Preparation and field emission properties of Ti-CNx thin films co-deposited by pulsed cathodic arc and magnetron sputtering methods

Ti-doped CNx thin films were prepared by pulsed cathodic arc technique and magnetron sputtering with nitrogen and metallic Ti as dopants at different radio frequency (RF) powers. The microstructure, composition, and morphological features of Ti-doped CNx films were systematically investigated with respect to RF power using a suite of analytical techniques including Raman spectroscopy, x-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, UV-Vis spectrophotometry, Hall effect measurements, and field emission tests. As the sputtering power increased, the ID/IG ratio, film resistivity, relative Ti content, and Csp2 cluster concentration in the composite films exhibited an initial rise followed by a subsequent decline. Conversely, the full width at half maximum of the G peak and film roughness demonstrated an inverse trend. The nitrogen content within the films increased gradually with RF power before undergoing a subsequent decrease and subsequent resurgence. The UV average transmittance, optical bandgap, and G-peak position displayed congruent displacement trends, with Ti doping enhancing film transmittance. Furthermore, elevated Ti content contributed to an increase in the optical bandgap value. At an RF power of 350 W, the Ti-CNx composite films attained the highest Ti doping concentration, accompanied by maximal Csp2 cluster size and disorder, alongside reduced grain size and surface roughness, manifesting a dense conical surface morphology. Field emission characterization revealed that the Ti-CNx films deposited at 350 W exhibited optimal field emission performance, featuring a low turn-on electric field of 1.475 V/μm; however, their high resistivity limited the peak emission current density to 17.64 μA/cm2.