Effect of Substrate Temperature on Carbon Nitride Thin Films Prepared by Radio Frequency Sputtering

Carbon nitride thin films have been deposited by radio frequency sputtering at different substrate temperatures. The electronic structure and optical properties of the films have been systematically studied for the different substrate temperatures. The maximum N concentration in the films arrived at 41 at.%. The binding energy of core levels C 1s and N 1s produces a large shift in the range of 3.5-0.3eV depending on substrate temperature T_s. The band gap is at about 0.61-1.22eV. N atom concentration and shift of core level as well as electron band gap decrease with increasing T_s, which illustrates that raising T_s is not a good way to form carbon nitride films. Ultraviolet-visible near infrared spectra show that the films have a good transparency in near infrared region, but there is a sharp absorption peak around 2720 nm. The peak disappears when T_s is higher than 400°C.