamond films. Raman spectroscopic and scanning electron microscopic examinations indicate that the applied positive bias voltage changes the thin films' morphology and the Raman spectroscopy insignificantly, but markedly lowers their effective work function (Phi(e)) and turn-on field (E-0). The enhancement of the field emission properties of these films is assumed to result from the introduction of impurity and surface states. By contrast, the negative bias voltage applied during a chemical vapor deposition process leads to pronounced modification of the morphology of diamond films due to an etching effect. Such a process results in a fine granular structure for the diamond films, significantly improving their field emission behavior via the enhancement of field concentration effect. (C) 1998 American Institute of Physics. [S0021-8979(98)07019-4].