Study of carbon nitride compounds synthesised by co-implantation of ¹³C and ¹⁴N in copper at different temperatures

Carbon nitride compouns have been synthesised in copper by simultatneous high fluence (10¹⁸ at/cm²) implantation of ¹³C and ¹⁴N ions. During the implantation process, the substrate temperature was maintained at 25, 250, 350 or 450°C. Depth profiles of ¹³C and ¹⁴N were determined using hte non-resonant nuclear reactions (NRA) induced by a 1.05 MeV deuteron beam. The retained doses were deduced from NRA measurements and compared to the implanted fluence. The chemical bonds between the carbon and nitrogen were studied as a function of depth and temperature by X-ray photoelectron spectroscopy (XPS). The curve fitting of C1s and N1s core level photoelectron spectra reveal different types of C-N bonds and show the signature of N2 molecules. The presence of nitrogen gas bubbles in copper was highlighted by mass spectroscopy. The structure of carbon nitride compounds was characterised by transmission electron microscopy (TEM). For that purpose, corss-sectional samples were prepared using a focused ion beam (FIB) systeme. TEM observations showed the presence of small amorphous carbon nitride "nano-capsules" and large gas bubbles in copper. Based on our observations, we propose a model for the growth of these nano-objects. Finall, the mechanical properties of the implanted samples were investigated by nano-indentation.