Effect of external magnetic field on the preparation of nitrogen-doped diamond-like carbon films

Abstract

Nitrogen-doped diamond-like carbon (DLC) films were prepared on quartz substrates and silicon wafers using the radio-frequency magnetron sputtering technique with high-purity graphite as the target material. Simultaneously, a permanent NdFeB magnet was placed on the substrate site to study the effect of an additional external magnetic field on the film growth. X-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), UV–Vis spectroscopy, and scanning electron microscopy (SEM) were used to characterize the microstructure and surface morphology of the nitrogen-doped DLC films with and without additional magnetic field. The obtained results indicate that the deposited DLC films were amorphous for both conditions. The C1s and N1s core energy levels of the XPS spectrum confirmed the formation of N=C, N≡C, and N–C bonds in the films. With an increasing nitrogen flow rate, the nitrogen content of the DLC films prepared without an additional magnetic field increased. When the nitrogen flow rate was 9 sccm, the maximum nitrogen content in the film prepared without an additional magnetic field was 24.33%. However, the maximum nitrogen content in the film prepared with an additional magnetic field increased to 32.55%, at the nitrogen flow rate of 3 sccm, and the sp3/sp2 ratio reached 1.39. The SEM results showed that the surface of the nitrogen-doped DLC film was smooth, flat, and compact after the application of the additional magnetic field, and the film was closely bonded with the substrate.