Electron field emission from Ti-containing tetrahedral amorphous carbon films deposited by filtered cathodic vacuum arc

Titanium-containing tetrahedral amorphous carbon (ta-C:Ti) films with diffe rent titanium content were deposited by a filtered cathodic vacuum are tech nique. The microstructure of these films was confirmed to be of ta-C+TiCx(x <1) nanocomposite by Rutherford backscattering spectroscopy, x-ray diffract ion, and micro-Raman spectroscopy experiments. With the increase of titaniu m content, the titanium carbide content increased and the sp(3) fraction in the residual ta-C phase decreased gradually. In the electron field emissio n tests, it was found that proper conditioning processes are necessary for all these films in order to get a steady reproducible emission behavior. Af ter conditioning, the emission threshold field of the films is about the sa me value, around 10 V/<mu>m, except for the film with the lowest titanium c ontent (similar to1.2 at%) of which the threshold field is much higher, aro und 17-18 V/mum. The optimum titanium concentration in the film for field e mission, showing the highest emission current and emission site density, is about 12 at%. After field emission testing, graphitization was involved an d the titanium carbide phase, at least some of the sub-stoichiometric TiCx phase, in the ta-C:Ti films decomposed. (C) 2000 American Institute of Phys ics. [S0021-8479(00)04224-9].