Thermal stability of tetrahedral amorphous carbon films fabricated by filtered cathodic arc technique

In order to investigate the thermal stability of the tetrahedral amorphous carbon(ta-C) films fabricated by filtered cathodic are deposition technique, ta-C films were annealed in ambient air for 3h. The annealing temperature was 200 degrees C, 400 degrees C and 500 degrees C, respectively. XPS and Raman spectroscope were employed to characterize the changes of the microstructure of the films. The results show that the XPS C1s peaks and the Raman peaks of the samples annealed at 400 degrees C or below change little. When the annealing temperature is 500 degrees C, the shape of the XPS C1s peak doesn't change too; the Raman I-D/I-G increases, the G-peak position doesn't change and the shape of Raman peak becomes more symmetry. This reveals that the sizes of the graphite clusters in the films increase and no obvious graphitization occurs during annealing process. All these indicate that the ta-C film fabricated by filtered cathodic vacuum arc technique has excellent thermal stability due to its hydrogen free and dense structure. Besides, parts of the films along the edge of the samples is evaporated by oxidation when the annealing temperature is up to 500 degrees C.