Preparation of fluorinated amorphous carbon nitride films by magnetron sputtering

Abstract

Fluorinated amorphous carbon nitride (a-C_1-x N_x : F) films were prepared by magnetron sputtering to reduce the C≡N bonding configuration and the dangling bond density, while increasing the optical bandgap over that of amorphous carbon nitride (a-C_1-x N_x) and hydrogenated amorphous carbon nitride (a-C_1-x N_x : H) films. The structural, optical, and defect properties of these films were investigated by infrared absorption, X-ray photoelectron spectroscopy, ultraviolet–visual spectroscopy, and electron spin resonance (ESR) measurements. No IR peaks due to C≡N bonding were observed for the a-C_1-x N_x : F films, indicating that the amount of C≡N bonding decreased with the incorporation of fluorine atoms. Furthermore, IR signals due to the Raman G band were not observed in any of the films, although the Raman D band was observed for all of them. In addition, the IR spectra revealed that CF2 bonding dominated over CF bonding. These results can be explained in terms of a decrease in structural dimension owing to fluorine incorporation and a ‘perfect’ amorphous structure that has no graphite crystalline region. The dangling bond density, peak to peak line width, g values of the ESR spectra, and optical bandgap for a-C_1-x N_x : F films were smaller than those for a-C : F films.