Nanoindentation study on nitrogenated tetrahedral amorphous carbon thin films with ultra low load

Abstract

This paper reports the improved nanomechanical properties of as grown and nitrogen incorporated tetrahedral amorphous carbon (ta-C, ta-C: N) films deposited by S-bend filtered cathodic vacuum arc (FCVA) technique using nanoindentation. The effect of varying amount of nitrogen incorporation on the nanomechanical properties of ta-C films deposited at a high substrate bias of -300 V at ultra low load of 1.4 mN has been studied. It has been found that the nitrogenation has improved the mechanical properties of ta-C films. The hardness H of 27.8 GPa with improvement of ~30 % and plastic index parameter (ratio of H to elastic modulus E) (H/E) of 0.091 with improvement of ~ 25 % has been obtained for ta-C: N films deposited at a nitrogen partial pressure of 1.9 10^-2 Pa. Improved H and H/E of ta-C: N films may be due to the better ionization and incorporation of nitrogen in a carbon matrix at the high negative substrate bias used in the deposition of FCVA technique.