Characterization of magnetron sputter CNx thin films

Carbon nitride thin films were deposited at different substrate temperature (ST) by using reactive magnetron sputtering in a pure N-2 discharge, and studied by laser Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometer. The Raman spectra of the films show that I(D)/I(G) decreased with the increase of ST. The D bandposition shifted towards lower frequency, while the G bandposition shifted towards higher frequency as the ST increased. The XPS data exhibit that N1s binding states also depend on ST. The optical band gap of the films is found dropped from 0.22 eV to 0.10 eV with the increase of ST.