The study of bonding composition of CN_x film by thermal degradation method

Dynamic thermal degradation of amorphous carbon nitride (a-CN_x) thin films was studied in N₂ and air. The films were magnetron-sputtered at two different pressures to yield various C-C and C-N ratios. Typically, the films consist of interstitial and weakly-bonded carbon-nitrogen molecules or clusters and nitrogen-substituted graphitic-carbons. The carbon and nitrogen atoms are mainly bonded in sp, sp² and sp³ configurations that may contain N charged defects. The relative amount of nitrogen-substituted graphitic-carbons is significantly increased with plasma energy. The decomposition generally occurs in two steps. The first, initiating at ∼200 °C in air and with apparent activation energy (E_a) of ∼ 111 kJ/mol, relates to the oxidation and release of interstitial and weakly-bonded carbon-nitrogen molecules. The second, starting at ∼520 °C and having E_a of ∼140 kJ/mol, can be ascribed to the dissociation of nitrogen-substituted graphitic-carbons.