Field emission characteristic of diamond films grown by electron assisted chemical vapor deposition

By introducing positive substrate bias, ranging from 0 to 200 V, to the sub strate during the growing procedure of diamond at 1, 2, and 3% CH4 concentr ation, we have investigated the effect of electron bombardment on modificat ion of the structural property and the surface morphology of diamond films, and consequently the field emission properties. When increasing the bias v oltage for each CH4 concentration, the structural properties of diamond fil ms are significantly deteriorated together while the non-diamond carbon com ponent increased and the surface morphologies of the films lost their uniqu e facet shape. The reason for the deterioration of the structural property was attributed to both the increase of substrate temperature and the excess ive generation of CHn radicals. Especially for the films deposited at 2% CH 4 concentration under 100 V, it was observed that their morphological and s tructural characteristics approached those of graphitic carbon nature. The field emission properties of diamond films were substantially improved with increasing the CH4 concentration and with the application of bias voltage for each CH4 concentration. In order to investigate the correlation between the enhancement of field emission properties and the emission sites, we ha ve examined the spatial distribution of the emission sites. From this resul t, a possible emission mechanism is discussed. (C) 1999 Elsevier Science S. A. All rights reserved.