Effect of discharge pulse frequency on the microstructure and field-emission performance of CNX films deposited by pulse cathode arc evaporation

CNX thin films were prepared by a pulse cathode arc technique using nitrogen as a dopant at different frequencies. Microstructure, compositions, and morphology of CNX thin films were investigated in the dependence of discharge pulse frequency by Raman spectroscopy, x-ray photoelectric spectroscopy (XPS), atomic force microscopy, scanning electron microscopy, UV–vis spectrophotometry, Hall measurements, and field-emission test. The results of Raman and XPS showed that the Csp2 cluster size of CNX films decreases and then increases and decreases with discharge pulse frequency increasing. The Csp2 cluster size of the films prepared at 9 Hz was the largest. The size of Csp3 content increases for the CNX films at the high discharge pulse frequency. The variation of C–N bonding content with frequency in CNX films is similar to that of Csp2. CNX thin films prepared at a frequency of 9 Hz were improved field-emission properties corresponding to the variation of microstructure parameters (the size and ordering of Csp2 clusters) and compositions (C–N bonds). The excellent field-emission properties, such as a low turn-on electric field of 2.1 V/μm and a high field-emission current density of 517.34 μA/cm2, were obtained.