| By adjusting a series of experimental parameters, such as working pressure, substrate temperature, sputtering power, and CH4/N2/Ar flow ratio, amorphous B-C-N films with various compositions were synthesized on silicon (100) substrate via radio frequency magnetron sputtering. The structure, chemical compositions, and hardness of B-C-N films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nanoindentation techniques. The main work is given below:(1) FTIR spectra and XRD patterns reveal that all these synthesized B-C-N films are atomic-level hybrids composed of B, C and N atoms. Among them, various chemical bonds can be enhanced by increasing the substrate temperature, increasing the sputtering power of single graphite target, or increasing the sputtering power of boron and graphite targets simultaneously in a lower range; the C=C bond can be strengthened by increasing the working pressure, or introducing the CH4 gas into the mixture of N2/Ar; however, high sputtering power of boron target is detrimental to the formation of chemical bonds in B-C-N films. Therefore, the chemical bonds states can be tuned by varying different experimental parameters.(2) On the B-C-N ternary phase diagram, the chemical compositions of most synthesized films distribute along the C-BN isoelectronic line. Among them, the low-carbon compositions can be obtained by decreasing the N2/Ar flow ratio, increasing the power of boron and graphite targets simultaneously, or increasing the substrate temperature; those carbon-rich ones can be prepared by introducing the CH4 gas into the mixture of N2/Ar reactive gas. Therefore, it is possible to control the compositions of B-C-N films by adjusting a set of experimental parameters.(3) Hardness of these synthesized B-C-N films is hardly dependent on the substrate pretreatment, but determined by the bond type as the result of FTIR analysis.
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