Superhard amorphous carbon films fabricated by PLD

Pulsed laser deposition(PLD) was used to prepare superhard amorphous carbon films. The films’ surface appearance, structure, residual stress, hardness and XPS spectra were researched. AFM and SEM images show the film fabricated by PLD is flat, smooth and compact with the root mean square roughness less than 1nm (the maximum is 0.877 nm). Large residual stress of the films was measured by XRD, which would cause corrugation and break in the films prepared under high laser repetition frequency and fluence. However, the stress would relax under 300 ℃ annealing temperature. Nanoindentation test shows that hardness and Young’s modulus of film were over 20 GPa and 200 GPa respectively. XPS tells that the content of sp3 was between 39% and 53%, which was in direct proportion to laser fluence.